(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Biodiversity Heritage Library | Children's Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Climatic cycles and tree-growth"

BINDING UST m , m 



CARNEGIE INSTITUTION OF WASHINGTON 
Publication No. 289, Vol. II 




1928 



/ 



CLIMATIC CYCLES AND TREE-GROWTH 

VOLUME II 

A STUDY OF THE ANNUAL RINGS OF TREES IN 
RELATION TO CLIMATE AND SOLAR ACTIVITY 



BY 



A. E. DOUGLASS 

Director of Steward Observatory, University of Arizona 






Published by the Carnegie Institution of Washington 
Washington, 1928 



i 



7vr 

i/. L 



J. B. LIPPINCOTT COMPANY 

EAST WASHINGTON SQUARE 

PHILADELPHIA, PENNA. 



CONTENTS 



PAGE 

I. Introduction 3 

Affiliations 3 

Development 4 

Cooperation 5 

Acknowledgments 6 

Previous work 7 

II. Tree selection 8 

Species 8 

Location: grouping, soil, topography, 

altitude 12 

Condition: injuries, fire scars 14 

Collection purposes: cycles and secu- 
lar changes, age estimates 15 

III. Radials 17 

Selection 17 

Living trees: place and direction of 

boring 17 

Fallen trees 19 

Stumps: v-cut and its location 19 

Preparing the radial 21 

Radial studies 22 

Circuit uniformity: eccentricity, 

lobes and gross rings 22 

Vertical uniformity: tests at 

different heights 24 

IV. Rings 28 

Selection in group 28 

Mean conformity 28 

Mean sensitivity 29 

Selection within record 30 

Parts of tree's record: infancy, 

youth, maturity, age 30 

Ring errors : superfluous, missing, 

reinforced, and false rings 31 

V. Instruments and technique 34 

Collecting tools : saws, borers, paraffin 

treatment 34 

Measuring instruments 37 

Early forms 37 

Plotting micrometer; auto-plot . . 37 

Longitudinal plotter; long-plot. . 39 

Clerical operations 40 

Standardizing 40 

Cycle plots: skeleton plots, 

smoothing, Hanning 42 

The cyclograph (periodograph) 45 

Comparison of analyzing methods 45 

Principle of the cyclograph 46 

The White cyclograph 47 

Cycloscope 50 

VI. Tree records: length 51 

Old sequoia records 51 

Third sequoia trip, 1919 51 

Fourth sequoia trip, 1924 52 

Fifth sequoia trip, 1925 54 

Coast redwood records 55 

Santa Cruz group, 1921 55 

Scotia trip, 1925 55 

Deficiency of the coast redwood 56 



PAGE 

VI. Tree records: length — continued 

Old pine records 57 

Search for old trees; 500- and 

640-year pines, burnt centers . 57 

Prehistoric material 59 

California and Arizona cross- 
dating 61 

Charleston Mountain trip 61 

VII. Tree records: geographical dis- 

tribution 63 

Western circuit, 1925 63 

Western contours and rainfall ... 64 

The three zones 64 

The Pueblo area 65 

Southwestern contours 66 

Western pine groups: statistics and 

treatment 67 

Arizona region 68 

First Flagstaff group 68 

Flagstaff 500-year group 69 

Fort Valley group 69 

High-level group 71 

Flagstaff shadow group 71 

Flagstaff northeast group 72 

Grand Canyon group 72 

Dixie Forest (Utah) group 73 

Upper Rim group 73 

Lower Rim group 74 

Cibecue group 74 

Pinal Mountain group 75 

Catalina Mountain group 75 

Santa Rita group 76 

The Rocky Mountain zone 77 

Yellowstone group 77 

Laramie, Wyoming, group 77 

Clements's Pike's Peak group . . 77 

Pike's Peak Timberline group . . 79 

Pike's Peak Basin group 79 

Upper North Transect group ... 79 

Lower North Transect group ... 80 

South Transect group 80 

Brook group of Douglas fir ... . 80 
Brook group of Engelmann 

Spruce 81 

Cloudcroft, New Mexico, group. 81 

Santa Fe group 82 

Basin Mountain Upper group ... 82 

Basin Mountain Lower group ... 83 

Aztec East group 83 

The Coast zone 83 

Boise, Idaho, group 83 

Baker, Oregon, group 85 

Dalles group 85 

Oregon Coast group 85 

Klamath Falls group 86 

Plumas County group 86 

Calaveras group of pines 87 

Big Creek group 87 

Springville group of pines 88 

Mount Wilson group 88 



VI 



CONTENTS 



PAGE 

VII. Tree records: geographical dis- 

tribution. The Coast zone — 

continued 

San Bernardino group 89 

Charleston Mountain group .... 89 

Pine Valley group 90 

Miscellaneous groups 90 

Sequoias 90 

Coast redwoods 91 

Arizona groups 91 

Other western groups 91 

North American groups 92 

Foreign groups 93 

VIII. Environment 94 

Effects in trees 94 

Climate : single and double rings . 94 

Rainfall correlations: Prescott, 
Flagstaff, Cibecue drought 

record; sequoia 97 

Conservation: reversed and dis- 
torted effects 10° 

Other climatic correlations; wind 102 

Topography 102 

Sequoia topography: ring type 
and moisture, sensitivity and 

cycle lag 103 

Pike's Peak topography; kind 

of tree I 06 

San Francisco Peaks; altitude, 

shadow effect, and soil 107 

Changing conditions : shade, drain- 
age, soil, and grouping 110 

Environment indicators Ill 

Evidence in individual rings .... Ill 



PAGE 

VIII. Environment. Environment indi- 

cators — continued 

Evidence in single trees Ill 

Changing ring-size 112 

IX. Cycles H3 

Cycle origins 1 13 

Solar theory: sunspots, rotation, 

radiation 113 

Terrestrial reaction: tempera- 
tures, droughts, electrostatics, 
glacial varves, ocean rotation, 

etc H5 

Cycles in tree-growth 117 

Cycle reliability: short and long 

cycles, criteria and tests 117 

The periodocrite 1 19 

Zone centers and their mean 

curves 120 

Meteorological areas; the prob- 
lem of combination 122 

Cycles in western zones: arcigram, 
zone summaries, sequoia cycles 123 
Solar records in tree-growth ; histori- 
cal confirmation, dearth cycles, 
wet and dry climatic effects. . . . 125 
Solar cycles, historical changes, cli- 
matic patterns 127 

Cyclograms 130 

Cycles and climate; cautions; possible 

future Flagstaff variations 133 

Summary 136 

Appendix 139 

Tables or group averages, standard- 
ized 139 

Bibliography 159 



ILLUSTRATIONS 



PLATES 



PAGE 

Plate 1. 

A. Fire injury on D-12 (stump) showing 

repair and gross rings and in- 
closed bark 14 

B. Center of oldest sequoia, D-21, show- 

ing ring grown in 1305 B.C.; three 
pins stand at 1300 b.c 14 

Plate 2. 

A. Weathering in 60 years, CV-4; bark 

gone, sap wood mostly gone; Cala- 
veras Grove 20 

B. Weathering in 125 years; CV-3, 

sapwood and center entirely 

gone ; Calaveras Grove 20 

Plate 3. 

A. Forms of v-cut on stumps 22 

B. Complacent sequoia rings, D-8, 

grown in wet basin 22 

C. Sensitive sequoia rings, D-4, grown 

in uplands 22 

D. Hyper-sensitive or erratic yellow 

pine rings, Pr. 62, grown near 
lowest yellow pine levels, Arizona 22 
Plate 4. 

A. Fallen sequoia, Enterprise, in which 
vertical uniformity tests were 
made 26 



Plate 4 — continued. 

PAGE 

B. Sequoia "California," Enterprise; 

and Mr. C. A. Elster 26 

Plate 5. 

A. Plotting micrometer 38 

B. Longitudinal plotter 38 

C. White cyclograph 38 

Plate 6. 

A. Site of 500-year pines, Flagstaff, 

Fl. 35, in foreground; looking 
south 58 

B. Stump of 640-year pine, Fisher's 

Tank, Flagstaff 58 

Plate 7. 

A. Sequoia topography, ridges; area of 

D-l, 2, 3, 4, 5, 18, 19, 28, 29 
and 30 104 

B. Sequoia topography, basins; area of 

D-6, 7, 8, 9, 10, 11 and 27 104 

Plate 8. 

Spruce, S-14, from South Sweden, show- 
ing sunspot cycle; wet climate 
reaction. Dots give dates of sun- 
spot maxima beginning with 1830 126 
Plate 9. 

Cyclograms 132 



TEXT-FIGURES 



PAGE 

1. Heartwood rings at different heights in 
the sequoia 25 

2. Sapwood rings in fallen sequoia 26 

3. Mean sensitivity and soil moisture .... 29 

4. Arizona zone, smoothed group curves. . 70 

5. Rocky Mountain zone, smoothed 
group curves 78 

6. Coast zone, smoothed group curves ... 84 

7. Prescott rainfall and tree-growth 98 

8. Flagstaff rainfall and tree-growth, 
with comparison curves; tree-growth 
shows close relation to winter pre- 
cipitation 99 

9. Cibecue drought record traced directly 
from autoplot 100 

10. Sequoia growth and rainfall 100 

11. Land contours and annual growth of 
sequoias in Redwood Basin 104 



PAGE 

12. Ring-size, sensitivity, and rainfall 
correlations, Prescott 105 

13. Pike's Peak area mean curve, PPM; 
average of six groups, standardized 
and smoothed 121 

14. Sierra Nevada area mean curve, SNM ; 
average of four groups, standardized 
and smoothed 121 

15. Cycles in western zones 124 

16. Sequoia cycles 125 

17. Flagstaff century curve, FLC, a.d. 
1285-1700 ; standardized and smoothed 127 

18. (1) Flagstaff area mean curve, FAM; 
average of eight groups, standardized 
and smoothed; (2) synthetic curve; 

(3) residuals 128 

19. Details of cyclogram patterns in 
Plate 9 132 



CLIMATIC CYCLES AND TREE-GROWTH 

VOLUME II 

A STUDY OF THE ANNUAL RINGS OF TREES IN 
RELATION TO CLIMATE AND SOLAR ACTIVITY 

By A. E. Douglass 

Director of Steward Observatory, University of Arizona 

With nine plates and nineteen text figures 



CLIMATIC CYCLES AND TREE-GROWTH 

VOLUME II 



I. INTRODUCTION 

In a dry region the dominating physical factor in tree-growth is 
moisture. It is impossible for anyone to realize how vital it is 
without actual residence — a mere trip through a desert is far from 
sufficient, for it lacks the time element. One must live in it by night 
and by day, in rainy and in dry season, in drought and in wet cycle. 
One must see the burning sun, the sparse shrubs, the clear skies, the 
striking colors of earth, rock, and sky, without the green of vegetation, 
followed by the strong primitive atmospheric colors when the sun is 
just below the horizon; he must see the round green cedars and the 
ever watchful isolated pines of higher elevations; he must see green 
valley bottoms and herds escaping from sight through deep range 
grass at one time, and later on he must travel through cactus wastes 
and dead cattle lying beside dried-up water-holes. And all this must 
be lived with to afford full realization. The visitor from wet climates 
does not sense it all for the first year or two, for day by day he 
unconsciously expects a change, as has always happened in his pre- 
vious experience. But after a year or more he is able to realize the 
excessive value of moisture and even to recognize the evidence of 
climatic changes. 

This was the approach in the present study of climate and trees. 
Many investigators have come to the study of growth variations 
from other viewpoints. For example, a large number think of them 
in terms of pests, for economic necessity has demanded their study, 
especially in wet climates, where timber is abundant and they are 
nature's agents for maintaining an equilibrium. It is true that the 
relation of the abundance of animal life, even pests, to climatic con- 
ditions is receiving more and more consideration, but the supreme 
r61e of rain in a dry climate needs to be a matter of constant 
experience in order to bring appreciation of the relation of tree-growth 
to moisture in the Southwest. 

AFFILIATIONS 

At the outset this work was recognized as on the borderland 
between astronomy, meteorology, and botany, and as needing help 
and information from each with some expectation of ultimate return. 
To some degree this return is realized in the present volume, which 
gives for the astronomers some evidence of a real history of solar 

3 



4 CLIMATIC CYCLES AND TREE-GROWTH 

changes for many centuries, for the meteorologists certain drought 
conditions and climatic changes over a similar length of time, and 
for the botanists an opportunity for learning how vegetation reacts 
to certain phases of its environment. In addition, various problems 
of dating, such as the chronology of the prehistoric ruins of the South- 
west, have received a new approach, but solar and climatic cycles 
with an ultimate view to seasonal prediction have continued the 
central theme. 

Prediction possibility has been one of the great incentives to recent 
work upon tree-rings. There seem to be two approaches to long-range 
forecasting. One is by direct tracing of the physical causes and the 
other is by learning the history of past changes and working out 
empirical methods. Each needs the other; so the climatic history 
written in trees is doubly useful, for it may of itself give means of 
foretelling the future, if such can be found, and, on the other hand, 
if the physical causation is traced first, the derived line of causes 
must agree with and explain this known history in trees. Thus pre- 
diction will gain at once greater reliability. The last chapter in the 
book deals with the various climatic cycles found in trees. 

The effort to find a basis of seasonal prediction is the modern phase 
of an age-old problem. In our day of newspapers, calendars, and clocks 
it is hard to realize that at the beginning of prehistoric agriculture 
farmers knew little of the time of day or the time of year except as 
signs in the heavens told it to the rare man who had learned the 
language of the sky. We are now in the same stage of ignorance 
regarding yet longer cycles and hope to find our time in relation to 
them so that we may know better when and what to produce each 
season for modern needs. 

DEVELOPMENT 

With a conviction of the climatic value of tree-ring studies, one 
can see two general lines of development, roughly described as exten- 
sion in space about the world at the present time and extension in 
time to past eras. The former has economic and scientific value, 
because, in this way, climatic variations in different hemispheres, 
continents, and latitudes may, within limits, be studied, in spite of 
absence of formal instrumental records; so also the effects of mountain 
ranges, continental contours, different orientation of exposure, and 
the reaction of vegetation under different conditions. A beginning 
is made in this volume along these lines. A set of yellow pine ring 
records has been obtained from the Western States, and especially 
the Southwest, by which a large area can be reviewed and a first 
estimate made of effects such as those just mentioned. 

Similar information regarding past climates is contained in fossil 
trees. Without knowing exact dates, we can learn something about 



INTRODUCTION O 

the climatic and solar changes in various geologic periods, Tertiary, 
Pleistocene, Prehistoric, and Protohistoric. The methods and instru- 
ments developed in this research give us an improved approach to 
various types of geologic material besides fossil woods. Chief among 
these are the clay layers of de Geer and Antevs, dealing with the 
retreat of the ice-sheet, the andesite laminations of Udden in Texas, 
and the stalagmite deposits of Allison. This geologic material, with 
much more that will come to light, will not be included in the present 
volume, but will be reserved for future discussion. 

One can see that in all this we are measuring the lapse of time by 
means of a slow- geared clock within the trees. For this study the 
name "dendro-chronology" has been suggested, or " tree-time." This 
expression covers all the dating and historic problems referred to in 
the following chapters, as well as the study of cyclic variations and 
the distribution of climatic conditions. 

COOPERATION 

But with this development there is added need of information 
from other sciences. The relationship of solar activity to weather 
is a part of a rather specialized department of astronomical science 
called astrophysics. There is help which one needs from that science, 
but which one can not yet obtain; for example, the hourly variations 
in the solar constant. One would like to know whether the relative 
rate of rotation and the relative temperatures of different solar lati- 
tudes vary in terms of the 11-year sunspot period. These questions 
have to do with some of the theories proposed in attempting to explain 
the sunspot periodicity. We do not know the cause of the 11-year 
sunspot period. Here, then, is work for the astronomers. Climate 
is a part of meteorology, and the data which we use are obtained 
largely from the Weather Bureau. The observing stations are usually 
located in cities, and therefore we can not get data from proper places 
in the Sierra Nevada Mountains of California, where the giant sequoia 
lives. Considering that this big tree gives us the longest uninterrupted 
series of climatic effects whose dates are accurately known, which we 
have so far obtained from any source, it must be greatly regretted 
that we have no long modern records by which to interpret the writing 
in those wonderful trees. So far as I am aware, only one attempt is 
now being made to get complete records for the future.* 

From the botanists and ecologists we need to know the exact 
time of ring formation, the ability of the tree to conserve moisture 
against the day of drought, the soil-moisture gradients at different 
months, the different action of the tree in putting on a different color 
of wood in the spring and autumn growth. 

In dating problems, this study has developed another important 

*CoJ. John R. White, in Sequoia National Park. 



6 CLIMATIC CYCLES AND TREE-GROWTH 

contact. The rings in the beams of ancient ruins tell a story of the 
time of building, both as to its climate and the number of years 
involved and the order of building, perhaps ultimately the date of 
building. All this is anthropology, and much data from the archae- 
ologists will help in identifying the rings in beams and supply valuable 
climatic records of long-past times. 

ACKNOWLEDGMENTS 

The author's acknowledgments with thanks are most cordially 
tendered to many sources of help. First of all, to the Carnegie Institu- 
tion of Washington for bearing the expenses of publication and for 
the yearly appropriations through its Division of Ecological Research, 
to aid this study by securing suitable help and occasional field trips and 
instruments ; and equally to the University of Arizona for so reducing the 
author's teaching hours as to permit this investigation; to Mr. Clarence 
G. White, of Redlands, California, for the White Research Fund, 
which permitted the building of the periodograph in its latest and 
most effective form; to Major L. F. Brady, whose interest in the 
Flagstaff "buried trees," in prehistoric beams, and in the "burnt 
trees" has brought in valuable material; to Dr. F. N. Guild, who 
identified and described the white crystals found in buried trees and 
named the mineral "fiagstaffite"; to Vilhjalmar Stefansson and the 
Canadian Geological Survey for specimens from the American Arctic; 
to Dr. W. P. Wilson and the Commercial Museum in Philadelphia for 
access to the fine sections of Brazilian pines; to Mr. Percy J. Brown 
and nephew, of Scotia, for their hospitality and cordial help in collect- 
ing coast redwoods; to Mr. R. E. Burton for help with the Santa 
Cruz redwoods; to Dr. E. S. Miller, of Flagstaff, Arizona, for help 
with "buried trees "and in collecting the group called "Flagstaff 
Northeast"; to the Whitesides, at Calaveras Grove, California, for 
opportunity to compare the growth records there with those at the 
southern sequoia groves; to Col. W. B. Greeley, of the U. S. Forest 
Service, and Mr. Stephen Mathers and Mr. Arno Commerer, of the 
National Park Service, for letters of permission to secure material 
in such places; to the many officials of the U. S. Forest Service who 
have helped me, especially Mr. G. A. Pearson, of Flagstaff, through 
whose efforts the 640-year yellow pine was found and who has secured 
many borings for me; to Mr. T. A. Riordan and Mr. M. J. Riordan 
for the largest yellow pine section yet obtained in northern Arizona, 
and many other kindly bits of assistance; to the National Geographic 
Society and Mr. Neil M. Judd, director of its field work at Chaco 
Canyon, and to Dr. J. A. Jeancon, of Denver, and Dr. A. V. Kidder, 
of Andover, Massachusetts, also to Dr. Clark Wissler, of the American 
Museum, and Mr. Earl H. Morris, for the trip to Aztec and entertain- 
ment at Chaco Canyon and extensive contributions to the large 



INTRODUCTION 7 

collection of prehistoric beams; to the Toll Roads Company and to 
Dr. W. S. Adams, of the Carnegie Institution, for permission to collect 
samples on Mount Wilson; to Mr. E. W. Griffith, of Las Vegas, 
Nevada, for a trip to the Charleston Mountains; to Mr. N. P. Wheeler, 
jr., for the trip and collection of white pines near Endeavor, in north- 
western Pennsylvania; to the forest supervisor at Klamath Falls, 
Oregon, and Mr. Emanuel Fritz, for collections in Oregon and northern 
California; to the directors and curators in the American Museum, 
the Metropolitan Museum, and the Museum of the American Indian, 
New York; Peabody Museum, Cambridge; National Museum, Wash- 
ington; and the Field Museum, Chicago, for cooperation and help 
in measuring specimens; and especially to Dr. John C. Merriam, 
President, and Dr. F. E. Clements, ecologist, of the Carnegie Institu- 
tion, for their continued help and interest in this line of investigation. 

PREVIOUS WORK 

The first publication by the author was in 1909, in the Monthly 
Weather Review. This was followed by other articles until the whole 
was summarized in 1919 in a volume with the same title as the present 
one and published under the same auspices. At that time identifica- 
tion and measurement had been made of about 75,000 rings in some 
230 different trees from the States of Oregon, California, Arizona, 
Colorado, and Vermont, as well as from England, Norway, Sweden, 
Germany, and Bohemia (near Pilsen). That volume dealt with 
studies upon the yellow pine about Flagstaff, Arizona, climatic con- 
ditions there, the yearly identity of rings, cross-identification, time 
of year of ring formation, number of trees necessary, the actual collec- 
tion of yellow and Scotch pine and sequoia samples, methods of 
curve production, correlation with rainfall and with solar activity, 
and cycles and methods of determining them. The present book 
opens with the development of technique in collecting and treating 
specimens. 



1 



II. TREE SELECTION 

Rings of trees have told many stories of the past. By their mere 
enumeration the historian has built up our realization of great events 
injhuman progress; by more careful counting the forester has dis- 
covered the dates of ancient destructive fires; by changes in the rings 
ecologists have determined historic changes in lakes and rivers and 
settled questions of legal ownership. The present study of climate 
and solar activity uses the accurate dating and width of rings over 
wide geographical areas and into times long past for several purposes, 
but chiefly to derive an understanding of that immensely complex 
process by which climatic forces reach the earth and distribute them- 
selves about it. This, it is hoped, will eventually lead to safe long- 
range prediction of climatic conditions. In the present approach to 
the subject, the recent development of technique is given first, and 
this chapter deals with the selection of trees for climatic study. 

SPECIES 

Pines — The western yellow pine is perhaps the best tree for climatic 
studies, on account of its precision and length of record and its wide 
distribution. It is normally a dry-climate tree and does well in a 
sandy soil, for its thick bark prevents evaporation from the trunk 
and thus enables it to live when other trees could not survive. Thus 
it endures relatively trying conditions and has little competing vegeta- 
tion, so that the Arizona forest is said to be the largest "pure" stand 
in the country. It can be injured by too much moisture in the soil, 
and draining then improves it. Its age is very favorable, reaching 
over 500 years. It is commonly free from burns and defects and its 
rings are very readable. The immense area over which the yellow 
pine grows adds to its value in this study, as its use avoids the com- 
plexities arising from the use of different species. For all these reasons 
it is considered the standard tree. 

The Scotch pine of north Europe is very similar, but not usually 
so large. However, this is because the European regions have been 
cut over so much that very old trees are rare. The white pine in the 
Appalachian Mountains cross-identifies very well. The pines in 
eastern Massachusetts are less satisfactory, probably because the 
region is too much cultivated. Very old hemlocks in the Green 
Mountains of Vermont have rings extraordinarily like those of the 
western yellow pine and almost as perfect in cross-identification. 

White pines in the Yellowstone are good, and a few white or limber 

pines near Flagstaff give records that are readable, but the locations 

in which they grow are so rugged and variable that a complete test has 

not been made of them. The foxtail pine at high altitudes sometimes 

8 



TREE SELECTION 9 

reaches a great age, but its rings are more complacent than those of 
the yellow pine. It reminds one of a cedar. 

Sugar pine — Sugar pines are fine, large trees, but the rings are 
large and the age is often disappointing. The distribution is much 
more limited than the yellow pine; from which one assumes that it 
will not stand so great a variation of moisture. Ring records of this 
species on Mount Wilson resemble very closely similar records from 
the adjacent yellow pines. Like the Douglas fir, it is a good occasional 
substitute for the yellow pine, but is far from its equal as a standard 
tree in southwestern climatic study. Substitute trees have given so 
many cases of satisfactory records that one feels it always worth while 
to use some other tree than the yellow pine where such standard trees 
are scarce. 

Douglas fir (spruce) — In the Arizona Mountains this tree borders 
the pine belt on the upper, which is the colder and more rainy side. 
It mixes with the yellow pine to a small degree and is the first choice 
as substitute when the pines are infrequent in any site. The trees, 
even if bigger, are apt to be younger, with larger growth each year. 
The rings are usually well marked and free from errors and cross- 
identify perfectly with neighboring yellow pines. It is somewhat apt 
to exaggerate climatic influences. 

Other spruces — The Sitka spruce of our northwest coast (tested 
in Oregon and Washington) has heavy, emphatic rings of a complacent 
sort and so far has not seemed a desirable tree. It grows to exceedingly 
large size. A fine specimen some 9 feet through, in the American 
Museum in New York, gives a good idea of what it is. This particular 
specimen exhibits some very unusual spiral gross-rings whose origin 
it would be interesting to determine. This spruce grows at low, well- 
watered levels near the coast, and so its value as a climatic record is 
probably low. 

The Engelmann spruce of high altitudes is even less valuable in 
this respect. It grows at elevations over 8,000 feet at Pike's Peak 
and at 10,000 on the San Francisco Peaks (Arizona). Its rings have 
very little variation and do not cross-identify with neighboring pines 
and Douglas firs. Owing to these characteristics it has practically 
no value as a climatic record. 

The European spruce, Picea excelsa, is much better. While more 
complacent than the very satisfactory Scotch pine there, it does show 
good ring variations which can be dated and in one or two special 
cases give a remarkable record of solar variations. Such is No. S 14 
from southern Sweden, whose photograph is given here (see Plate 9) 
because it did not come in time for insertion in the first volume. Its 
curve of growth was given in Volume I, page 75, figure 22. It is 
therefore unusual and interesting. 



10 CLIMATIC CYCLES AND TREE-GROWTH 

Sequoias — In this review of western trees the mountain sequoia 
(Sequoia gigantea) easily takes a leading part in company with the 
yellow pine, for besides its great age it has a fundamental feature of 
greatest importance, namely, cross-identification over large areas. 
In this character we recognize climatic influences. The ring-growth 
in the big sequoia is not so sensitive as in the yellow pine, and perhaps 
any individual tree is a little less certain to identify with its neighbors, 
but yet cross-identification is very sure in that species and extends 
through all the mountain sequoia groves from Calaveras on the north 
to Springville on the south, 200 miles. The southern groves, which 
yield the best results, give a record obviously similar to that of the 
yellow pines in neighboring locations. It is true that the sequoia 
needs a large moisture supply, probably more than it usually gets, 
but its location is so high on the mountains that the winters com- 
pletely interrupt the growth and therefore make the record in the 
rings very reliable as to its annual character. The great age of this 
tree gives it a second fundamental value. It is astonishing, for ex- 
ample, to find over considerable areas similar identifiable rings near 
1,000 b. c Further study upon the sequoia will improve our knowl- 
edge of the normal growth-curve in relation to age, so that we can by 
extrapolation tell with some precision what the climate was 3,000 
years ago. This requires many corrections, such as that for flare of 
the base, for slanting rings, and lor the indentations of the trunk which 
come from root relationship. All these factors differ so much in indi- 
vidual trees that it would seem profitable to study each tree specially, 
and in recent collecting I have made notes about every stump and have 
distributed the ages more carefully. (See Huntington, 1914.) 

Coast redwood — The coast redwood (Sequoia semper •virens) has 
been a disappointment, because after most careful tests it has failed 
entirely to show cross-identification. This is undoubtedly due to its 
climatic environment. Various attempts to make use of this tree are 
described below (Chapter VI). 

Junipers — The junipers and cedars are important in this review, 
because in Arizona mountains they border the yellow pines on the 
lower and therefore the warmer and drier side. As one ascends from 
the desert to the forest areas, the first dark-green rounded trees are 
the junipers of several different species. The growth of the juniper is 
slow and the rings are often attractive, but for actual use disappointing. 
One species branches at the ground and so seems impossible; another 
has deep vertical indentations in the trunk, with erratic rings. The 
growth can rarely be traced from lobe to lobe of a cross-section. Often 
the rings condense so that identity is hopelessly lost.* The more 
promising species is the pachyphlcea or alligator-bark juniper, which 

* Some successful work has recently been done on the junipers. 



TREE SELECTION 11 

grows close to or in the pine belt. Its rings are apt to be complacent, 
with considerable difference in mean size due to locality. From the 
average rate of growth of junipers measured near Cibecue, 500 to 700 
years would seem to be the usual maximum age of this tree. 

This species has one idiosyncrasy which often rules out an attractive 
tree. A vertical half may die and the other half live. This may happen 
to the trunk and follow up some of the larger branches nearly to the 
top of the tree. Close to Elden Spring at Flagstaff is a juniper of this 
sort which is 4 feet through east and west and is still growing actively 
in those directions, but north and south it is only a foot through and 
completely dead. The alligator-bark juniper is more promising than 
the other species and may become a valuable tree on more complete 
investigation. 

The cedars are somewhat like the last-mentioned juniper. They 
are rather complacent, but do show some variations. The west 
coast cedars take a good deal of water-supply. Some extremely large 
ones are occasionally found, but they have not seemed promising. 
The rings are generally larger than the sequoia rings and for the same 
size the trees are not so old. Many cedars growing in the vicinity 
of the sequoias have been examined and the ring record is considered 
below the big tree record in quality. 

Oak and other hardwoods — The oak is less generally distributed 
in the Southwest than the yellow pine, but there are large and im- 
portant areas over which it is the available tree. Various samples col- 
lected seem very promising, but it has not been available extensively 
in the form of stumps and it is too hard to bore, so no final tests can 
be reported here. Kapteyn's first work in the Rhine Valley was on 
oaks, and in the last few years (1921) Professor William J. Robbins, 
of Columbia, Missouri, has traced a fine relationship between oaks and 
spring rainfall. This tree was used in the Swiss lake dwellings, and 
fossil oaks are very common, showing some of the best ring records 
to be found in museum specimens. Undoubtedly it is a valuable tree. 

Beech rings in northwestern Pennsylvania show good variations 
and seem very promising. This is well to keep in mind, because there 
are great beech forests in South America whose rings may contain 
important climatic information. 

Tropical hardwoods have been examined in museums in large 
numbers. The annual rings are mostly very hard to make out and 
naturally that is what we would expect where the trees have over- 
abundant rain and sun. Yet there are pines from tropical areas 
whose rings look very attractive and well worth a careful test for 
climatic effects. They grow mostly at higher levels. Two Araucanian 
pines from southern Brazil, showing 500 years of age, were measured 
in the Commercial Museum at Philadelphia. Their variations looked 
very attractive, but there was no success in finding cross-identity. 



12 CLIMATIC CYCLES AND TREE-GROWTH 

Cedar of Lebanon and archaeological material — This cedar is 
chiefly found in mummy cases, which from the earlier dynasties show 
beautiful ring systems, very pronounced but somewhat complacent. 
The wood is not so good as yellow pine or sequoia, but as approximate 
dates are known its records are valuable. 

The prehistoric ruins of the Southwest have large numbers of pine 
and fir logs used as beams. These offer the finest records and a very 
valuable collection has been made. Even the charred ends of beams 
that remain in some walls of burnt-out kivas give perfectly good ring 
records which permit the "relative" dating of the construction period. 
Juniper, cedar, and pinyon have been used in the same ruins and many 
sections have been saved, but so far little relative dating has been done 
on them. Engelmann spruce also occasionally is found, but it has failed 
to be of value. Several cottonwoods give too short sequences to be 
worth while. Certain buried pines from the vicinity of Flagstaff give 
very fine ring records with other interesting features. 

LOCATION OF TREE 

Regions which have been recently cut over will offer the best 
facilities in getting good specimens from the stumps. A full day or more 
may well be spent in marking the stumps from which pieces will be cut 
later by workmen. This selection is very important, for one wants a 
group that will cross-identify and at the same time will fully represent 
the forest and the general locality. 

Homogeneous area — One needs, in the first place, to collect from 
a homogeneous area, that is, an area in which the various trees have 
somewhat similar conditions, enough to give similarity in rings, for 
on this recognition of the same rings in each depends assurance of 
climatic effects in the trees and reliability of dating of rings. To limit 
one's self to a homogeneous area means that the group will not extend 
to opposite sides of a large mountain. In northern Arizona differences 
of a few hundred feet in altitude do not usually affect the rings, but 
differences of 1,000 or 2,000 feet do sometimes affect them. Westerly 
or southwesterly exposures are somewhat preferable, as that is the 
direction from which the storms come and there can be no "shadow" 
or other local effect. 

Wide sampling — On the other hand, the group should not be con- 
densed, but should extend a good portion of a mile at the least, so that 
no alteration can arise from some special condition affecting a part of 
the group. 

Grouping — The tree bored, or the stump cut, is better if not near 
other trees. Trees under 10 feet apart are apt to have an effect one upon 
another by undue shading or appropriation of moisture. This causes 
eccentric growth of the rings, throwing the major radius away from the 



TREE SELECTION 13 

center of the group. Such eccentricity is rarely harmful to the ring 
sequence unless very conspicuous, but it may mean erratic or slanting 
growth and therefore is to be avoided as a rule. While the Arizona 
pines are naturally isolated, the sequoias are habitually close-grouped; 
but in spite of this the latter tree rarely shows any effect that can be 
attributed to nearness of other trees, unless two are almost in con- 
tact. But in the coast redwoods close grouping is doubtless an 
important cause of its failure to cross-identify. 

The big tree is surrounded by dense vegetation in the basins and 
loose vegetation on the ridges; the coast redwood has a jungle about 
it; the yellow pines, however, wherever they grow, have sparse or 
actually deficient vegetation about them. 

Ridge and basin selection — This is a question of soil moisture and 
underground drainage, most important factors in the life of the tree, 
for while other influences may alter groups of rings and completely 
spoil parts of the record, the moisture-supply in the soil may change 
the character of the entire record or even make it totally useless. The 
evident topographic features which control the situation are of course 
hill and valley, but to make it more specific by naming the extremes, 
it is called ridge and basin. Ridge and basin sequoias cross-identify 
perfectly, but there is a great difference in their immediate response to 
climatic changes, so that the ridge trees show much smaller average 
growth with vastly greater differences from year to year. This goes 
so far that the ridge trees nearly always omit many rings in the radius 
one chooses to study. Only by accurate cross-identification can these 
omitted rings be determined and correct dating carried past them. 

In the yellow pines, ridge and basin contours have the same effect, 
producing quick-growing, complacent trees in the latter and slow- 
growing, sensitive trees in the former. With these facts in mind one 
can usually pick the kind of tree desired. 

Bedrock and soils — Lavas and clay soils give usually a small 
complacent growth to the Arizona pines, while limestone and the 
porous soil above it give more sensitive growth, which may be increased 
in size by a richer soil. 

Pines and altitude — The Arizona yellow pines at low levels, such as 
5,000 feet, are so sensitive to rain that rings are frequently doubled 
by the two rainy seasons. This characteristic nearly disappears in 
1,000 and 2,000 feet of greater elevation, where the most usable 
records are found. At still greater heights the accuracy of the rainfall 
record diminishes, as soil and air moisture are more permanent and 
the tree in its type of ring record becomes more like the California 
yellow pine and sequoia. 

East and west mountain slope — In the southwestern part of the 
United States, the winter storms coming from the west supply nearly 



14 CLIMATIC CYCLES AND TREE-GROWTH 

all of the growth-moisture for the trees. The result is that the east 
and west sides of a large mountain have a distinct difference in climate 
which shows in the trees (see shadow effect, p. 108). At corresponding 
levels the west side is wet and the east side is dry. Around the San 
Francisco Peaks, in northern Arizona, the pines extend to 1,000 or 
1,500 feet lower elevation on the west than on the east. Pines on 
westerly slopes are to be preferred as less likely to be altered by local 
conditions. 

North and south mountain slope — Snow lingers longer on north 
slopes, and pine trees are able to live under such conditions at lower 
altitudes. But in the middle elevations of the pine belt no sensible 
difference has been noted in ring record between minor north and south 
slopes. 

CONDITION OF TREE 

Lightning scars — In standing timber this commonly appears as a 
white streak from top to bottom of the tree, about 1 inch in width 
where the bark has been blown away and the wood revealed. The heat 
of the electric flash has suddenly vaporized the sap and exploded the 
tree along this narrow line. This usually heals and has no important 
effect on the climatic record in the tree. The scar is easily recognized 
on the stump. It is very common in the "buried trees" found in the 
valley terrace above Flagstaff, which doubtless means that summer 
thunderstorms were more common in that particular past climate 
than they are now. Lightning scars are rarely seen in petrified wood, 
but the writer has a photograph of one in a beautiful specimen from 
Tertiary levels in Yellowstone Park. 

Injured and fire-scarred trees — The major injury to western trees 
is from fire. This is not always caused by the careless camper or 
«moker, for the greater number of forest fires come from lightning. 
A single summer storm at Flagstaff has been seen to start fires in four 
different trees. In a precipitous country it is the up-hill side of the 
tree which is more likely to have fire injury, for it is the brush and 
leaves and needles collected there which hold the fire till it injures the 
tree. The fire scar is a large burnt area covering from 10° to 150° of 
the circumference and extending from 3 to 20 feet or more above 
ground. The tree may recover by covering a small area with new 
growth or by abandoning all attempts to reclothe the burnt section 
and using only the root system on the normal side. 

Different trees and fire — Fire injuries rarely give trouble in the 
yellow pine, for they are largely on nearly level ground and there is 
little vegetation about them. Hence, there is little accumulation of 
rubbish and a general fire does not finger about an individual tree. 
The sequoias represent an enormously greater interval of time and so 
.are more likely to show fire scars. Their ages are from 700 to 3,000 



Carnegie Inst, of Wash. Pub. 289, Vol. II (Douglass) 



fU 





wtmm x 



A. Fire injury on D-12 (stump) showing repair and gross rings and 
inclosed bark 




B. Center of oldest Sequoia, D-21, showing ring grown in 1305 b.c. ; three 
pins stand at 1300 b.c. 



TREE SELECTION 15 

years, compared with 200 to 500 for the pines. The sequoias also 
grow close together, and in the basins are closely surrounded by other 
vegetation. So fire once in them lingers and injures the tree. Amongst 
thousands examined the uninjured trunk has been very rare, perhaps 
less than 1 in 10, as one looks on top of the stump and sees the history 
of each tree. The large groves of coast redwood show similar history. 
Though the custom of burning over the area right after cutting may 
lead to overestimation of the number of ancient fires, the impression 
is gained from hundreds of stumps that large fire injury is very nearly 
as common as in the giant sequoia. 

In tree selection the effect of a lightning scar is negligible. The 
effect of a fire which kills small trees about but does not externally 
injure the tree under examination is to cause a slight possible diminu- 
tion in size of rings. In this connection one remembers that fires are 
more frequent in times of drought and hence exaggerate climatic 
effects already in the trees. But the effort of a tree to repair a large 
burnt area changes the ring-size for some distance from the injury and 
sometimes all about the tree. Hence trees showing large fire injury should 
not be used. 

COLLECTION PURPOSES 

In securing records of climate in trees, necessarily length and 
accuracy of record are the two primary considerations. In the previous 
pages we have dealt with accuracy alone; now we deal with length, 
always modified by the necessity of preserving accuracy also. 

Cycles and secular changes — The original thought in this study 
emphasized the tracing of cycles. These are found in relative ring- 
sizes which can be taken almost at once from the trees without a 
knowledge of the absolute rain or climatic equivalent. Perfect dating 
was absolutely necessary and all specimens have received the most 
careful laboratory handling. It was found by early tests that no especial 
gain was made by using large numbers of trees (Vol. I, pp. 21-22). 
But when Huntington studied the big tree for absolute values and 
secular changes, he did his work on the stump and obtained material 
which served his purpose without accurate dating. He used many 
specimens of all ages in order to work out a compensation for age, for 
that was fundamental. 

Best collection methods — To allow for the needs of each of these 
purposes the best collection includes, first, long records; second, a few 
younger trees for the sake of certainty in dating the older trees if 
recent rings are compressed and doubtful and in order to develop a 
compensation formula for age of tree; and third, borings in the outer 
parts of living trees in order to get present-day climatic comparisons 
and to be perfectly sure of the ring of the current year, which sometimes 
fails to show on the stump. 



16 CLIMATIC CYCLES AND TREE-GROWTH 

Long-record trees — (1) Pines. If very large living pines are in 
moist valley-bottoms, they are not likely to be of maximum age, 
that is, over five centuries; but if they are near 60 inches in diameter 
and growing on a ridge or hillside, especially above a dry valley, they 
are likely to contain a valuable record. Of course, in such cases one 
checks the estimate by a core from the increment borer. (2) Sequoias. 
The oldest sequoias are not close to running water nor yet on exposed 
ridges, where stress of storms does not permit great age, but they are 
somewhat between these situations and usually near, though not at, the 
higher levels of the grove. This description applies well to the 3,200- 
year tree at Converse Hoist and the 3,100- and 3,000-year trees at 
Enterprise. A 2,800-year tree at Converse Hoist was nearer the top 
of a low ridge than one would have expected. A number of 2,200-year 
trees were well outside and yet not far from the thickly covered swampy 
basins, and they extended up the valleys to the highest levels of the 
groves. In the lower levels the trees were apt to have a large supply 
of ground water and some very large trees had only 1,500 to 2,000 
years of age, such as the "Big stump" at Wigger's (General Grant 
Park) and the Dance Hall stump at Calaveras Grove. 

Collection for age compensation — Samples for this purpose must 
obviously be taken from the immediate vicinity of the old trees whose 
records are to be checked, and in the same topography. 

Climatic comparison — In collection for climatic comparison, one 
uses the general principles of selection already enumerated, remember- 
ing that one gets little if anything from young trees. Mature trees 
are much preferred, and even the largest and oldest, for in such cases 
the 9 or 10 inches of core cover a great number of years. On the 
other hand, very slow growing trees from the tops of dry ridges may 
be impossible to date without some neighboring younger trees, and 
it is safe nearly always to include a very few younger trees to assist in 
this operation. Trees very near a road are apt to be erratic from injury. 

Age estimates in sequoias — Age estimates are a necessary part 
of collecting, especially in sequoias. The best criterion is the size of 
the outer rings, coupled with the total diameter of the tree. A promis- 
ing tree should be over 20 feet in diameter above the bulging base, 
or near 25 feet at the very maximum. The rings at various places in 
the outer parts should get down to a few tenths of a millimeter or 
about a hundredth of an inch. On most of the very old trees there is 
a burnt space in which a few chips or bits of charcoal will give a sample 
of the rings. An increment borer is still better and may be used through 
a thin place on the bark of a living unburnt tree. The largest tree, 
showing over 30 feet in maximum or bulge diameter, if near running 
water, is not likely to add much to our climatic record. But if such a 
tree is on a dry hillside its age is worth investigating, and if it still 
promises well, some apparatus for boring it to the center could be devised. 



III. RADIALS 

SELECTION 

An essential part of this study of climate and trees has been the 
laboratory work on the rings, by which the actual wood from the tree 
is placed under microscope and measuring-machine. In this way 
specimens from different trees may be compared together and an 
accuracy reached which would be hopeless in work on the stump. 
By laboratory means, cross-identification and correct dating are 
obtained before measuring and the measuring can be done to any 
desired accuracy which the rings permit. Hence it is essential to secure 
ring specimens which represent the tree, to get them to the laboratory 
without injury, and then preserve them in such a way that they can 
be used over again or referred to subsequently for any desired purpose. 

Definitions — It is obvious that such ring specimens must be cut 
across the rings in order to display the proper sequence. The ideal 
form, therefore, is a radius of the tree, carrying an unbroken series 
of rings over all parts of the tree's history which are worth while. 
Such pieces are here referred to as tree-samples, ring records, radial 
pieces, or simply radials. Of course, they may take different forms, 
depending on various conditions of collection; for example, whether 
they come from living trees, fallen trees, or stumps. 

LIVING TREES 

The main point in sampling living trees is to get a short radial 
sequence of rings without injury to the tree. The best instrument for 
this is the Swedish increment borer, which will be more fully described 
in a subsequent chapter on instruments. These borers will not go 
into hard woods nor even into junipers, but they work well in pines. 

Direction of boring — If the tree is on a steep hillside, it is usually 
more convenient and customary to bore on the up-hill side. Theo- 
retically there could be a difference in the rings between the up-hill 
and down-hill side of a tree, but no such difference has been noticed. 
Other things equal, it is well to eliminate the possibility by being 
consistent throughout a group. If the ground is generally free from 
steep inclination, one should adopt a certain compass direction and 
use that consistently in the group. Early investigation showed about 
Flagstaff a slight average increase of growth on the north or northeast 
side of a tree, due to lingering of snow in the shade of the tree, but this 
is probably of little or no importance in radial selection. 

Height above ground — Height from the ground, if well below the 
branches, has not been found to introduce error. So far as observed, 

17 



18 CLIMATIC CYCLES AND TREE-GROWTH 

the differences at different heights are less than the differences between 
different trees. Of course, in most cases the differences are practically 
none at all. This subject of taper study or vertical uniformity will be 
treated on a later page. A boring within a foot of the ground makes 
one feel that complex and difficult corrections are needed because of the 
root influence, and the ring record therefore is inferior. On the other 
hand, if the boring-hole is made over 2 feet from the ground, it 
may injure slightly the value of the tree for lumber. The average 
height of pine stumps about Flagstaff is 16 to 20 inches, sometimes 
going to 2 feet. The lumberman knows that interior defects increase 
toward the root, and there is always a little waste at the lower end of 
the butt log. In choosing the exact spot to bore it is better to try a 
slightly projecting part of the trunk, for there is less danger of encoun- 
tering absent rings which might render dating difficult. One must be 
careful in boring fallen trees to note whether they still have roots in 
the ground and are dry or moist. If they are still rooted or not thor- 
oughly dried, the sapwood may be distorted with irregular growth or 
irregular swelling from moisture. 

Root rings — Ring sequences have been identified from roots of 
trees and in some cases such records seem usable. These, however, 
have never been included in the averages, from the feeling that root 
rings, even in large branches of the root, must be subject to other 
conditions than the trunk and may not be consistent. Sometimes, 
in well-watered pines, early rings in the lower trunk near the root may 
be very large.* 

Crown rings — Rings near the top of the tree and in larger branches 
show close similarity to rings in the lower trunk. Though their 
actual size is smaller and sometimes microscopic, the sequence of sizes, 
of the tree record, is nearly the same (see fig. 1, p. 24). 

Boring the sequoia — Using the increment borer on the sequoia 
has rarely seemed worth while, except for some special purpose, such 
as tests on young trees for infancy rings, estimates of age, and so 
forth. The reason is the enormous thickness of bark of the sequoia, 
especially in the lower 15 feet, and the distortion of rings due to bulges 
in the same region. With a ladder one could get useful specimens. 

The i-inch tubular borer — The tubular borer so far has not been 
satisfactory on living trees, not because it hurts the tree but because 
it is slow and difficult in operation. An 18-inch core from a 350-year 

*This was observed in a tree which once stood in the flat south of the county hospital at 
Flagstaff, about 2 miles north of town. The tree was cut down in the 1880 's and was renowned for 
its size. Recently Mr. L. F. Brady copied on paper the rings in the stump, which was badly 
burned. When I saw it, the stump had been blasted out and thrown away, but fragments showed 
extremely large and complacent rings near the root. The dating was uncertain, but it was prob- 
ably nearly 500 years old at time of cutting. 



RADIALS 19 

tree in the lava-bed near Flagstaff took nearly two hours of very hard 
work. When it is needed, no doubt a suitable borer will be easy to 
construct. 

FALLEN TREES 

The chief work on fallen trees was done in the Calaveras Grove of 
sequoias. The bark of these trees lasts 10 years or so after the tree 
has fallen. The sap wood weathers off in something over half a cen- 
tury. Heartwood has lasted a hundred years in the open air, but in 
the case examined the wood was badly decayed and little of it was 
left, as shown in Plate 2. It has been a disappointment not to find 
logs lasting far longer, for example, a thousand years; for if very 
large ones could be found they might have very old ring records. 
Apparently even the wonderful qualities of the sequoia sap will not 
preserve the wood indefinitely. Fallen trees give the chance of boring 
at any height and from that arose the vertical uniformity or "taper" 
tests given below. 

In the Calaveras Grove there were three classes of fallen trees, 
so far as dated records were concerned: (1) old tree- trunks without 
sapwood, so that the date was unknown; (2) trees showing sap wood, 
with approximate date of falling; and (3) those whose date of recent 
f ailing was known. So to insure correct dating, all three were included. 
Thus an overlapping group was obtained, which by cross-identification 
produced correct dating for the Calaveras trees. But all this care 
proved unnecessary, for the first radial examined, as well as all the 
rest, readily dated in terms of the trees in the southern groves. 

STUMPS 

Collection from stumps permits many forms of which the full 
section is only possible in the case of small trees. Thus full sections 
have come from the white pines of the American Arctic and from the 
beams of the ancient ruins. At the start, full sections were made of 
the early Arizona yellow pines, but they have proved so unwieldy 
and difficult to provide space for that even from these radial samples 
have been cut, which give the ring sequence from center to outside. 
So methods of collection necessarily adapt themselves to the size of 
the trees. In the vast majority of cases a piece is cut from the stump, 
and that process is described below. 

Shape of stump — In felling a tree a notch is first cut on the side 
toward which the tree leans and will fall. This undercut goes perhaps 
one-fourth way through. In big trees it becomes large enough for 
men to stand up in. Then a two-man saw is started in horizontally 
from the opposite side at a slightly higher level. As the saw enters the 
tree, the weight of the tree will pull away from it and not make it 
bind. Sometimes the tree is leaning so heavily that as the saw gets 



20 CLIMATIC CYCLES AND TREE-GROWTH 

deep into the trunk, the strain on the remaining wood is tremendous 
and it cracks badly in lines parallel to the saw. If its own weight does 
not keep it from binding the saw, steel wedges are driven in the cut 
to force the tree up on that side. The tree usually begins to fall 
some time before it is completely cut from the stump, the portion that 
is uncut breaking off at the level of the undercut. The stump then 
shows the sawed surface for two-thirds of the diameter on one side, 
the chopped surface of the undercut a foot or two lower on the other 
side (in the big trees), and between these a broken and splintered 
space where the wood broke in falling. Sometimes the tree does not 
fall of itself when the saw is approaching the undercut, and then 
instead of sawing it completely in two, which would be dangerous, 
sticks of dynamite are placed in the remaining attached portion and 
the tree blown loose. This is apt to blow the stump to pieces, as 
happened with D-18 of the early sequoia group. That sample was 
therefore cut from the end of a log which had been 50 feet or so above 
the ground. So nearly all stumps have a flat top, which will exhibit 
from a little over one-half the diameter to more than three-quarters. 
This restricts the choice of radius a little, but reduces the amount of 
sawing in making the cuts for the radial piece. 

Selection of radius — In visiting a cut-over area with multitudes 
of stumps, the first consideration is the apparent excellence of the 
rings and the ease of cutting a radius which contains good readable 
ones. In the Arizona pines this gives very little trouble. In these 
trees the radius chosen and marked merely fulfills consistency regard- 
ing points of the compass and contour of ground, and avoids fire-scars, 
lobes, and knots in the stump-top itself. The piece cut out very often 
takes the whole diameter. In the sequoias perhaps only 10 per cent are 
without defects, and the inspection of stump-tops becomes an impor- 
tant matter requiring from half a day to a couple of days. Deep fire 
wounds in healing often inclose large masses of bark, and frequently 
such scars have a considerable area of sapwood which has never 
turned to heartwood. Such defects are always interesting for the 
history they tell and are easily avoided in picking a radius. This 
appears in the photograph of sequoia D-12 in Plate 1. 

One of the greatest difficulties with small fire-scars is the extensive 
break they sometimes cause in the continuity of the rings. The fire 
so alters the growing layer that for some distance away from the burnt 
area the wood will crack and it may be very hard to say whether the 
crack is within one annual ring or between two. Lumbermen say 
that this cracking or checking takes place in the living tree. It is 
attributed sometimes to temperature changes — frosts in the weakened 
wood — and sometimes to wind. At any rate, in a weathered stump 
such a crack becomes worse and makes it difficult to use otherwise 
good material. In such cases it is always best to cut a separate small 



Carnegie Inst, of Wash. Pub. 289, Vol. II (Douglass) 




to 



A. Weathering in 60 years, CV-4; bark gone, sapwood mostly gone; 
Calaveras Grove 




B. Weathering in 125 years; CV-3, sapwood and center entirely gone; 
Calaveras Grove 



RADIALS 21 

radial piece extending a hundred years or more on each side of the 
questionable years, from some other perfect part of the stump. This 
new piece bridges over the doubtful point. It is just such procedure 
as this which makes the dating entirely reliable. Knots or buried 
branches give practically no trouble, except at the very center. The 
lower parts of a sequoia whose bark has turned to the notable tan 
color of youth seem to have no branches. They probably all disappear 
as the rings lose that immense size called the "infancy" stage. So in 
selecting a radius for cutting it is highly important to escape gross- 
rings, lobes, and fire-scars. Items to be recorded are the length of 
radius, bulges or slope, direction and amount of slope of the ground, 
and neighbors. If the tree has grown eccentrically one would slightly 
prefer an average radius if the rings are not too much inclined. Bulges 
as a rule are below the level of cutting, but they may affect the slope 
or vertical inclination of the rings from the enlargement they produce 
in the base of the tree. In recent collections the slope of the outside 
has been measured with a simple inclinometer. 

The v-cut — Even in small trees the v-cut illustrated in Plate 3 
is now the standard form found practicable. Such small pieces are 
v-shaped or triangular in cross-section and made by two slanting 
cuts with a saw, meeting at a depth of 1 to 6 inches below the surface. 
With a long saw on large stumps the slanting cut is made by driving 
two spikes at a slant into the stump top, placing a board against the 
spikes, and resting the saw against the board. 

The size and weight of the radial piece cut out depends on the 
spacing of these cuts. Two inches is taken as the standard practical 
width and depth in big trees. If the v-cut is made from a weathered 
stump, as is usually the case, the cracks in it allow it to drop to pieces 
as the saw releases it. To aid in fitting these together the distance from 
the bark in inches is marked on each piece as it comes loose. These 
pieces are collected by an assistant who accompanies the sawyers and 
are all put in one bag, which is marked with the radial or tree num- 
ber. These small bags are finally collected in a large canvas bag for 
transportation.* 

PREPARING THE RADIAL 

Arrived at the laboratory, the pieces are taken from the sacks 
and carefully fitted and glued together and wired or screwed to a 
right-angle mount of standard size which permits stacking. This 
mounting consists of a base and back, each 4 inches wide by 8 feet 
long, 1-inch wood, with heavy square end-pieces. These mounts, 
being all of the same size, will stack one on top of another against a 

♦When this work is done by a lumberman who can not bother with bags, the spacing of the 
cuts should be wide enough to make the specimen hold together. 



22 CLIMATIC CYCLES AND TREE-GROWTH 

wall or with very slight bracing, so that at a glance one may look over 
the entire collection. 

The original surface of the stump is placed downward in the mount- 
ing, thus showing the freshly cut surfaces, which at a little distance 
below the stump-top are in better condition. One or both of these 
surfaces is smoothed with a rasp or file; then after careful inspection 
of the rings a line or band is marked where the measuring and dating 
will be done. For this purpose two parallel lines a half inch or more 
apart are put on, as nearly straight as possible. The space between 
these lines is then shaved with a sharp razor. This leaves a superb 
surface for measuring the rings. The lighting direction is important, 
but by a little practice the best position is readily found. The only 
special caution at this stage is that each break in the wood which 
has been glued should be marked and shaved along the crack so that 
dating and measuring can be carried past it without the slightest 
chance of error, but this rarely presents any difficulty. 

RADIAL STUDIES 

CIRCUIT UNIFORMITY 

By circuit uniformity is meant the close similarity of the ring 
records in all directions from the center of the tree. The funda- 
mental importance of this was fully recognized in the first formative 
period of this investigation. Cross-identification between different 
trees was first used as an essential in 1911, but this identity between 
different radii in the same tree was noticed in the very first trees 
measured in 1904. To describe where it has been found would be to 
enumerate almost every tree worked upon. Even groups that do not 
cross-identify well show circuit uniformity. This does not mean that 
the different radii are equal, but that the relative ring values are 
closely the same in all directions. So the present topic is for the pur- 
pose of calling attention to a few exceptions. Circuit uniformity 
is modified in three ways — by eccentricity, lobes, and gross-rings. 

Eccentricity — Slight eccentricity is very common. It becomes 
noticeable in perhaps one-third of the stumps examined and occurs in 
perhaps one-quarter to one-twentieth of the trees sampled. It merely 
means more growth on some one side than on the opposite. It is a 
common effect of group pressure and frequently occurs when two 
trees grow very close together. The maximum growth is then away 
from each other. It may be due to other causes. In the first 25 
Flagstaff yellow pines there was 12 per cent more growth to the north- 
east than in the opposite quadrant, attributed to better moisture con- 
servation in the shade of the tree. Eccentricity, unless excessive, need 
have no effect whatever on the tree record, and even if excessive it can 
usually be evaded. The most extraordinary case ever noted was a 



Carnegie Inst, of Wash. Pub. 289, Vol. II (Douglass) 





i V5u 

A. Forms of v-cut on stumps 




B. Complacent sequoia rings, D-8, grown in wet basin 




C. Sensitive sequoia rings, D-4, grown in uplands 









& §«r f '*? f?f Iff !P»«J 


__j£4? - •*» "* * 


* ,v ? •■ ' ■P2h-&m£& : ■-■■ 



D. Hyper-sensitive or erratic yellow pine rings, Pr. 62, grown near lowest 
yellow pine levels, Arizona 



RADIALS 23 

Scotch pine from Os, Norway, which had a 3-inch radius on one side 
and a 9-inch radius on the other. The maximum radius was used and 
it cross-identified in a perfectly satisfactory manner. Several of the 
trees from that locality showed a very rare characteristic in having 
the eccentricity change its direction as the tree grew older, due prob- 
ably to change in surrounding growth. This was less easily avoided. 
Forest Service men usually prefer a mean radius in eccentricities, but 
in this work it is not desirable, because in that kind of a radial the 
rings are apt to be inclined, making perpendicular measurement more 
difficult. 

Missing rings — In eccentricity the crowding in the shorter radius 
causes some rings to disappear altogether instead of merely becoming 
more minute. The same failure of rings is very apt to occur between 
lobes, especially in junipers. Hence in boring trees it is safer to choose 
the lobe itself than the depression between lobes. 

Lobes — In the case of lobes, or the scalloped outline of a tree-trunk, 
the variations observed in eccentricity are greatly exaggerated, in 
fact, so much so that trees like juniper and pinyon that go strongly 
to lobes can not well be used in ring studies. In an extreme, a given 
ring can not be traced from lobe to lobe. Such a tree of course has 
doubtful value. 

Pines and sequoias, however, have only a negligible lobe effect, 
except during the "infancy" period of the sequoias, when the lobes 
are very marked. They disappear in the early "youth" rings, which 
are really the earliest ones of any chronological value. When not 
pronounced, either the lobe itself or the depression between two lobes 
may be taken as the location of a radial, for the rings remain at right 
angles to its direction. 

Root influence — Lobes are usually more pronounced at the base 
of the trunk and show evident connection with the roots. Since the 
root supplies the sap which passes up the trunk and, in passing, forms 
the ring, the rings, it would seem, depend upon the way the sap spreads 
out around the tree as well as upon vertical movement. So in old 
trees whose rings are naturally crowded, we find some missing here 
and there in the circuit without much lobe effect being evident. In 
the general use of at least five trees in a group, such lapses practically 
always come to light. 

Gross-rings — A difficulty in the selection of radius in sequoias 
has been occasional radii where the rings are greatly enlarged. These 
are called "gross-rings." They are probably associated with the 
success of some certain root and therefore formed lobes or projecting 
curves about the trunk when the tree was growing at that size. Some- 
times these areas extend directly to a projecting curve of the stump 
outline and their relationship is evident. They not merely exaggerate 

3 



24 CLIMATIC CYCLES AND TREE-GROWTH 

immensely the average growth in certain parts of a radial line, but 
they do not hold to one radial direction and any straight line; cutting 
them at an angle has inclined rings, which therefore have an added 
fictitious size. 

Gross-rings only moderately represent climatic change. In an 
old study it was found that gross-rings in one tree corresponded to 
similar rings at that date in about half the other trees. They probably 
occur when for some reason the tree is having rather successful growth, 
and so they roughly indicate favorable conditions. It would probably 
improve the curve of the tree's growth if they were reduced to a size 
somewhat less than half-way between normal and their actual size. 
The inclination which they so often exhibit can be corrected by meas- 
uring in a different angle or by a multiplying factor. But either one 
adds greatly to the labor of handling large quantities of data in tables. 

Spiral gross-rings — A prehistoric section, H-9, from the Aztec 
ruins has a spiral of enlarged rings, which took about 12 years to make 
the circuit. It is impossible to tell from the specimen which way the 
enlargement rotated. The 9-foot Sitka spruce in the American 
Museum of Natural History shows at some 8 or 10 places about the 
circuit spiral enlargements with a very slow rotation. 

VERTICAL UNIFORMITY 

Outside tests — The close resemblance between ring records at 
different heights in the same tree was assured for the yellow pine a 
score of years ago, but has only recently been tested formally for the 
sequoia. During the trip of 1925, a windfall in the Springville region 
offered such a good opportunity for tests of this sort that it seemed 
worth while to take advantage of it. This tree, whose uniform trunk 
was about 15 feet in diameter, had been blown down in 1901, according 
to Mr. Elster, close to the houses at Enterprise, which had been started 
as a mill-site some three years before. The tree is lying there in excel- 
lent condition. The Swedish increment borer was used at 9, 15, 
and 35 feet from the base of the roots and thereafter at each 20 feet, 
to a distance of 235 feet from the base. At 255 feet small pieces were 
cut with a saw, in wood which had been a living branch and in a dead 
part which had been the main stem. This last showed nearly a 
thousand years in the radial and has not yet been identified, probably 
on account of the smallness of the rings. Yet 900 years in the living 
branch were readily dated, and at 20 feet below this point the cross- 
identification is perfect, though the branches begin nearly a hundred 
feet lower down. The lowest boring was well within the root system, 
close to ground-level, and does not identify well after 1700. With 
this exception, similarity in heartwood record, which extends to about 
1800, is striking at all heights above the ground. But the sapwood 
rings show profound differences, due it is thought (p. 101) to irregular 



RADIALS 



25 



swelling from the moisture which has filled them for years. Figure 1 
shows parts of the heartwood curves, from 1550 to 1590, including 
the year 1580, which is very distinctive when taken together with 
1548 and others. Figure 2 shows the variable sizes of sapwood rings, 
interfering greatly with dating and presenting a most unusual con- 
dition in the sequoia. 

The curious fact became evident that the tree grew in places a 
long time after falling, for most of the borings show a serious injury 
about 1901 and some show no growth after that. But some show 
continued growth up to 1915. This appears in figure 2. Evidently 
roots still in the ground supplied moisture and supported growth for 
more than a dozen years after the tree had fallen. 



115 



95 



75 



§ 55 

a 
I 

■S 35 



15 



VV\/ 


A 


C\A^ 


•Av 


A\ 




^V\/V 


J\ 






/Xa 


£ 


/\\/V 


V 




V 


V ^\ 




^|W- 


\/V 


A/vA/ 


N-^/v 


\ 




Ai\A- 


V 1 

A 


"WJ 


YVs^ 


^ 


a/ 


A*ft\ 


V 


'Vs 


A/f\ ; 


K A 


r 

A - 


V 


f\ 


w 




K 


& 










V | 















A /^. 






A / 


n A 


vy 


A / 


VsA 
^ 


/\jS 




j) 


La. 








V 




/W 


■^-A / 


vA 




Aa 


aA 


c 


^ 


V V 


w^ 


' vv 


£fc 


-aW 






<jy/ 




Sean 


vy V 

o/a ve/ 


i/cafsi 


ict Son/ 


iter/or 


r 

r/nsjs 



255 
235 

215 £ 

CD 
CD 

»-H 
►1 

o 

195 B 

a* 

S 

175* 
155 | 

135 



1530 40 1550 60 



80 1590 1530 40 1550 60 

YEARS 



60 1590 



Fig. 1 — Heartwood rings at different heights in the sequoia; total height 265 feet; vertical 
uniformity nearly perfect. Scale X 7.5; horizontal line with each curve represents 1 mm. 
growth 



Naturally, this matter of longitudinal or vertical uniformity was 
considered and tried out informally in the early work on this subject, 
and, so far as the eye could tell, the same rings existed at different 
heights. The fact that cross-identification applied equally at different 
heights in the trunk of the tree was held sufficient at the time. For 
example, D-18 and D-20 were each cut about 50 feet above ground- 
level, and yet they cross-identify and otherwise appear exactly as 
sections near the ground. The recent work of MacDougal and Shreve 
on the longitudinally bisected tree is adding to our knowledge, and it 



26 



CLIMATIC CYCLES AND TREE-GROWTH 



is desirable to see such studies applied to mature big trees and to 
yellow pines, each in its natural home. 

Central tests — A recent test at the center of a sequoia came about 
in this way. Stump numbered D-22, whose picture is shown in 
Volume I, Plate 7, A, was sampled in 1918. It had over 3,000 rings, 
but other innermost ones were missing on account of a large hole in the 
center. The earliest ring found was 1087 b. c. The estimated radial 
loss in wood at the center was 12 cm. (some 5 inches) or about 75 
rings (Volume I, p. 52, table 5). The "butt" log from this stump was 
lying not far away. In 1925, it appeared that in the upper end of this 



115 



95 



75 



55 



1 35 

I 







\jA 




l/V_ J. 






^J^ 


^f 


\rV ' 




*"A 


\, 




Av 


^ 


A 


\ 

ft A J 




r 




vw 


V 


y* 




/*\ 






'W 


~\A 


yv 




vy\ 






/Vv 






wA 

f 


J V 






(Af 






V 


v 






r v 




Vw 




\ 



























^M 


*\j 






V^ 








V 


l^V, 


f 

/ 


^^ 


/* 


r 


w^A. 


.1 












vA^s. 


/*v 




\f^ 


^V 






V^/ 






W\^ 


V 


u^ 




sTs/^ 


N7 ' 


r" 




i 







255 
235 

215 ? 

195 £ 

I 
o 

175 § 
155 

135 



1850 60 70 80 90 1900 10 20 1850 60 70 80 90 1900 10 20 

YEARS 
Fig. 2 — Sapwood rings in fallen sequoia; irregular growth after falling (in 1901) is shown with 
distortion due to water-soaked condition. Scale X 7.5; horizontal line with each curve 
represents 1 mm. growth 

log there was no hole and the rings originally filling the hole in the 
stump might be found and measured at this point. So a special cut 
was made crossing the center and extending a few hundred years 
along the best radius. This direction proved to be away from the 
original radius, but in the sequoias that practically never makes any 
difference. This cut was 12 feet above the original cut. It was hoped 
that the new piece would carry a record even beyond D-21, the oldest 
of all the sequoias. But this wish was not fulfilled, although this 
center v-cut proved very interesting. It cross-identified with perfect 
ease and entire certainty. The central growth was in 1115 B.C. So 
only 30 years were gained, but it thus carried a record back very nearly 
as far as D-23 nearby, whose innermost complete ring was 1122 b. c. 



Carnegie Inst, of Wash. Pub. 289, Vol. II (Douglass) 



** 




A. Fallen sequoia, Enterprise, on which vertical uniformity tests 
were made 




B. Sequoia "California," Enterprise; and Mr. C. A. Elster 



RADIALS 27 

At the same visit in 1925, it was remembered that D-23, whose 
earliest ring has just been given, also had a large hole in the center, 
with an estimated loss of 14 cm. or 80 years. This D-23 or Centennial 
stump, has a large fragment lying near it on the ground, but a search 
showed that only some outside pieces were there and the central 
parts were entirely missing. Thus, there is no chance of extending 
the record of D-23. In this connection it may be added that the 
oldest tree, D-21, whose earliest complete ring is 1305 b. c, has only 
an inch missing at the center, perhaps a half-dozen years, and so there 
is no chance of material extension of that record. The central part of 
that stump is carefully preserved and mounted in the laboratory.* It is 
shown in Plate 1. 

A tree known at Springville as "California" and numbered D-47 
in my series was cut years ago for the purpose of building a sequoia 
hut. It stood isolated, about half a mile from the Centennial stump 
in a southerly direction. The stump has a very high, projecting 
center, with steep ax-cut slope to north and a walk-way all around 
where slabs of wood were removed. The top and nearly all the trunk 
He off to the east, with a smooth sawed face 15 feet in diameter, as 
shown in Plate 4. My v-cut was made on this face, extending past 
the center. Almost at the last moment of my visit one of Hunting- 
ton 's grooves (but no number) was found on this stump, showing that 
he had counted the rings. So for comparison we made a short central 
v-cut. This was about 12 feet above the ground and also about 
12 feet below the full radial taken from the log. This will be studied 
in connection with ancient records. 

♦The smallness of this hole where the infancy rings used to be, suggests that this cutting- 
level was 20 or 30 feet high on the tree when it was a sapling. If so, the ground about this tree 
has filled rather than eroded. The adjacent contours make this possible. 



IV. RINGS 

During and following the processes of cross-identification and 
dating, described in the previous volume, the best ring records are 
picked out by a form of selection, first between the different trees of 
the group, and second between different parts of each tree record. 

SELECTION IN GROUP 

During cross-identification it is very easy to see which specimens 
conform best to the group type and which ones conform so little as to 
be discordant, for in all the groups used a group type is evident. It 
becomes, then, easy to recognize any specimen which for some reason 
or other, perhaps a fire injury or a different water-supply, does not 
agree with its group. Such specimens are obviously so far from the 
average that probable errors are diminished by their omission and 
their values are not included in the group average. Such individuals 
are usually very few in number, in the majority of groups none at all, 
and they include of course the ones which can not be cross-identified. 

MEAN CONFORMITY 

In judging whether any tree should be retained in the group a 
criterion called "mean conformity" has been very extensively used. 
It is the agreement which any individual shows to its group or type. 
In effect, it is an added weight given to individual specimens which 
have the best support from other members of the group. 

Quantitative conformity — An actual numerical value of this con- 
formity could be derived by mathematics (by mean residuals from 
group averages), but it would be a long process and the results at the 
present stage would not be worth the labor; for after familiarity is 
reached a conformity coefficient can be estimated, as in a multitude 
of different scientific observations. However, in connection with the 
selection of best sequoia records for comparison with Arizona pines, 
a quantitative value was reached in a practical way. The Arizona 
variations were kept fresh in mind as each sequoia record was reviewed. 
The number of Arizona features found in each sequoia for each of the 
last five centuries was carefully recorded and the total placed against 
each sequoia as its weight or conformity. Those having the best con- 
formity were then selected for certain comparison problems. This is a 
good practical method. Other selections have not been made on so 
large a scale and did not need such formal organization, but nearly all 
have been based on some modification of this process. 

Weighted means — After mean conformity of each member of a 
group has been obtained, it may be used simply to exclude poor 
28 



RINGS 



29 



records, so that the average of the remainder will be improved. If 
some approach is made to a numerical value of this conformity, then 
it may be used to obtain a weighted mean. This was done in the case 
of the four best sequoias selected for dating comparisons with Arizona. 
This was a long process, but its application did not make enough 
difference for one to feel that its universal use is necessary. 



MEAN SENSITIVITY 

Another criterion which helps in selecting the best record has 
come into practical and important use, even though the computation 
of numerical values is a refinement not usually applied. It is called 
mean sensitivity (see also p. 104) and is an inherent character in each 
individual. It may be denned as 



Moist 
upland 



Dry 
limate 



V ' s 


' D8 


JU/ 


\(\a 


V V 


D4 


ifi r 


A 


Ifw 


PR.62 



mm. 
1.00 



0.11 



1.00 0.33 



1.00 0.64 



the difference between each two 

successive rings divided by their 

mean. The quotients are arranged 

in groups of 10 or some other 

number of years, and listed as the 

mean sensitivity of that period. 

Plate 3 shows the appearance of 

rings of different sensitivity. The 

first section (B) came from a 

sequoia which grew in a swampy 

basin about 15 miles east of the 

General Grant National Park. 

The tree had a "complacent" 

growth, with all rings of nearly 

the same size. Its mean sensitivity 

is 0.11. The second is a sensitive 

sequoia which grew near the top 

of the mountain, 800 feet higher 

up, with a limited water-supply and therefore more dependent on 

the moisture of each year as it came. Its rings have more character 

and individuality, and the changes from ring to ring are much more 

evident. The mean sensitivity is 0.33. The third is a hypersensitive 

dry-climate yellow pine near Prescott, one of the 10 used in the curves 

of Prescott tree-growth already described. It grew near the lowest 

limit of the yellow pine. Some of its rings, such as 1841 and 1857, 

are so small as to be found with difficulty. Its variations from year to 

year are extremely large, and its mean sensitivity is 0.64. 

The way these variations in sensitiveness look in plotted curves 
is shown in figure 3, in which the curves of growth of these three trees 
show percentage departures, each from its own mean. The different 
character resulting from the different environment is at once apparent 
to the eye. 



1840 1850 I860 

Three types of sensitivity 

Fig. 3 — Mean sensitivity and soil moisture 



30 CLIMATIC CYCLES AND TREE-GROWTH 

Practical application — The practical method of handling mean 
sensitivity is to take the sum of all the changes in 10 years without 
regard to sign and divide by the sum of the 10 years' growth. This is 
the way it has been used in the limited mathematical tests. As a 
matter of fact, high sensitivity in a ring sequence is often apparent 
to the eye, as anyone can see in the illustrations, and in much exploring 
work the eye estimates have been the practical and rapid way for 
using this criterion in judging between ring records. 

SELECTION WITHIN RECORD 

The recognition of the preferable parts of a sequence of rings comes 
from an understanding of the natural divisions of a tree's ring system 
due to age and the recognition of the various kinds of errors and 
difficulties in the rings themselves. Most important of all perhaps is a 
knowledge of the meaning of rings in terms of their environment. 
This last part of the subject is discussed in Chapter VIII. 

PARTS OF A TREES RECORD 

All parts of a tree 's record are not equally useful. For purposes of 
description a good record may roughly be divided into infancy, youth, 
maturity, and age. These are largely recognized by the size and 
character of the rings. 

Infancy rings — These are most easily found in the sequoia and 
consist of a central series of extraordinarily large rings, sometimes 
2 cm. in width, 10 to 50 in number, showing practically no variation 
except a successively diminishing size. They are very soft and in very 
old trees often disappear, leaving a conical hole extending to some 
height from the ground up into the tree. This is probably the explana- 
tion of the rather common central hole, sometimes untouched by fire, 
as shown by study of stumps. This was formerly attributed to other 
causes, but some recent identification of the central parts of very old 
trees described above under "Vertical uniformity" have favored this 
view. 

Youth — The youth of a tree is evidenced by large complacent 
rings, usually largest in the center and outwardly growing regularly 
smaller. Speaking from an economic point of view, the tree at this 
time has to build a large trunk in order to support the growing top 
and resist wind. It is true, as Antevs pointed out, that at this stage 
the tree shows large, less sensitive rings. In the yellow pine this 
period is likely to be 20 to 40 years, but even in these immature rings 
in many trees cross-identification is perfect almost to the center. 
This is not always so, and often it is best to drop the inner 20 rings. 

The youth rings of the sequoia cover perhaps 300 to 800 years. 
It is the region where the rings are large and show a gradual diminu- 



RINGS 31 

tion. Cross-identity carries through it usually with perfect ease. It 
is not always easy to recognize the end of this period. In rare cases a 
tree gets down to small growth in 200 years. It is possible that tests 
of mean sensitivity would provide a means of judging. In addition, 
actual climatic change enters here as a variable. A considerable 
number of the dated trees started near 300 b. c. and show the reduc- 
tion in ring-size near 400 to 600 a. d. It is probable that there was a 
climatic drying at about that time which helped these trees to reduce 
ring-growth. 

Maturity and age — Maturity in pines and sequoias covers the 
time from the attainment of full height to the decay at the top which 
indicates old age. During this period the rings have their best sensi- 
tiveness, though almost equal sensitiveness may last into old age, when 
the rings become smaller and possibly a trifle less sensitive and yet a 
trace more erratic. That is, there are longer periods with little varia- 
tion, broken by a little more frequent complete disappearance of a 
ring from the sample under study. The growth has gone to some 
other part of the circumference. These are the unusual cases. It has 
never seemed desirable to discard the outer parts of a tree so long as 
the rings were certainly identified. 

RING ERRORS 

Superfluous rings — The one fundamental quality which makes tree 
rings of value in the study of climate is their yearly identity. This is 
sometimes disturbed by the presence of too many or too few rings. 
Superfluous rings are due to doubling. This is a climatic phenomenon 
to which some trees are especially liable, probably from their location 
and rapid growth. But let us keep clearly in mind that superfluous 
ring formation is the exception. Out of 75 trees collected near 
Prescott, only 4 or 5 were discarded for this reason. Out of hundreds 
near Flagstaff, none have been discarded on this account. 

Nearly 200 yellow pines and spruces from northwestern New Mexico 
have produced no single case of this difficulty. The sequoias from 
California, the Douglas firs from Oregon, the hemlocks from Vermont, 
and the Scotch pines from north Europe give no sign of it. On the 
other hand, 10 out of 16 yellow pines from the lower levels of the 
Santa Rita Mountains south of Tucson have had to be discarded, and 
the junipers of northern Arizona have so many suspicious rings that 
it is almost impossible to work with them. Cypress trees also give 
much trouble. Trees whose extra rings can not be exactly identified 
are always excluded in part or as a whole. 

Missing rings — The other difficulty connected with yearly identity 
is the omission of rings. Missing rings occur in many trees without 
lessening the value of the tree, unless there are extensive intervals 



32 CLIMATIC CYCLES AND TREE-GROWTH 

over which the absence produces uncertainty. A missing ring here 
and there can be located with perfect exactness and causes no uncer- 
tainty of dating. In fact, so many missing rings have been found after 
careful search that they often increase the feeling of certainty in the 
dating of rings. 

Missing rings occur when autumn rings merge together in the 
absence of any spring growth. This rarely, if ever, occurs about the 
entire circumference of the tree. There are a few cases in which, if 
the expression may be excused, I have traced a missing ring entirely 
around a tree without finding it. I have observed many cases in which 
the missing ring has been evident in less than 10 per cent of the circum- 
ference. Some are absent in only a small part of their circuit. I have 
observed change in this respect at different heights in the tree, but 
have not followed that line of study further. It can be studied in the 
longitudinally bisected tree. A missing ring is often represented by a 
slight enlargement of the red autumn ring of the previous year. 

One sees from this discussion what the probable errors may be in 
mere counting of rings. In the first work on the yellow pines, the 
dating was done by simple counting. Accurate dating in the same 
trees (19 of them) later showed that the average error in counting 
through the last 200 years was 4 per cent, due practically always to 
missing rings. A comparison in 7 sequoias between very careful 
counting on the stump and accurate dating in 2,000 years shows an 
average counting error of 35 years, which is only 1.7 per cent (Volume 
I, pp. 15 and 45). 

Simulated doubles — In the process of counting and dating rings 
in Arizona pines, two sharp red rings sometimes occur close together, 
giving the appearance of a double and leaving one in doubt as to 
whether one year or two is involved. In such cases the following 
probabilities apply: If the tree has other obvious doubles, the case 
in hand is likely but not certain to be another doubling. If the two 
red rings are unequal in size and the smaller one is inside, that is, 
nearer the center, it is likely to be a real double formed by the spring 
drought. If the smaller one is outside the larger, it is probably a 
separate year. If the two rings are equal and either one shows a 
further doubling, the two rings in question are separate years. If 
the case is still doubtful, cross-identification may settle it. But if 
that fails, the doubtful part should be discarded. The most tantalizing 
case of this kind that I have is an early historic beam from Pecos, 
KL-I, in which all kinds of doubles are exhibited. 

Reinforced rings — Certain groups of prehistoric specimens from 
the Wupatki National Monument, northeast of Flagstaff, show heavy 
reinforcement in the youth rings of many trees. That consists of 
very hard tissue formed during the rapid spring growth, so that each 



RINGS 33 

ring is greatly expanded in one direction and somewhat diminished 
on the opposite side. This gives the appearance of a series of cres- 
cents on one side of the tree section. It usually interferes completely 
with the rain record in the tree, but at the same time has a strong 
climatic significance as an indicator of heavy spring winds. 

Other false rings — Other abnormal rings are sometimes produced. 
Sequoia radials occasionally show certain "pitch" or "pith" rings. 
These are white, very narrow, and totally different in color from the 
rest of the wood. If they seem very soft, they have been noted as 
pith rings; if hard, as pitch rings. They may come either within a 
year's growth or between two years. They therefore are very annoy- 
ing, for they destroy the count, it being impossible to tell whether the 
normal rings on each side belong to one year or to two. I have made 
it a rule to discard entirely regions of ring record thrown into doubt 
by such rings. Doubtless they come from injury and usually from 
fires. In the yellow pines no similar rings have been noted, but in 
each tree abnormally large rings occur close to large fire injuries during 
the early period of recovery and diminished rings in other parts of 
the tree circuit. 

Effect on means — In all cases of ring errors that leave any uncer- 
tainty in dating, the uncertain part, or even the whole tree, is omitted 
from the means. In large groups, of course, the omission of a tree is 
usually a small matter, but in the early years of the group record it 
may be serious, for the number of individuals decreases as we go back 
to earlier and earlier dates. In such cases only the uncertain part 
is omitted. But here another difficulty is introduced, namely, the 
break in the averages at the beginning and end of the omitted part. If 
the tree in question agrees very closely with the mean of the rest in 
size of rings, the break does not introduce error; but if it is very 
different, it has to be merged with the average of the rest in some way. 
This becomes the same problem as that of introducing a tree of late 
starting-date into a long group record. 



V. INSTRUMENTS AND TECHNIQUE 

In dealing with the 175,000 growth-rings, dated, measured, and 
used in these volumes, special tools have been adopted or developed 
at every stage of the process to secure material and to hasten and 
improve results. 

COLLECTING TOOLS 

Saws — The articles needed in field trips include a chisel for marking 
numbers, paper and cloth bags for holding fragments cut from individ- 
ual trees, a recording notebook, marking crayon, a shoulder-bag, 
camera, and various saws and borers. The best handsaw is known 
as a flooring saw, in which the teeth are on a curved edge of steel, 
as shown in Plate 2, A. With this, one can make a v-cut in the middle 
of a stump without touching the edge at all, or the saw can cut in from 
one side to the center without touching the other half. In working 
without help this has saved many hours of labor and energy. The 
convenient size of saw has a blade about 20 inches long. A 3-foot 
cross-cut saw used by lumbermen does at times prove very useful, 
but its extra weight and awkwardness in packing have always been 
against it. 

Swedish increment borer — Since 1920 the Swedish increment borer 
has been used extensively to get records from living trees. It is very 
successful in softwoods such as pine and fir. Hardwoods and juniper 
are too tough for penetration without great danger of breaking the 
instrument. The cores obtained are very slender, smaller than a pencil, 
and reach to slight depth in large trees, but the method of mounting 
has been raised to such a degree of efficiency and the collection of 
material becomes so rapid that the deficient length and occasional 
worthless specimens are counterbalanced. In most regions the incre- 
ment-borer material can be supplemented by a few cuts from stumps 
carrying the tree record back into the past as far as the forest permits. 
Thus the borer supplies the contemporary record, that is, the last 100 
years or so from many trees, and the saw supplies the historic record 
going back for centuries. 

In countries where native timber has been cut off and the yearly 
"crop" of lumber comes from planted and reforested areas, it is very 
important to know how growth is progressing. So Swedish ingenuity 
produced this tool for sampling the outer rings of a tree. The borer 
is a tube of 4 to 5 mm. inside diameter (i to i inch) with a sharp 
cutting-edge and prominent spiral threads to draw the tool into the 
tree by twisting, as with an auger. Near the cutting-edge is the largest 
outside diameter of the tube, about half an inch. A tubular cross- 

34 



INSTRUMENTS AND TECHNIQUE 35 

piece handle, which at the same time serves as carrying-case for the 
cutting-tube, gives a strong purchase in turning the borer. When the 
tree is bored as far as desired or practicable, a long, fine wedge is 
thrust into the cutting-tube from the open end outside to hold the 
core tightly in the cutting-tube while the borer is screwed out from 
the tree. The first turn, of course, breaks the core away from the 
tree and the core may be pulled out intact by the wedge. A difficulty 
with this tool is the fact that in soft and watersoaked wood the outer 
and softer layers are sometimes compressed and twisted. This is 
usually negligible, but on one occasion in a dead sequoia the water- 
soaked wood wedged in the borer so firmly that it had to be removed 
by boring another tree and thus pushing out the wedged fragments 
(boring in fallen sequoia at 215 feet from base of root, shown in part 
in figs. 1 and 2). 

Core mounting — The cores usually come out intact, but gluing 
pieces together is so satisfactory that breakage is no drawback. The 
core is at once numbered in pencil every inch or two of its length, so 
that its pieces may be identified if it breaks. It is then put in a paper 
bag long enough to hold it and a full record made on the outside of the 
bag. Other numbered cores and their records are added in the same 
bag, as they help to keep each other from breaking. 

These cores are mounted on half-round strips of wood 12 inches 
long and f inch wide. A shallow saw-cut is made lengthwise at the 
rounded top, and this cut is rounded with a small round file so that the 
core will he snugly in it. It is then glued with the bark end to the 
right and about 1 inch from the end of the mount. The number is 
placed at once on the mount at that end. In gluing, the vertical grain 
of the tree is turned over into a horizontal position. This gives a 
chance for just the right stroke with the razor blade in "shaving" the 
surface so that the rings are brought out into the greatest prominence. 
Identification and dating notes are placed on the wooden mount. 
The various groups of these mounted specimens are tied in bundles and 
filed in drawers of the proper width and depth. Such samples resist 
very rough handling, last indefinitely in this form, and are always 
ready for further study. 

Mr. Duncan Dunning, of the Forest Service office at San Francisco, 
has made a temporary clamp of great convenience, in which the core 
may be held while measures of its rings are made. Considering the 
vast number of cores used by the Forest Service and the ease of 
replacing lost or injured specimens, this temporary mounting is 
extremely valuable. 

Borer extension — The 12-inch borer is the one commonly used, 
giving a practical 10-inch core. A 10-inch borer was first tried and a 
14-inch has been under examination, but seems too heavy. Very long 



36 CLIMATIC CYCLES AND TREE-GROWTH 

borers for greater depth in the tree will probably have to be made in 
single pieces of tubing. 

The tubular borer — This borer was designed especially for the 
dried and sometimes very hard logs in the prehistoric ruins. It will 
work on pine trees and junipers. It gives a core 1 inch in diameter, 
which means a better chance of finding obscure rings than in the 
increment-borer cores. The borer is a 1-inch steel tube with small 
sawteeth at one end and a projection at the other for insertion in a 
common brace. Collections to date include some 30 or 40 very valuable 
cores made with this instrument. In actual operation the core has 
been broken off and drawn out about every 3 inches in order to help 
get rid of sawdust. This extraction is done by a i-inch steel rod 
with a wedge at one end for breaking the core off and a screw at the 
other end to catch the core fragment and draw it out. 

There are two chief problems with a borer of this sort — sawdust 
and the labor in pressing the borer into the tree or log. For the former 
a 1-inch auger hole carried below the borer hole and a little in 
advance has been used advantageously, but frequent breaking of the 
core is more certain. For the latter a chain-drill attachment was tried 
unsuccessfully, as it cracked the borer. An auger guide for limited 
depths is working extremely well in some cases. This guide is a hollow 
cylinder 4 inches long and 2 inches diameter, with thick walls. Length- 
wise down these walls i-inch holes are placed fairly close to each 
other. This guide is screwed to the tree or log with the guide-holes 
pointing toward the center of the tree. Then a small auger bores into 
the tree through the holes in succession. The guide is then removed 
and the tubular borer quickly frees the core. In this arrangement 
the auger holes take care of the sawdust and the auger itself needs no 
pressure for forcing it into the wood. The core is not so presentable 
in appearance, but is easily rounded to a desirable form. This makes 
a very good form for use on prehistoric beams, but does not solve the 
problem of deep boring in living trees. A device using the principle 
of the chain-drill attachment is now under test. There is no doubt 
that a suitable depth borer can be developed. An effective length of 
28 or 30 inches would be enough for the yellow pines. A borer to go 
12 feet into big sequoias would probably have to be designed for use 
with an engine or motor. One would have to be sure beforehand that 
living trees would supply data worth the trouble. 

Injury to living trees — It has been an invariable custom to plug 
the holes made in living trees so as to keep out any possible infection. 
This is easily done with a small branch from the same tree, cutting 
the bark entirely away, so that only healthy sapwood goes into the 
hole. This amounts to grafting a young branch onto the trunk. Even 
without this precaution it is not probable that any harm results, as the 
holes quickly fill with sap or pitch. 



INSTRUMENTS AND TECHNIQUE 37 

Razor-blade holder — In giving a final superb finish to the wood 
surface, nothing has been found to replace the razor-blade. Files, 
emery cloth, and scrapers always leave the edges of the wood cells in 
a ragged state. This may be overcome to some extent with kerosene, 
oil, or furniture polish, but after clean cutting with a sharp razor-blade 
the oil finish is far superior. Also, in decayed or burnt wood, after 
treatment with paraffin, the razor leaves a surface which will permit 
adequate magnification. Different forms of mounts could easily be 
made, but a round steel handle split down an inch with a hack-saw 
and a good screw to draw the split ends together serves as a very 
convenient mount for the safety-razor blade. 

Paraffin treatment — Soft or mealy wood or charcoal is rendered 
workable by a treatment with paraffin dissolved in gasoline or benzine. 
This solution should be applied copiously, so that it may enter deeply 
before it dries. Putting the whole specimen into a jar containing the 
solution has been found very satisfactory where practicable. Boiling a 
frail specimen in paraffin is an excellent method of preservation to 
apply while out in the field. 

MEASURING INSTRUMENTS 
EARLY FORMS 

Ruler — As would be expected, the first measures were made by 
readings from a steel ruler on edge against the wood. These measures 
were all made by the writer and were subject to the errors of estimating 
tenths of a millimeter, but in coarse rings such errors play very little 
part. 

Cathetometer method — This method was worked out for the very 
long sequoia records and is still regarded as the standard method. 
It was described in Volume I and need not be repeated here. 

PLOTTING MICROMETER 

It seemed possible to save a large amount of time by some method 
of plotting direct from the wood and a special instrument has been 
designed and constructed for the purpose. 

General plan — In general plan the instrument has a fairly inexpen- 
sive screw, 6 inches long by about 1 cm. in diameter, with threads 
having a pitch of 1 mm. A knurled head and a graduated head are 
attached at the right end for turning and for special reading if desired, 
but the graduations have not been used (see Plate 5) . 

The nut on this screw, by a single point of contact, moves a carriage 
supported on a separate track. The carriage has two upright pieces, 
between which a small telescope swings on a horizontal longitudinal 
axis. The left end of the main screw opposite the graduated head has a 
knurled head which is removable. Below this head, but not in contact, 



38 CLIMATIC CYCLES AND TREE-GROWTH 

is a similar head, also removable. The latter is attached to a small 
drum with spiral thread about it, in which works a catgut string. 
Between these two knurled heads, but not touching them, is an alumi- 
num disk on the end of an arm, so made that by pressure on a lever 
the disk comes into contact with both these knurled heads and thus 
transmits the motion from one to the other and so from the main screw 
to the catgut string. Several pairs of these knurled heads of different 
relative sizes are supplied, so that motion in the catgut will be 20, 40, 
or 100 times the motion of the carriage and telescope. By this means 
change may be made in the vertical scale of the plot. 

Below the main screw and parallel to it is the plotting cylinder. 
This is so arranged that the same lever-arm that brings contact between 
the knurled heads moves this cylinder 2 mm. in rotation, measured 
on the surface of the record paper. The ends of the catgut string pass 
over rollers and extend parallel to the recording cylinder, and after 
one end turns back on a small wheel the two ends meet and are attached 
to the pen carriage, which travels on its own track parallel to the 
recording cylinder. Thus, when the lever-arm is pressed and the 
micrometer screw moves the telescope thread across a ring, from one 
sharp outer edge to the next, the pen draws a line in proportion trans- 
versely on the record sheet. The release of the lever-arm at the left 
moves the cylinder, and the pen is restored to zero position. Thus a 
columnar plot, here called "auto-plot", is made by setting on one ring 
after another. 

Accuracy — The rapidity and mechanical accuracy of this instru- 
ment are high. The graduations of a steel ruler were measured with 
a very small percentage of error; that is, the accuracy is greater than 
the accuracy of setting on a ring. 

Advantages — The instrument saves much time, because it makes 
automatically the plotted records which in the cathetometer method 
were plotted from the readings: These automatic records are called 
auto-plots. The distance of the wood from the telescope does not 
have to be fixed. In fact, I have measured rings in wood lying in 
glass cases by placing the instrument on the outside of the case. 
The records are in a convenient form and may be very long. They are 
made on coordinate paper to definite scale, so that values may be 
read off from the plots for use in tabulation. The plot is also ready 
at once for a standardizing line, such as will be discussed below. 

Disadvantages — While the rapidity and accuracy of this method 
exceed any other, its disadvantage lies in the difficulty of checking and 
correcting the work after it is done. Coarse rings are readily handled 
by inexperienced helpers, but the fine ones under 0.5 millimeter are 
subject to mistakes. This is usually a question of identification, but 
the difficulty in checking work immediately after it is done (without 



Carnegie Inst, of Wash. Pub. 289, Vol. II (Douglass) 




<}? 



A. Plotting micrometer 




B. Longitudinal plotter 















\ff\ 


l^^ll ' > ilM 



C. White cyclograph 



INSTRUMENTS AND TECHNIQUE 39 

doing it completely a second time) is great, and so these errors of 
identity are not discovered until a careful revision is made by the 
writer. All this refers, of course, to the measurement of records care- 
fully dated beforehand. 

Measuring directions — The best plan for preventing errors in 
measuring is a written set of measuring directions, telling where to 
begin and end, what rings, if any, to omit, which are small or micro- 
scopic or absent, and where dangerous doubles occur. When a radial 
sample is specially illuminated during measuring in order to see the 
rings well in a telescope, marks and directions on the sample may 
easily be overlooked, but a separate list on a paper at the side can be 
followed with greater success. 

Other applications — Extensive experience with the ordinary filar 
micrometer in astronomical work led to a design of this instrument 
which could be used on a telescope for the repeated measurement of 
the same distance, such as planetary diameters, separation of double 
stars, and so forth. The box of the plotter was arranged to receive 
on one side a bushing adapted to the slide-tube of a big telescope and 
on the other a positive eyepiece. Close to the eyepiece is a plate 
carrying a stationary thread, while another plate attached to the 
carriage has the movable thread. The latter is first placed on the 
left side of the planetary disk and the stationary thread on the right. 
Then the lever-arm above described is pressed and the movable thread 
carried to the right until it reaches the right edge of the disk when 
the other is at the left edge. Thus the double diameter is measured. 
This may be repeated as many times as desired before looking at the 
record. A thread stretched along the tops of the columns will give the 
mean value. This same method can be used in the measurement of 
average seed diameters under the microscope or the sizes of grains of 
sand or other objects under special study. 

LONGITUDINAL PLOTTER 

The measuring instruments so far described all require accurate 
dating beforehand, for corrections are hard to enter after the ordinary 
transverse plot has once been made. It happened that considerable 
material came to the laboratory with groups of very small rings 
which I did not have time to date, but at a time when there was 
available the help of an assistant. It was therefore desirable for him 
to put on a ring-count and make measures which I could correct at 
my leisure. This was accomplished by the longitudinal plotter (Plate 
5, B). It simply reproduces the spacings which exist on the wood on a 
large scale that can be varied to suit the needs of the rings. It repro- 
duces very rapidly and two independent records are placed side by side 
on the long paper tape such as is used in adding machines. This is 
called the longitudinal plot, or more briefly, the "long-plot." The 

4 



40 CLIMATIC CYCLES AND TREE-GROWTH 

instrument consists simply of a slow-moving carriage on which lies 
the wood sample and a fast-moving drum upon which hangs the record- 
ing tape. These are connected by gearing which normally permits the 
surface of the drum to move 12 times as fast as the carriage. A pair of 
gears may be removed and another pair substituted, giving different 
ratios, so that the range of magnification is from about 4 to about 34 
times. In this way a convenient size is entered on the recording tape 
and the record becomes partially standardized. The motion of the 
carriage and specimen is watched through a small stationary telescope 
placed a few inches above and f ocussed upon the rings and the motion 
of the drum is recorded on the tape by a pencil line drawn across it 
against a fixed wire. 

Accuracy — On the whole, an inexperienced assistant can handle 
this plotter better than any other form of measuring instrument. 
The duplicate records side by side check each other nicely. It is still 
subject to errors of identification, but a large quantity of dated speci- 
mens have gone through this process with good success. It is doubtful 
if the settings have been quite as accurate as in the auto-plot, but they 
are still as good as the sharpness of the rings permits. 

Graph and table — A sheet of coordinate paper is marked with dates 
and then each ordinate is entered simply as the sum of the lengths 
of that year in the two adjacent longitudinal plots. This gives an 
ordinary graph on which a standardizing fine may be drawn, as 
described below. Suitable ring values for entering in a group table 
are then read off directly from the graph. 

CLERICAL OPERATIONS 

STANDARDIZING 

Need of equalizing trees — The groups of trees used in this study 
represent different regions. Therefore, the individuals of each group 
were selected to represent a considerable area rather than a localized 
spot. Hence the individuals differ in rate of growth. What we want 
in an average of a group is the common character which has come from 
climatic variation. In the tables in Volume I a simple average was 
used, as that was the easiest process and commonly used in scientific 
reports. But it is perfectly evident that a straight average does not 
represent an average of the common character, because in ordinary 
averaging the big rings in quick-growing trees dominate and variations 
in the slow-growing trees are practically lost. Logarithmic averaging 
has been considered; for example, multiplying the values from the 
different trees together and extracting the root corresponding to the 
number of trees used. But that is a long and expensive process, and 
it renders serious the occasional microscopic or omitted ring in very 
slow growing trees. The effect in such cases would be greatly over- 



INSTRUMENTS AND TECHNIQUE 41 

done. So the practical method of standardizing or equalizing trees, 
which has been used extensively for actual curve production (commonly 
modified as in the next paragraph), is to divide individual values by 
the mean value of the tree, so that the annual values of each tree will 
enter the group table as percentage departures from its own mean. 
Simple averages are then taken for each year in the group. This 
avoids some of the exaggerated effect of extreme departures. It 
places all the trees on an equality, but does not place all departures on 
an equality. It is averaging by weight, in which the weight is inversely 
proportional to the mean growth of the tree. 

Age correction — Young trees have to develop the trunk rapidly 
in order to stand the strain of wind and snow. Hence the early rings 
are larger and somewhat less sensitive to climatic effects. When the 
tree curve is plotted, it usually rises at the early end, sometimes very 
rapidly. A reduction to percentage departures does not correct this. 
One can correct it by getting percentage departures from a type curve 
developed mathematically, as Huntington did (1914), but it can be 
done far more rapidly and with sufficient accuracy by drawing a curved 
or broken standardizing line on the individual plot and getting the 
percentage departures from this line. Such a line is usually straight 
and horizontal for a large part of the record and slants upward at the 
early end. A curve is more accurate than a broken fine, but there is 
little real difference and the broken line is more easily described if it is 
necessary to state its position in words. 

Other corrections — Huntington used a " flaring" correction for the 
increased measured width of outer rings near the base of the big trees, 
where the spread of the root system is felt and a horizontal measure- 
ment is not perpendicular to the rings. Evidently, in drawing a 
standardizing line this can be taken care of. It is evident that in 
studies of cycles not exceeding half a century or so in length the flaring 
effect is negligible. But in estimates of very long periods or of secular 
values, this effect must be nicely gauged. 

It is much the same with his " longevity" effect. This effect simply 
recognizes that a slow-growing tree has a different normal age-curve 
from a quick-growing tree. The slow grower more quickly reaches 
the normal slow growth. This, too, is important in getting early abso- 
lute ring values, but plays little part in studies of periodic variation. 

Comment on standardizing — It is felt that standardizing serves 
two purposes: first, correction for age, injury and flare, and second, it 
compensates for few numbers in a group, so that 5 or 10 trees will give 
practically the same results as 25 or 100. It is not thought important 
to use it if the number of trees used in a group average is over 15 and 
the age variations are small. 



42 CLIMATIC CYCLES AND TREE-GROWTH 

Averaging — The sums are usually made on an adding machine 
and the divisions by slide-rule. Once or twice an average by weight 
has been made. If some character is recognized that makes the record 
in one tree better than that in another, a suitable weight can be 
included in the standardizing process by placing the standardizing 
line at a different ordinate. In the table the same effect has been 
produced by repeating the same tree in two or more lines, giving it 
double or more weight. 

CYCLE PLOTS 

Uses of tree-growth curves — There are three main purposes in 
producing tree-record curves and certain advantageous characters 
vary in these uses. They follow. 

Cross-identification — Curves for this purpose must display certain 
special characters like single small rings or drought groups of small 
rings, which from their extreme and unusual character are likely to 
extend over a considerable district. The single small deficient ring 
is the best characteristic to use in dating. Good years seem to spread 
their effects over a longer period of time and are not definite. 

Skeleton plot — In consequence, a special "skeleton" curve has 
sometimes been successfully used in cross-dating. Such curve is a 
long, narrow strip of coordinate paper, dated or numbered as usual 
and showing only the dates of very small microscopic or absent rings, 
which are indicated by vertical lines whose conspicuousness is propor- 
tional to the deficiency of the rings. No other rings are represented in 
these plots. Two of these skeleton curves from different trees, one 
known and the other unknown as to date, can be moved slowly past 
each other until similarity of spacing discloses identity in dates. 

Plotting climatic curves — By comparison of growth-curves the 
climatic origin of many tree variations is established; hence these 
curves need to show all the individual years. The scale should not 
be too great, as then it is difficult to compare two plots. Therefore, 
the ordinary form, consisting of points connected by straight lines, 
made on such a scale that slopes dominate, is the more convenient. 
It has been found most advantageous to use coordinate paper whose 
smallest divisions are 2 mm. and whose major fines are spaced at 5 
(not 10) of these small divisions. On this paper the smallest horizontal 
division commonly represents one year and rather commonly 2 vertical 
centimeters represent 1 mm. of tree-growth. 

Cycle plots — These are the curves arranged specially for studying 
the cycles. At first it was thought that the usual unsmoothed plots 
just described were well adapted for this purpose, but it was noticed 
that in searching out some cycle with the periodograph, or cyclograph 
as it will usually be called in this volume, several possible settings 



INSTRUMENTS AND TECHNIQUE 43 

were obtained differing by exactly one year, such as 17.1, 18.1, and 
19.1 years. This, of course, arose from retaining annual points in 
the plot and in the cycle one was apt to select some multiple of unity, 
that is, simply a whole number or very close to it, instead of an actual 
fractional value. 

Smoothing — Accordingly, some form of smoothing is now always 
used, and the Bloxam formula, which I have sometimes called Hann's 
formula, is generally accepted. But there are several variations of 
this process. 

Numerical Harm — The first is the simple application of the Hann 
or Bloxam formula, in which three successive (overlapping) values are 
merged into a substitute for the middle one by averaging the three, 
with double weight given to the second. It is this double weight 
applied to the original whose substitute is desired that differentiates 
this formula from a running mean of three. The place of this emphasis 
will be referred to below. This process may be done on a set of tabu- 
lated values by two successive sets of intermediates, as explained in a 
previous volume. 

Geometric Hann — This is the same process, done graphically on a 
curve already plotted, by taking each three successive points as the 
corners of a triangle. Consider that the first and third points form 
the base. From the center of the base, one-third of the way to the 
middle point will be the running mean of three, while one-half of the 
way from the base to the middle point will be the weighted mean or 
the "Hanned" value. This forms in practice a very easy way of 
smoothing a curve and has been very largely used in a slightly abbre- 
viated form which I have called the graphic Hann. 

Graphic Hann — The plotting paper used in the cyclograph needs 
to be 4 inches wide by some 45 inches long, fairly opaque, and with 
parts of the curve cut out so that light may pass through. All this is 
best done on rough brown paper cut in strips of the proper size. The 
present process, therefore, is to plot the tabular averages directly on a 
long strip of coordinate paper, using a rather large vertical scale, so 
that variations will generally be an inch or two high. This strip is 
placed upon the heavy strip of brown paper with carbon paper between 
and a blunted needle or pointer is passed slowly along the plotted 
curve, touching the points which by eye estimation and occasional 
measure should constitute the geometric Hann. Century dates at 
the same time are touched, so that the curve thus transferred becomes 
a satisfactory working smoothed plot of the standardized group 
average. This is called the graphic Hann and can be done quickly 
and accurately. This process of smoothing has a perfectly definite 
ideal to look to in case of doubt and I believe is almost entirely free 



44 CLIMATIC CYCLES AND TREE-GROWTH 

from erratic estimations, on account of which ordinary eye-smoothing 
may be criticized. The graphic Hann thus formed is the basis of the 
cycle plot whose process of formation will be continued below. 

Emphasis point — In the Hanning process just described the 
emphasis is laid on the middle point of the three. This has been used 
in so large a part of this curve-production that it is here given pref- 
erence. But there is some question about its use when conservation 
is considered, for it intimates a reversed or negative conservation in 
the last year of the three (see p. 101). If rainfall is retroactive, that 
is, if it affects rings already formed, the tree records ought to show 
some anticipation of abrupt changes in the rainfall. On the other hand, 
placing the emphasis on the last of the three years used amounts to 
admitting a conservation of moisture from the two preceding years. 
On the whole, it is felt that middle-point emphasis has given more 
satisfactory curves than emphasis on the final year. 

Cutting-line — The cycle plot has the maxima of the curve cut out 
so that light may pass through. The curve produced by the graphic 
Hann forms the upper side of this area to be cut, but the position of 
the base of the cut area has proved very important in the successful 
use of the analyzing instrument and therefore I have always had the 
curves at that stage returned to me to have the base or "cutting-line" 
marked. In any analysis the variations of the curve are the important 
features; hence, if the cutting-line is placed along the X-axis or the true 
base of the curve, the variations are reduced to very small percentages 
of the total light coming through and can not be seen. Even when 
the cutting-line is placed at the lower minima, the light is so abundant 
that it is very hard to get the variations visually or photographically. 
After extensive trials of every sort of height for this line, I have come 
to the general plan of sacrificing about one-third of the vertical height 
at the bottom of the minima and marking a long, sweeping line nearly 
straight, but not entirely so, as that brings the best display of varia- 
tions within the range of the instrument and has not been found to 
affect the results. 

The range of the instrument as now in use is confined to periods 
between 6 and 32 years (see "Recent changes," below). The cutting- 
line, therefore, to show these best, may be curved so as to cut out or 
reduce longer periods. They, however, are taken care of by plotting 
at a reduced scale. This has been done extensively with long sequence 
of rings extending 500 years or more. 

Cutting the plots — The final work on the cycle plots is cutting out 
the maxima, which, of course, is a simple matter usually done with a 
razor blade. 



INSTRUMENTS AND TECHNIQUE 45 

THE CYCLOGRAPH (PERIODOGRAPH) 
COMPARISON OF ANALYZING METHODS 

This study of tree-rings has become a study of the history of 
climatic cycles. The technique so far described covers the production 
of tree-record curves ready for analysis by a special instrument 
designed for the purpose and called a cyclograph. The number of 
curves to be analyzed is so great and the data sought so complex that 
this work would hardly have been done by a mathematical process. 
Harmonic analysis in its mathematical form has been so successful in 
numberless studies that many investigators have come to regard it as 
essential. A very clever illustration of its power is Miller's reduction 
of a facial contour to a mathematical formula which when plotted 
reproduces the contour. Of course, this was done by combining a 
long descending scale of period lengths with the distribution of empha- 
sis (amplitudes) on just the right ones. But after this beautiful illus- 
tration we must not forget that this form of contour analysis has 
nothing to do with the physical causes of the contour, nor does it help 
us in predicting other contours. It is like a photographic plate: it 
merely places that one on record. 

So in the case of the sunspot cycle, we can reproduce the known 
historic sunspot curve by 20 harmonics with different amplitudes, but 
when done we can not insist that the sunspot variation is really built 
of those harmonics. So also with climatic cycles, we do not know yet 
how far their physical causes are harmonic, and therefore the expression 
of climatic variations in a Fourier series begs the question. Evidence 
in a later chapter suggests distinctly that climatic cycles are simple 
fractions rather than harmonics of a fundamental. So the photo- 
metric process described below is permissible. Add to this its rapidity,, 
which is of the order of 50 times as great as the mathematical process, 
while its flexibility belongs to a different class altogether. The mathe- 
matical process is not flexible at all in the sense this is. The process 
here used bears somewhat the relation to the mathematical process 
that calculus does to algebra; it is differential. In applying a cycle 
to a long sequence of values, one sees at once at every point how far 
the values depart from the cycle. A varying cycle enters simply as a 
curved line, while a fixed period appears as a straight one. Two 
interfering cycles, forming a false third, enter as two straight lines or 
bands intersecting and their intersections form the third. In this 
process the operator not merely gets an analysis of the whole sequence 
of values, but of every possible fraction of them, an accomplishment of 
the highest difficulty in any mathematical solution. For example, 
Schuster analyzed the sunspot variations since 1750, dividing the 
whole series into two parts, and missed the points of discontinuity 
near 1788, 1830, and so forth. These discontinuous points are the 
most conspicuous features of the cyclograph analysis here used. 



46 CLIMATIC CYCLES AND TREE-GROWTH 

On the other hand, some will object, and correctly, that the cy olo- 
graph process does not give in figures the harmonic constants. Two 
points answer this; the first is that the cycle must first be caught out 
of a very complex combination of variables, and second, when the 
cycle is known it is easy to get its constants by mathematics, if desired 
(or by photometric means from a cyclogram). 

PRINCIPLE OF THE CYCLOGRAPH 

The earlier forms of the instrument have been described in the 
previous volume and need no repetition. The principle also was 
explained, and is briefly outlined here only as an introduction to the 
present form. The maxima of the curve to be analyzed are cut out, 
so that light passes through in proportion to the ordinates, as already 
described under the title Cycle plots. The horizontal spacing of the 
maxima of light is emphasized if the cutting-line is high, leaving the 
extreme minima without illumination. Now let us imagine a plot of 
this sort consisting of a series of evident maxima which seem to be 
equally spaced (as in the sunspot curve), and we wish to find if they 
are strictly periodic. We illuminate the curve from the back, place 
a lens at some distance before it, find the image cast by the lens, and 
compare the white spots in the image with an adjacent series of dots 
which we have placed on exactly equal spaces. If the dots are closer 
than the maxima, the lens is carried farther from the curve, reducing 
the separation of the focal images until they coincide in the average 
with the equally spaced dots. Then we see clearly that the maxima 
largely match the dots but in certain places; let us say, they draw 
away. These departures let us call differentials. 

So long as differentials take place in their own line (like the longi- 
tudinal vibrations of sound) it is hard to estimate them, but if these 
differentials can be turned out perpendicular to the line of the curve, 
that is, made transverse (like fight- waves), it is very easy to see and 
measure them. This is very easily done by extending both maxima 
and dots indefinitely in the transverse direction but at a small angle 
to each other. This effect is produced on the curve image by adding 
a cylindrical lens which converts each maximum of the focal image 
into a vertical band. The same effect is produced on the dots by 
inserting in their place a series of equally spaced nearly vertical opaque 
parallel lines. To give these lines accurately, a ruled screen such as 
that used in photo-engraving is placed at the focus of the lens and 
the row of vertical bands comes through the slightly inclined trans- 
parent spaces between the lines. This produces an interference which 
should be seen to be appreciated. If the maxima are equally spaced, 
they come through as straight horizontal rows of white spots, but 
where differentials occur, the spots are displaced above or below the 
i straight line. Departures from a perfect period are at once recognized, 



INSTEUMENTS AND TECHNIQUE 47 

because longitudinal displacement has been turned to transverse, 
thus making a departure from a straight line which is at once apparent. 

Invention and name — This pattern was first designed by the writer 
in 1913 and published in 1914 under the name of a multiple plot.* 
Its automatic production by this method of interference was worked 
out that same year and published in 1915. It was then called a 
differential pattern and was used as the basis from which to photo- 
graph a true periodogram, as described in Volume I. In the present 
volume, however, the periodogram is omitted, since there has been 
very little use for it in comparison with the pattern. With the con- 
struction of small portable instruments for producing this pattern, 
the word cycloscope has come into use as their name. In a correspond- 
ing way the large analyzing instrument with its photographic attach- 
ment, constructed with the fund given by Mr. Clarence G. White, of 
Redlands, California, has come to be called the White cyclograph; 
the photographs obtained by it are here called cyclograms. 

THE WHITE CYCLOGRAPH 

During the building of the previous instrument in 1918 the thought 
in mind was the production of a periodogram as suggested by Schuster. 
But with the extensive use of that instrument it became apparent 
that the differential pattern or cyclogram designed as merely one 
stage in the process was far more important than the periodogram. 
The periodogram merely produces the kind of results that come from 
a mathematical process; the cyclogram contains far more than that. 

At the same time, the long track of the periodograph compelled 
the observer to walk indefinitely back and forth in an awkward 
position. So it was first intended to arrange a mechanism to eliminate 
this walking, but as it took form the lessening importance of the 
periodogram was realized and the attachment for producing it was 
omitted. It could, however, be added at any time if thought worth while. 

Illuminator — The arrangement for mounting the cycle plot so 
that fight comes through in the proper way is called the illuminator. 
For a long time daylight was used, thrown onto the curve in a dark- 
ened room by a slant mirror at the base of a window. Then thin 
white tracing-paper replaced the mirror and gave a broad area for 
comparing different curves. One curve some 40 inches long and 4 
wide was insufficient and a second could be put above it. But for close 
comparison of many curves for dating purposes a light frame sliding 
vertically was arranged to carry 10 curves at once. This frame was 
suspended by a cord over a pulley and analysis could pass from one 
curve to another at any desired speed. 

*It appears to be identical with Clayton's "phasogram" in World Weather, page 379. The 
multiple-plot method of making a periodogram was described to him in conversation in the 
summer of 1913, and he remarked, "Well, you might expect an astronomer to work out an optical 
method." 



48 CLIMATIC CYCLES AND TREE-GROWTH 

When it became necessary to move the instrument to a locality 
where a suitable window was not available, 10 electric lights in a row 
were used, with a mirror behind and several thicknesses of ground 
glass between the lights and the curve to spread the light evenly. 
This is mounted on a table or stand, but it is planned to combine all 
this equipment with an attachment which will permit the curve to 
turn on its center through a horizontal angle, for by this means the 
range of analysis can be greatly extended beyond the previous 32 
years. This slanting of the curve can only be done when it is at 
maximum distance from the lens, for the two ends would come in at 
obviously different scales. To do this the whole illuminator will have 
to turn on a central vertical axis. 

Track and carriage — The cyclograph track is 18 feet long (see 
Plate 5, C), made of light beams well braced, carrying cross-pieces, 
notched at each end to hold two lengths of i-inch round steel shafting 
which serve as rails. The rails are 18 inches apart. The carriage has 
two grooved wheels on one side to run on one rail and hold the align- 
ment. On the other side is a single flat wheel.* The carriage holds a 
vertical mirror 30 inches wide and 15 inches high, facing the illumin- 
ator and the analyzing-box. Seen from the mirror, the former appears 
slightly, but directly, above the latter. The carriage is moved by a cord 
passing over a small wheel at the outer end and a drum with small spiral 
groove about it at the observer's end. This drum has a handle within 
reach of the observer as he sits at the side of the analyzing camera. 

Scale — The scale runs along the side of the track and the carriage 
has a mirror and light so arranged that the observer may see the 
lighted scale at any position of the carriage. A small telescope is 
provided for reading the distant positions. The graduation is put on 
from standardized curves, which are always kept on hand and measured 
and tried from time to time. In dry climates all curves shrink per- 
ceptibly and thus scales have to be watched. 

Range extension — The actual length of the track covers a range of 
periods from 5 to 18 years. In order to increase this to 32 years, two 
mirrors have been used, one fixed high above the track, throwing a 
beam back toward the analyzing-box, and the other at the front of 
the box in this beam, so placed that when it is raised in position it 
catches the beam from the first extra mirror and sends it to the mirror 
on the carriage, at the same time cutting off the direct light from the 
curve to the carriage. This nearly doubles the maximum path of the 
fight from the curve to the analyzing-box and increases the range of 
periods tested from 18 years to over 32 years. 

Camera inclination — One bit of awkwardness remains in this 
design, namely, the necessary change of slant of the camera-box when 

♦This same carriage was used on September 10, 1923, in photographing the total solar 
eclipse from the University of Arizona station at Port Libertad, Sonora, Mexico, with a 40- 
foot horizontal telescope. 



INSTRUMENTS AND TECHNIQUE 49 

the movable mirror is changed in distance. In order to get the reflec- 
tion from the mirror properly placed, the box has to have its plate end 
lowered when the mirror comes near. 

Cyclograph camera — By the track-and-mirror arrangement, above 
described, the observer can stay at one point while the moving mirror 
changes the effective distance between the curve and the lens, and 
by changing the size of the focal image brings into view all the range 
of periods of which the instrument is capable. 

Lens. — The lens is a Tessar II B of 6 inches focus and about 
i-inch aperture, with a negative cylindrical simple lens of —6 inches 
focus with horizontal axis, so that in the vertical direction it neutral- 
izes the action of the main lens. Without the cylinder there is an 
ordinary image at 6 inches. With the cylinder all the horizontal spacing 
comes in as before, but there is no vertical focussing; consequently, 
each maximum in the curve appears in the image as a vertical band 
whose intensity is proportional to the height of the maximum. 

Automatic focus — The lens is mounted as in previous instruments 
inside and on the base of a suspended parallelogram with hinges at 
each angle. The length of the parallelogram extends along the axis 
of the instrument, in line with the track. This permits a focussing 
motion of the lens in its axial line. From the front of the parallelogram 
a lever-arm extends downward and is attached by an adjusting-screw 
to a horizontal rod passing forward toward the axis of the drum which 
moves the mirror-carriage. A cross-piece on the rod bears against a 
brass spiral mounted near the axis of the drum and turning with it. 
This spiral is so arranged that as the drum turns, the position of the 
lens changes and the focus is maintained in a fixed plane. 

Analyzing-plate — The analyzing-plate is fixed at the focus of the 
lens in a brass mounting attached to the back of this front compart- 
ment of the analyzing-box. The mounting has been elaborate enough 
to test many details and is rather more complete than ordinarily 
needed. On the fixed plate is a circular brass plate which can be 
rotated through 45° against a graduation in degrees. A rectangle 1 
inch high and 2 inches long is cut through the circular plate, and on 
this rectangle is mounted the analyzing-plate, covering a little more 
than the rectangle. The ruled lines of the plate are vertical, that is, 
parallel to the short side of the rectangle. In normal position the 
circle is clamped so that the fines are inclined 12° from the vertical, 
and therefore 12° from the vertical bands in the image. 

The plate itself is made of two screens accurately ruled 50 lines 
to the inch, face to face, one fixed and the other with a slight motion 
controlled by a screw. The purpose of this is to change the relative 
size of the transparent part of the ruling without changing the distance 
from center to center of the fines. In each screen the opaque ruling 
is equal in width to the transparent space between. So by moving 



50 CLIMATIC CYCLES AND TREE-GROWTH 

one screen slightly across the other, the transparent part can be 
changed from zero up to 0.01 inch. The width found advantageous 
is 0.004 inch or two-tenths of the spacing of the lines. 

Visual compartment — From the analyzing-plate the light passes 
into the middle or visual compartment through the condensing-lenses. 
These are two 6-inch positive cylindrical lenses with vertical axis, so 
that the eye placed 6 inches away may receive all the light from the 
plate and see its whole area. It is more convenient to have the observer 
at the side than at the end, where he may interfere with the light 
coming from the curve beyond, so back of the condensers is a vertical 
mirror on a hinged support. When the support is pulled forward, it 
takes a position at 45° and throws the beam out at the side through a 
small lens and to the eye. The lens puts the image slightly out of 
focus to the eye, as in such condition the eye recognizes alignments of 
blotches better. 

Photographic compartment — When the mirror-support is thrown 
back out of the way, the beam goes straight on to a triple lens of 3 
inches focus, which reproduces the analyzing pattern on a ground 
glass in the third and last compartment. This last compartment is 
held separate on a clamp by which the ground glass may be brought 
to the most advantageous focus. A plate-holder fits in place of the 
glass and may occupy three slightly different positions, so that three 
exposures can be made on the same plate. 

Recent changes — The above description gives the form of the 
instrument used in the cycle analyses in this volume. But since 
writing this chapter added floor-space has made it possible to lengthen 
the track to 40 feet. With this the two extra mirrors have been 
removed, together with the automatic focussing device and scale 
illumination, and a small convenient scale is now located directly in 
front of the observer. 

CYCLOSCOPE 

A small portable analyzer has been constructed for exhibit pur- 
poses, but fully equal to real analyzing work. It consists of a small 
illuminator with a long electric light inclosed and cord to be attached 
to a wall-socket. Curves 10 inches long may be placed in this. The 
analyzing part is a box 12 inches long and 4 inches square, with top 
which opens on a hinge. It carries a convex spherical and a cylindrical 
lens at the front, with a little chance to focus by hand; then a simple 
analyzing-plate fixed at the proper inclination; then condensing- 
lenses and an eye-lens. One looks through it toward the illuminated 
curve and walks nearer or farther and watches the changing pattern. 
When a cycle is indicated by proper horizontal alignment of spots in 
the analyzing pattern, its value may be found by a simple formula 
after measuring the distance from the lens to the illuminated curve. 



VI. TREE RECORDS: LENGTH 

The first definite purpose in making the collections here described 
was the extension and improvement of the 3,000-year sequoia records 
presented in the previous volume. This was followed by a similar 
plan in regard to the yellow pine as soon as certain probabilities 
of extension were realized. The present chapter deals with these 
attempts. As the number of specimens grew and material came from 
many sources, the study of local and continental topographic effects 
took shape and has become a central theme of this volume, as indi- 
cated in the succeeding chapters (VII and VIII). Finally, large 
quantities of early historic, prehistoric, and geologic material came 
to the laboratory and the problem was presented of reconstructing, 
in part at least, the climates of past ages by such indications as could 
be found in tree-rings. Hence arose the thought of collecting and 
formulating climatic indicators in trees (VIII). All this is of funda- 
mental importance in the continued investigation of climatic cycles 
and tree-growth (IX). 

OLD SEQUOIA RECORDS 
THIRD SEQUOIA TRIP, 1919 

The trip to the groves near General Grant Park in July 1919 was 
made for the purpose of determining the status of a certain ring called 
1580 A, which was in doubt because it had appeared in less than half 
of the 23 specimens at that time in hand. It was also planned to make 
a topographic study of the influence of the immediate environment, 
especially ground-water, on ring-growth. After a trip to Wigger's, 
just south of the Park, to see an immense stump, and after an examina- 
tion of the General Grant tree to estimate its age, I went to Hume and 
on the 12th accompanied a guide to the farthest parts of Camp 6, 
where Nos. 1 to 5 had been collected, and selected new specimens for 
cutting. The next day, with burros and a helper, camp was made at 
the mouth of Redwood Basin, near the spring. With no one to help, the 
radial pieces cut here the next morning were not on the scale previously 
obtained. Instead of being 6 or 8 inches wide and deep, they were 
about an inch in those dimensions. This meant their breaking into 
many small pieces, which were immediately put into small marked bags. 
The new specimens supplemented the 13 already obtained in that 
district and gave opportunity of testing more thoroughly the relation 
of sequoia growth to ground-water, which will be discussed in a later 
chapter. 

The next day we cut a new radial from D-12 in Indian Basin, 
which had previously failed to give a satisfactory dating on account 

51 



52 CLIMATIC CYCLES AND TREE-GROWTH 

of badly compressed rings near the outside. A good radius was 
selected and a conspicuous ring was traced across from the new radius 
to the old and its position on the old accurately determined. It 
proved very easy to extend the dating on the new radius back to this 
ring, and with this good start the entire dating of this tree proved 
very satisfactory, in spite of the complacency of its growth. 

We returned to the Park and the next day I cut radials 32 to 35 at 
Converse Hoist. These supplemented the two obtained the year before 
in that vicinity by going higher up on the ridges for Nos. 32 and 35 
and nearer the creek for 33 and 34. 

This locality is a very interesting one, because it contains the 
stump D-21, which had 3,200 rings in it, whose central rings were 
shown in Plate 1. Very old trees are rare. I have examined many 
hundreds of stumps, made estimates of their age, and in many cases 
have counted the rings. There were in these forests many trees over 
2,000 years of age, but probably very few over 3,000. Only 3 stumps 
of this age are known so far. Two estimates of the General Grant 
tree gave 2,000 and 3,000 years of age, and its true age is thus taken 
as 2,500 until some better opportunity comes for getting its number of 
rings. The Centennial stump nearby was estimated to have some 
1,800 rings and the large stump with raised center at Wigger's probably 
is 1,500 years of age. 

FOURTH SEQUOIA TRIP. 1924 

The fourth sequoia trip in July 1924 had two objectives; first, the 
improvement of the general sequoia record, and second, the securing 
of certain indicators needed in the problem of correctly dating large 
numbers of prehistoric tree-sections from the ancient ruins of the 
Southwest. Such dating would not only help the archaeologist, but at 
one stroke would also extend the superb yellow-pine climatic record 
by more than 300 years at least. The general problem of dating 
unknown tree-records will be taken up at another time. It is sufficient 
to say here that one way to accomplish such dating is by cross-identifi- 
cation between the pines of the Arizona region and the sequoias of 
California. This apparently would be easy by comparison of the 
occasional common deficient years, perhaps eight per century, except 
that in about one-fourth of such cases the Arizona deficient year 
occurs one year late. For example, the small sequoia rings for 1846, 
1812, 1541, and other years in California come in 1847, 1813, 1542, 
and so forth, in Arizona. The attempt is, therefore, now being made 
to discover in the pines or sequoias, or both, some internal signs by 
which to know just when this difference of one year is to be expected. 
Hence, in approaching this problem from the sequoia point of view, it 
seemed best to go to other sequoia groves and see if some indication 
of this occasional discrepancy could be discovered. 



TREE RECORDS: LENGTH 53 

Accordingly, a trip to the northerly Calaveras Grove was made in 
early July 1924, by stage from Stockton. This grove was the first 
one discovered and the marble slabs with tree names are reminiscent 
of the pioneer days. The hotel is picturesquely situated at the edge 
of the grove and nearby is the Dance Hall mentioned by Mark 
Twain. This hall is on the stump of the first big tree cut (1853) and 
the early difficulty in penetrating such immense trunks is apparent, 
for in this case it was done by large auger-holes made on opposite 
sides toward a selected diameter. These holes show in the great butt- 
log still lying close to the hall. This tree was quick-growing and 
estimated to have some 1,200 or 1,400 rings only. It was probably 
the one from which a tracing of the whole set of rings was made 
about 1865. 

The road, as it approaches the hotel, formerly passed between the 
"Sentinels," two fine sequoias, but one had fallen the previous year 
and a boring in it at some 50 feet from the original ground-level, 
checked by a similar boring from another fallen tree, gave a perfect 
start in dating the trees in this grove. This actual dating, however, 
proved unnecessary, for it was perfectly easy to date all the records 
obtained by comparison with the known records in the more southerly 
groves. The trees in this grove are standing and, therefore, it was 
difficult to get any satisfactory radials. However, a very few old 
trees had fallen and small pieces were cut from three in inconspicuous 
places by which the record was carried back some seven centuries. 
Incidentally, this dating of fallen trees gave excellent data on the dura- 
bility of sequoia bark and sap wood already referred to. 

This grove is small, perhaps one-third of a mile across, and lies in a 
flattish, slightly depressed area with drainage to the southwest and 
protected on the other sides by hills and ridges a few hundred feet 
high. Its elevation is 5,000 feet and the precipitation in this neigh- 
borhood is probably near 40 inches, mostly in winter. The ring- 
growth is very complacent, with deficient rings showing but rarely. 
The average size is smaller than expected. The easy cross-identification 
with the tree records in the other groves shows that the entire area of 
Sequoia gigantea in California is essentially a unit in its climatic reaction. 

A full day was given to collecting yellow-pine borings in connection 
with the study of modern tree-records over the whole western area. 
Trees were selected in an east-and-west line across the grove from the 
hilltop back of the hotel to the ridge on the east, where the main 
highway passes and the trail to the South Grove branches off. These 
pines cross-identify well and are included in the western groups under 
the abbreviation CVP. Eleven trees comprise this close group, but 
three more were added at elevations nearly 2,000 feet above sea-level 
in the vicinity of Murpheys. These three, however, give essentially 
the same record as those near the grove and are included in the CVP 



54 CLIMATIC CYCLES AND TREE-GROWTH 

group. The Calaveras Grove of sequoias is privately owned and 
these specimens were obtained by courtesy of Mrs. Whitesides, in 
charge at the hotel. 

FIFTH SEQUOIA TRIP. 1925 

The dating of the specimens from the Calaveras Grove led to the 
conclusion that the tree-records there resemble the Arizona pine-tree 
records less than the sequoias farther south, instead of more. So it 
only remained to visit the most southerly grove near Springville and 
secure better material than already collected there. In 1918, two 
3,000-year old radials had been secured from the Old Enterprise mill- 
site. These both cross-identified with trees 50 miles north near the 
General Grant Park, but while the cross-dating was absolutely reliable, 
the resemblances were not so close as hoped for and were not equally 
good in the two trees. No. 23, age 3,100 years and growing near the 
drainage brook, showed less agreement than No. 22, age 3,000 years, 
growing near the center of the grove. Accordingly, the trip was made 
by auto from Pasadena to Springville on August 4, 1925. Mr. Charles 
A. Elster, of that city, met us and next day took us to his Camp 
Lookout and sawmill in the pines at an elevation of about 5,000 feet 
above sea-level. After lunch he drove us up the steep grades, past 
the old Frazier mill-site of 1885 and the Elster mill-site of 1901, to the 
Enterprise site of 1898. The Conley mill of 1892 at Brownie Meadow, 
off the road to the north, was close to D-49, which had been cut by 
Mr. Elster himself in 1892. Mr. Elster had worked here in the lumber 
business almost since its beginning and his recollections were of the 
greatest help. The afternoon was devoted entirely to the selection 
of suitable stumps for cutting. It seemed advisable to get the very 
oldest and, if possible, to exceed the previous maximum of 3,200 
years (but that hope was disappointed). At the same time it was 
desired to get a range of younger trees in order to develop an improved 
system of age corrections. 

The next day the cutting of radials began. This was done by 
two helpers in charge of Mr. P. W. Weirick, of Pasadena, who very 
kindly assisted me on this trip, thus enabling me to spend the entire 
time in the selection of specimens. So two days were spent in this 
way and in securing specimens of pine growth (see p. 88), and on 
Saturday, the 8th, Mr. Elster took us to Balch 's Park to see the marvel- 
ous old tree appropriately named Methuselah. That afternoon we 
returned to Springville and the next day to Pasadena. 

On returning to Tucson, several of these long sequoia records were 
dated, including one of 2,600 years, but it finally seemed best to 
postpone the complete study of this material to a time when proper 
attention could be given to old and prehistoric records in connection 
with climates of the past. Hence, its further discussion will be reserved 
for another time. 



TREE RECORDS! LENGTH 55 

COAST REDWOOD RECORDS 

The value of very long and old ring records is so obvious that 

every effort has been made to discover them. The coast redwood is a 

very available tree, growing to a great age, but its preference for the 

coast's even climate and its avoidance of winter snows led many years 

ago to doubts of its usefulness in these ring and climate studies. 

Moreover, about 1912 the late Julius Kapteyn did some counting on 

the rings of the coast redwood in the hope of finding climatic or solar 

correlations, but was disappointed. At any rate, the possibility of its 

usefulness deserved a real test and two groups of this species have been 

collected. 

SANTA CRUZ GROUP, 1921 

A trip made on February 20, 1921, was arranged through the 
kind assistance of Mr. R. E. Burton, of the high school in Santa Cruz, 
who took me out some 15 miles in a northerly direction from that city 
to a point near Major's Creek, where redwood trees had recently 
been cut. This location was in the upper part of the low range of 
coast hills, but on the eastern slopes, so that the drainage was toward 
the northeast and inland at that point. The first trees selected were 
at the upper end of a gully, often dry; others were cut in the valley 
bottom and others on the very steep slopes of a side-wash. The 7 
specimens collected there were studied for months and no satisfactory 
cross-identification was found. Trees 10 feet apart cross-identified 
and gave apparently good records, but other trees 50 yards away 
gave a different record which could not be identified with the first. 
In the outer parts of some good specimens the rings would interlace 
in a way never noted in the big sequoia; for example, some red rings 
merged in one direction with the ring next outside and in the opposite 
direction with the red ring next inside. Dating was therefore hopeless 
and has not been accomplished to this day. The general age of these 
trees was not great, probably from 300 to 700 years. 

SCOTIA TRIP, 1925 

The above negative result was not conclusive, for it might be a 
characteristic of the locality chosen or of the southern redwoods only. 
So the long auto trip of June 1925, described later, was directed to the 
redwood region of northern California. We motored from Grant's 
Pass, Oregon, to Crescent City, on the extreme northern coast of 
California, and thence through those wonderful redwood groves to 
Eureka and Scotia. At Eureka, the center of the redwood-lumber 
industry, I consulted representatives of the Forest Service and was 
referred to Mr. Percy J. Brown, whose mill and forests were on or near 
the main highway to the south. The general area included a square 
mile or so of bottom land some 30 feet above the level of the Eel River. 
This land rises very gently toward the hills on the south, but the slope 
5 



56 CLIMATIC CYCLES AND TREE-GROWTH 

grows steeper in the outwash-fan from a small canyon entering the 
hills. Twelve stumps were selected of different sizes and at various 
scattered points. Of these, three were high up on the ridge forming the 
east side of the canyon. Here the cutting had been done some years 
and the young sprouts of redwood from the stumps formed dense and 
tangled masses which had to be cut away in order to get at the stumps. 
In the bottom lands below the cutting had been recent, some of the 
trees having been felled only a few weeks, so there was no difficulty 
about getting the final dates. The v-cuts were 4 to 6 inches wide and 
deep and thus were excellent specimens, well selected and in perfect 
condition. They were prepared and mounted by Mr. Swan Erickson 
at Tucson under my direction and cross-compared by him and later 
by me, but no cross-identification was found. Some of the bottom- 
land specimens seemed to have perfectly clear records, yet with close 
study the different trees did not agree. It may be that further study 
will produce some way of using these good specimens, but so far they 
are not usable in this study of climate and solar activity. This is 
unfortunate, since many of them carry records over a thousand years 
in length. 

DEFICIENCY OF THE COAST REDWOOD 

Though it is true that years ago the theory was entertained that 
winter snow is important in producing trees that give good climatic 
records, this failure of the coast redwoods was a surprise. Probably 
the subsoil water-supply and certain habits of the tree itself increase 
these nonclimatic variations. The trees get much moisture from the 
coast fogs, and Mr. W. P. Hoge, of Mount Wilson, tells me that in a 
fog the trees show some very curious anomalies in their capacity to 
take moisture from the air. Again, if moisture is in too large a quan- 
tity, sunshine would be the controlling factor in growth, though this 
is not at all likely in the southern groves. But a greater difficulty lies 
in the way these trees reproduce after fire, which is by sprouts from 
the base of the mother tree. Hence, these trees when near together 
are apt to be connected underground. This method of reproduction 
leads to very erratic growth, as observed by Dr. Emanuel Fritz, of 
Berkeley. In a letter dated May 15, 1923, he says: 

"This section of second-growth redwood is interesting because it 
shows a large number of rings merging into one and thus on some radii 
giving an incorrect indication of the age of the tree. In March we cut 
three-quarters of an acre of second-growth redwood 65 years old and 
under, and found to our amazement that trees were older at the top 
than on the stump. Very careful study soon brought to light the fact 
that we were not counting the rings on corresponding radii. After 
this discovery we had no further trouble. As you know, redwood 
sprouts very freely from the stump. As these suckers mature, they 
crowd out one another and leave but two or three in a clump. Often 



TREE RECORDS: LENGTH 57 

the cambium layer is common around the group. We noted that on 
that side of the tree which faces closely another sprout, there is a 
dearth of growth-rings. On that side also there is practically no foliage 
clear up to the tip. The most peculiar thing about this lack of ring 
formation on one side is the sudden change from the normal to the 
abnormal." 

In another letter soon after, he says: 

"The trees cut in this experiment .... were many of them 
sprouts. Two to six sprouts, 15 to 35 inches in diameter at breast 
height, were found around many mother stumps. This sprout-clump 
habit makes the trees touch one another at the base (sometimes after 
50 years to develop a common, or rather a continuous cambian ring 
for two or three trees at stump height) and to be separated at the top by 
3 to 6 or more feet. Tree No. 90, from which the specimen was cut, 
was of this class. The crown was all on one side. The most difficult 
thing to explain in the specimen seems to me to be the reason for the 
sudden change from normal growth to asymmetry and then a return 
to the normal." 

The coast redwood may some time be used in the study of climate 
and solar activity, but its interpretation is so complicated that for the 
present it can not be included in this study of modern and historic trees. 

OLD PINE RECORDS 

For climatic records involving rainfall as the most important 
factor, no tree has yet been found superior to the yellow pine of the 
arid Southwest. It combines a wide range of growth with excellent 
sensitiveness and a reluctance to drop rings completely in deficient 
years (as the junipers do). Next to it, perhaps, comes the Douglas 
fir, which has larger growth with usually greater sensitiveness, so that 
for the same size of trunk it has fewer rings with over-exaggerated 
representation of climatic changes. Therefore, extension of climatic 
records in the pine trees is most desirable. 

SEARCH FOR OLD TREES 
In the summer of 1919, Flagstaff was visited primarily for the 
purpose of investigating certain buried pine trees in the recently 
filled land immediately north of town, which will be described in 
another place. September 10 was spent in a "University" section, 5 
miles south of town, a section which had long been pointed out as 
having most beautiful pines with clear trunks, suitable for fine lumber. 
These trees were on nearly level limestone, breaking to lower levels at 
their south edge and protected to the west by the volcanic bulk of 
Woody Mountain. There seems to be no special protection from the 
occasional powerful northeast wind. This region had been cut over 
recently and it was easy to select the large stumps with fine grain. 



58 CLIMATIC CYCLES AND TEEE-GKOWTH 

Of the 8 radials cut (Fl-33 to 40), 5 had an age of 500 years. Only 2 
such trees had been found before. Thus by one day 's work a reliable 
500-year record was obtained (see Plate 6). 

Burnt centers — All this seemed so encouraging that on August 28, 
1922, another visit was made to this locality for the purpose of collect- 
ing " burnt centers." It had long been hoped that the tree record 
could be carried back before 1,400 a. d. by finding stumps or logs of 
earlier origin which in some way had been preserved. For example, 
a tree blown down by the wind might be buried and thus preserved, 
or it might have fire injury which would cause the central parts of the 
stump to fill with pitch and thus withstand weathering. So on this 
visit the larger burnt stumps were sought and partial radials cut from 
their centers. Out of 5 so collected, numbers Fl-95 to 99, one was 
too complacent for dating, 2 began about 1500 and 2 began before 
1400 a. d. Of these two, one undoubtedly started by 1350, but the 
very center had rotted away and no real gain was made. Yet these 
two were thoroughly filled with pitch and presented records which 
match in a remarkable manner certain dated beams from the pueblo 
buildings of the Hopi Indians. 

In the summer of 1920 two other 500-year trees were reported to 
me at about the same time. On June 17 a radial from Fl-41, a 66- 
inch stump in the northwest corner of Fort Valley, was cut. This 
very old tree stood at the edge of the flat valley floor, in good soil, 
near large outcroppings of volcanic rock, on which the Southwestern 
Forest Experiment Station stands. Mountains protected it to the 
west, north, and east, but not especially on the southwest and south- 
east, and southwest winds are sometimes very strong. 

On the following day another stump of even larger size was visited 
near the top of Woody Mountain, 10 miles to the south. This was 
numbered Fl-42. By courtesy of Mr. T. A. Riordan, president of the 
Arizona Lumber and Timber Company, a full section of this splendid 
tree was cut and shipped to Tucson. Each of these 500-year trees 
was somewhat complacent; in fact, they and the still older tree men- 
tioned below have decidedly less sensitive records than the previous 
7 trees of that age. Five of these 7 had come from the university 
section, some 3 miles east of Woody Mountain, and 2 collected in 1906 
had come from about 2 miles west of the same mountain. 

A 640-year pine — In early July 1923, Forest Assistant Merker 
and Forest Examiner M. Westveld discovered a pine stump in the 
canyon a mile up-stream (south) from Fisher's Tank and about 5 
miles southeast of Flagstaff. By their first count this tree was 640 
years of age when cut and subsequent examination confirmed that 
figure. By courtesy of Mr. G. A. Pearson, director of the Southwestern 
Forest Experiment Station, a large half section was cut for me and 



Carnegie Inst, of Wash. Pub. 289, Vol. II (Douglass) 



PLATE 6 



r* 



Q 




A. Site of 500-year pines, Flagstaff, Fl. 35, in foreground; looking south 




B. Stump of 640-year pine, Fisher's Tank, Flagstaff 



TREE RECORDS! LENGTH 59 

sent to Tucson, and later (July 13, 1926) he showed me the stump, 
of which I include here a photograph (Plate 6, B). The canyon is 
about 200 feet deep in the horizontal limestone strata and extends 
north and south. Water flows occasionally. The stump is on the 
east side of the canyon, 25 feet above the bottom and 50 yards from 
the usually dry wash. The slope of ground about it is about 30°. 
The date of starting was undoubtedly close to 1275 a. d. The earliest 
measured ring is 1284, but a serious injury occurred, probably in 
1294, greatly reducing the growth for some 8 years. Much decay has 
occurred at this point, and though the dating is probably correct, the 
normal values of the ring-width are profoundly reduced. Since the 
first hundred years in this record were new, three radii were measured 
and the average taken. The growth is somewhat complacent, but 
much information is given by it for that century. It is probable that 
important checks on it will be obtained from early historic beams in 
the Hopi pueblos. This discovery renewed interest in the search for 
very old trees, and it is possible that some living trees of similar age 
have already been found. 

Other 500-year pines — A 500-year pine was found in the group 
of 8 from the Charleston Mountains, near Las Vegas, Nevada. It 
showed with the other trees there a record rather intermediate between 
the Arizona and California values. Also a fine v-cut from a pine stump 
in the Crater National Forest of southern Oregon near Kirkford has 
been sent me by the kindness of Lumberman John D. Hoist, of that 
locality, acting for Mr. Fred Ames, assistant district forester at the 
Portland, Oregon, office. In this connection, also, one might mention 
the extraordinarily old juniper near Logan, Utah, of which a descrip- 
tion has come from Supervisor C. B. Arentson, located there. 

PREHISTORIC MATERIAL 

The search for old pine records has taken a new turn in the use of 
early historic and prehistoric pine logs in the Hopi villages and the 
ancient ruins of the Southwest. This really began in 1916, when Mr. 
Earl H. Morris, for the American Museum in New York, sent me 
several early historic logs from Gobernador Canyon, near Aztec, New 
Mexico. This led to a series of specimens from the ancient ruin at Aztec. 

Aztec sections — A trip to Aztec was made in August 1919. An 
examination of the logs in this ruin led to the construction of the 
tubular borer, which produces cores 1 inch in diameter, giving the 
series of rings from the outside to the center of the log without impair- 
ing its strength and without disturbing the original house construction. 
Following this visit, Mr. Morris spared no effort in getting me speci- 
mens from some 50 logs used in the construction of that wonderful 
ruin. Nearly all of these cross-identify perfectly in the Aztec-Pueblo 



60 CLIMATIC CYCLES AND TREE-GROWTH 

Bonito chronology. It seemed necessary to get some modern trees 
from that vicinity, so Mr. Morris took me 40 miles north to Basin 
Mountain, in southwest Colorado, where some 10 different trees were 
sampled. To these were later added 9 tree sections from a point 
about 20 miles east of Aztec. These together make a very satisfactory 
group known in my lists as the "Modern H's," H being the group 
letter applied to the old Aztec material. 

Chaco Canyon beams — The Aztec sections gave a fine ring record 
more than 200 years in length, but of unknown date. As soon as its 
real date becomes known, that much length can be added to the cli- 
matic record in the southwestern pines. An early shipment of Aztec 
sections included several from Pueblo Bonito in Chaco Canyon, some 
50 miles to the south. These specimens came from the American 
Museum in New York City, where they had been deposited by the 
Hyde Expedition 25 years before. Very soon these were found to 
cross-identify with the Aztec sections, and they began to improve and 
extend that prehistoric record. Then Mr. Neil M. Judd, director of 
the National Geographic Society Expedition at Pueblo Bonito, became 
interested in the possibility of developing the chronology of Pueblo 
Bonito by the ring records and he has collected and sent me nearly 
160 excellent specimens, mostly from that one ruin. Nearly a hundred 
of these I have been able to place exactly in the Aztec and Pueblo 
Bonito chronology. This chronology is referred to as R. D. or relative 
date, since its true location in our numbering of years, "Anno Domini," 
is unknown. This Pueblo Bonito material has increased the prehis- 
toric ring record so that it extends accurately from R. D. 230 to R. D. 
543, a range of 313 years. A single beam extends it with uncertainties 
about 40 years later. So if this material could be dated, some 350 
years of record would be added at one stroke. 

In connection with this collection two trips have been made to 
Chaco Canyon, one in early September 1922, to get a better knowledge 
of the beams there and of the problems connected with their dating, 
and the other in September 1926, to study the living pines in that 
region. On each occasion many specimens were collected, and on the 
second trip much was seen of special interest in connection with 
climatic indicators in trees, which will be mentioned in a later chapter. 

National Geographic Society beam expedition — It is evident that 
two different interests join in the attempt to date the beams in the 
ancient ruins of the Southwest, namely, the extension of climatic and 
solar records in trees, and the archaeological and human interest in 
the age of those wonderful ruins. For the second reason, the National 
Geographic Society has encouraged and supported the further collec- 
tion of early historic and prehistoric material and otherwise assisted 
in the dating ol these prehistoric beams. In general, two distinct 



TREE RECORDS! LENGTH 61 

dating methods are in view. The first is the " bridge" method, by 
which we start with old living trees and cross-date the early parts of 
these with late parts of earlier trees, and so on till a real ring record 
is built back to the age when the ruins were under construction. The 
other method is the "sequoia comparison" method by cross-dating 
with the sequoias, whose great age without doubt covers the period of 
building of these ruins. The best result would be one derived from a 
complete agreement of these two methods. Perhaps the stronger of 
the two methods is the first or bridge method, but it promises to 
require large collections from many different ruins, beginning with the 
early historic and going back to the period desired. Consequently, 
in June 1923 an expedition set out for the purpose of making such 
collections under the charge of Dr. J. A. Jeancon of Denver, assisted 
by Mr. O. M. Ricketson, of the Carnegie Institution. I went with 
them for the first 10 days in their visits to the Hopi Indian villages, 
where some 22 specimens were collected. They then continued the 
trip, covering generally the southwestern area, including such places 
as Canyon de Chelly, Chaco Canyon, Mesa Verde, and the Rio 
Grande Valley. To the present time their collections have not been 
finally and thoroughly examined (such work will be done in connection 
with the study of past climates), but it is practically certain that 
extensive gaps remain in the long interval from the Aztec and Pueblo 
Bonito chronology to a. d. 1300 or 1400, when the living trees began 
their record. Nevertheless, this bridge method is probably only 
delayed, for the collection from Pueblo Bonito reveals the possibility 
that in some Hopi Pueblo or late prehistoric ruin will be found beams 
cut in ages different enough to cover the long interval desired.* 

CALIFORNIA AND ARIZONA CROSS-DATING 

In the presence of the gaps above referred to, the sequoia com- 
parison method becomes of increased importance and has played an 
important part in directing our effort in the last few years. The visit 
to the Calaveras Grove in 1924 and to the Springville Grove in 1925 
were primarily to aid in this problem. The problem itself was stated 
above in describing the purpose of the fourth sequoia trip, page 52. 

CHARLESTON MOUNTAIN TRIP 

In connection with the dating problem between Arizona and Cali- 
fornia, the Charleston Mountains, at the southern extremity of Nevada 
and about midway between the Flagstaff area and the best sequoia 
region, were visited and collections made. Senator E. W. Griffith, of 
Las Vegas, Nevada, kindly took me out on July 9, 1924, by automobile 

*At the time of reviewing this chapter a group of 25 beams from " Wupatki" near Flagstaff 
has shown that this ruin was built some 30 years later than Aztec. It seems very probable that 
in time the "bridge" method will be successful. 



62 CLIMATIC CYCLES AND TREE-GROWTH 

some 30 miles west to the summer resort at about 7,500 feet elevation 
in these mountains. The resort is located in a large, deep canyon on 
the east side of the mountain and well up in the pines. A delightful 
brook runs much of the time. The ring record from the trees collected 
here is actually intermediate between Arizona and California, agreeing 
in some parts conspicuously with the Arizona trees and in other parts 
with California. The full discussion of these characteristics, in order 
to see whether they help to solve the cross-dating problem, is planned 
in connection with the study of past climates. 



VIL TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 

The understanding of any special distribution of ring characters 
over great areas is increased by personal acquaintance with the region. 
So, in addition to much travel in the Southwest, both within and with- 
out the State of Arizona, the writer has made two special trips in the 
study of geographical distribution of tree-growth. 

WESTERN CIRCUIT, 1925 

This trip was made easterly from Tucson to the Rio Grande Valley, 
thence up-stream to Albuquerque and east again to Santa Fe, where 
the SF group had been collected in 1922; thence through the pine- 
covered mountains to Las Vegas. Halfway between these cities we 
passed Pecos, where the "L" group of four trees had been obtained, by 
aid of the Forest Ranger. However, only one of these proved suitable 
for dating, and so this is not retained as a group. The next day car- 
ried us over the wide elevated plains of northeastern New Mexico to 
Raton, whose mountain pass through the Rockies is high enough to be 
pine-covered. Three of the trees near the road were bored, but only one 
could be dated reliably, and as we already had a group from Cloudcroft, 
New Mexico (CC group), this single tree is omitted. Later we went 
along the eastern base of the mountains to Fort Collins, Colorado, 
and Laramie, Wyoming. In the low hills between these two places, 
the group LW (Laramie, Wyoming) was collected near the road. 

The eastern face of the Rocky Mountains, extending north and 
south for many hundreds of miles, is a striking feature of western 
contours, and the groups in New Mexico, Colorado, and Wyoming 
along this line and partly also the small Yellowstone group from 
Specimen Ridge in the northeast corner of the park (collected in 1920) 
give certain interesting characters which will be referred to later. 

The next stop for collecting was 60 miles northwest of Baker, 
Oregon. At a point where pine trees border the road as it passes over 
the Blue Mountains, the BO (Baker, Oregon) group of 8 was collected. 
On the eastern slopes of the hills near the road at The Dalles are more 
yellow pines, of which a small collection was made, known here as the 
DL (Dalles) group. In the low coast hills 25 miles northwest of Port- 
land, a large group of Douglas firs was collected in 1912, as described 
in Volume I. It now appears that this group, called OC (Oregon 
Coast), does not cross-identify with the other western groups, probably 
because its location close to the coast gives a very different climatic 
environment. 

The primeval forests of the State of Washington were extensively 
cut along the settlement-line marked by the highway between Port- 
land and Seattle. Much of the land was burnt over and the huge 

63 



64 CLIMATIC CYCLES AND TREE-GROWTH 

burnt stump is a common sight. Stumps were examined in different 
places and ring samples were collected at Victoria, British Columbia, 
at Blyn, Washington, and at Toledo, on the Oregon coast, but the 
growth was so exceedingly complacent that no special effort was made 
to form a group. However, there is no real doubt that group char- 
acters will show, if the right tree and location are found. 

WESTERN CONTOURS AND RAINFALL 
The important mountain ranges of the western States extend in 
north-and-south rows, whose western slopes precipitate moisture from 
the westerly winds. The long valley running north from the Gulf of 
California, with the smaller parallel San Joaquin Valley in central 
California, is the driest area, because the westerly winds are drying 
winds as they descend into them. 

Mechanism of Arizona summer rains — The maximum rainfall on 
the coast is in winter, but the maximum in the northern parts of the 
dry valleys just mentioned is in late spring, when their warming 
causes the air to rise and move to the east and "pull" in the wester- 
lies. In midsummer it is so hot that the moisture is reabsorbed even 
before it falls and the amount that reaches the ground is small. The 
same summer "pull" draws moisture-laden air from above the Gulf 
of California far to the south (whose water temperature at Port 
Libertad in September 1923 was 87° F.), and perhaps from other 
warm bodies of water. This air, as it is drawn up over the mountains 
and plateaus in its northward-moving path, gives up its moisture in the 
common torrential summer rains of that region, strongest near the 
Gulf and fading out in Utah. 

Prediction possibility — If this statement of the possible mechanism 
of our summer rains is correct, it would seem possible to predict their 
amount, some months at least beforehand, by some formula involving 
chiefly the mean temperature of the water in the Gulf of California 
and of the desert areas of the western valleys. 

The Rocky Mountains — The Rockies are high enough to catch the 
westerlies and intercept a remnant of their moisture, and thus they 
partake year by year to some degree in the winter variations which 
come to the Pacific Coast. But in the warmer months the mechanism 
just referred to as acting north from the Gulf of California produces 
a similar effect north from the Gulf of Mexico, and the eastern Rockies 
show a great summer maximum. 

THE THREE ZONES 
Thus, in reference to climatic types, there are three zones lying in 
north-and-south strips delineated by the mountain ranges. On the west 
is the Pacific or Coast zone, where the precipitation is only in winter, 
from the westerly winds coming in off the ocean. The arid interior 
region forms the Arizona zone, whose higher points where the pines 



TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 65 

grow intercept the westerlies and partake strongly in the variations of 
the coast. This zone has a secondary rainy season in midsummer, 
torrential in character and producing for the most part only slight 
effect on the tree-growth. To the east is the Rocky Mountain zone, 
which catches a remnant of the coastal variations and gets its chief 
moisture supply in summer. 

Latitude effect — In each of these zones there is a strong latitude 
effect. On the coast the westerlies are very powerful in the higher 
latitudes, weakening south of San Francisco and becoming gentle at 
San Diego. They disappear entirely in the tropics. In the valleys of 
the central zone the spring rainfall maximum of the north changes to 
the well-defined winter and summer rainy seasons of Arizona. The 
eastern or Rocky Mountain zone has less latitude change than the 
others. The total rainfall increases as we go south by the increasing 
amount of summer rains. In Texas, and still more in Mexico, it 
begins to show a temporary diminished rainfall in July and August 
at the very peak of the maximum. Perhaps this is actually the tropical 
winter minimum of the southern hemisphere reaching over thus far 
into northern latitudes. 

THE PUEBLO AREA 

The Pueblo area trip was made in behalf of the National Geo- 
graphic Society in connection with studies of the Pueblo Bonito 
chronology. It seemed advisable to visit and test the pine and spruce 
regions from which the prehistoric Indians drew their timbers and 
find out whether such regions agree with the Flagstaff areas in their 
tree-growth. 

The Hopi villages — These villages, still occupied, he along the 
southern edge of a raised and sloping plateau called the ''Black 
Mesa," whose surface is dissected by canyons and whose highest 
point, some 75 miles north of the villages, is near Kayenta. 

Kayenta — The 24-hour trip from Flagstaff to Kayenta was made 
on September 4 and 5, 1926. The settlement is in a valley just east 
of Mount Lolomai, the highest point of Black Mesa. Mr. John 
Wetherill, for many years well known in this region, took us to the 
mountain top, 4 miles in a car, 4 or 5 more on horseback, and then a 
climb of 700 feet on foot. Samples collected in several different places 
all show the Flagstaff ring record, as do the rings in the beams of the 
Wetherill house. 

On September 7 we started to Chin-lee, 72 miles southeast, pass- 
ing Chilchinbeto at 16 miles and confirming the agreement between 
Black Mesa and Flagstaff by some specimens there.* At Chin-lee 
we cut radials from logs in the store of Mr. L. H. McSparron, who very 

♦Later, on the return trip, we stopped at Oraibi, the westernmost of the Hopi villages, and 
cut radials from logs of spruce from Pinon, 30 miles northeast, with the same result. 



66 CLIMATIC CYCLES AND TREE-GROWTH 

kindly gave the necessary permission. These logs came from the 
Lukaichukai Mountains east of the Chin-lee Valley, south of the 
Chuskas and north of Fort Defiance and Gallup. A day on horseback 
was spent in the wonderful canyons there, De Chelly and Del Muerto. 
Then we drove southeasterly up onto the Lukaichukai Mountains and 
obtained borings in several places, ending at the sawmill 13 miles 
north of Fort Defiance. These borings and the radials from Chin-lee 
agree with the Flagstaff series. 

We motored southeast to Gallup and then 100 miles northeast 
to Chaco Canyon, and there a most interesting search was made for 
living pines, a number being found at distances of 2 to 20 miles east 
of Pueblo Bonito. These pines, which appear to be a remnant of a 
great forest on those mesas in past ages, also show the Flagstaff series 
of rings. From Chaco our return trip carried us to Gallup, Holbrook, 
and the Petrified Forest, Ream's Canyon, Walpi, Oraibi, Leupp, and 
Flagstaff, 16 days from leaving it. 

Rio Grande Valley — During a trip to the Rio Grande Valley in 
April 1927, specimens of tree-growth from the Zuni Forest, south of 
Grant's, New Mexico, and from the Jemez Mountains, west of Santa 
Fe, were obtained. Each locality shows a perfectly clear Flagstaff 
record. 

Navajo Mountain — By courtesy of Mr. H. Richardson, a trip was 
made in May 1927 to Navajo Mountain, Rainbow Bridge, and Rain- 
bow Lodge. Specimens of Douglas fir from the south slopes of the 
mountain show a perfect Flagstaff record. These recent collections 
therefore leave no further doubt that the whole Pueblo area west of the 
Rio Grande is homogeneous in its tree-growth and forms part of the 
large Flagstaff area. 

SOUTHWESTERN CONTOURS 

The large southwestern arid area is bounded on the west by 
the range of Southern California mountains, including San Antonio, 
10,080 feet, San Bernardino, 11,600 feet, and San Jacinto, 11,000 
feet, which, therefore, form a great rampart impeding the westerly 
winds. East of this range is the Imperial Valley, with the Salton 
Sea some 200 feet below sea-level. The Charleston Mountains form 
an isolated island at the southern point of Nevada. East of the 
Colorado River the land rises to the plateau of northern Arizona, 
while in the southern part of Arizona the land rises to the east 
very gradually, with many "island" mountains high enough to have 
pine trees upon them. The Mogollon Mesa, often called the Rim, 
is the bold and lofty southern edge of the Colorado plateau. It 
cuts across the central part of the State, pointing generally a little 
south of east. South of it are the island mountains; north of 
it the land descends gently to the Little Colorado River and then 



TREE RECORDS! GEOGRAPHICAL DISTRIBUTION 67 

rises gently to the States on the north. On this slope the great 
Black Mesa has large cedar forests, with pines in the canyons and along 
the northern edges. Then to the east is the Chin-lee Valley, and east 
of that, on the border between Arizona and New Mexico, is the range 
called Chuskas on many maps, with a southern part called the Lukai- 
chukais. These carry extensive pine forests. The next pine-covered 
range is a hundred miles east and forms the western boundary of the 
Rio Grande Valley. This range has Mount Taylor at its southern 
end and the Jemez Mountains west of Santa Fe. Chaco Canyon is 
in the large area between the Chuskas and the Jemez Mountains. 
It is surrounded by mesas which probably once held pine forests, but 
the mountains just named are higher and its rainfall is small. East of 
the Rio Grande Valley the big masses of the Rocky Mountains begin. 

WESTERN PINE GROUPS 

Statistics — The whole number of tree records minutely examined 
up to date is about 1,100, and the total number of rings is close to 
210,000. Of these, about 175,000 have been dated and measured. 
The extensive failures to date the coast redwoods are largely responsible 
for this difference between rings examined and rings measured, and 
many of the groups have had a small proportion of the trees which 
could not be dated. The number of trees included in the 42 groups 
whose cycles are studied below is 305 and the number of rings dated 
and measured is 52,400. These trees are practically all western yellow 
pines, with a few Douglas firs here and there. 

Zone statistics — The 42 groups are divided into three zones: 
(1) the interior or Arizona zone, where this study began and has had 
the greatest extension; there are 14 groups in this zone, with 104 
trees and 21,210 measures; (2) the eastern or Rocky Mountain zone 
has 15 groups of 82 trees and 14,135 measures; and (3) the western or 
coast zone has 119 trees in 13 groups, with 17,055 measures. 

Miscellaneous groups — A number of other groups not included 
in the subsequent discussion of cycles follow the western pine groups. 
They consist of groups of different kinds of trees, groups of good trees 
which did not have enough material, such as the Raton and Pecos 
groups of yellow pines with only one record each, of trees which could 
not be dated, such as the coast redwood, and of groups from distant 
localities. 

Group treatment — In the 42 western cycle groups only the individ- 
uals are used which can be dated and also only those parts of each 
individual which can be dated with certainty. In nearly every group 
the curve of each individual tree has been standardized as described 
in a previous chapter. Thus the different trees in a group have equal 
weight and the age effect in the trees is largely removed. 



68 CLIMATIC CYCLES AND TREE-GROWTH 

Analysis — Three analyses were made, namely: (1) the full length 
of the group curve, using maxima; (2) the part of the group curve 
subsequent to 1750 a. d., using maxima; (3) the part of the group 
curve subsequent to 1750 a. d., using minima, that is, plotting an 
inverted curve and then cutting out and analyzing the higher (nega- 
tive) ordinates as usual. 

Precautions — Knowing the possibility of prejudice and systematic 
error in analyzing this large number of curves, several precautions 
were observed: (1) Settings of the White cyclograph were made with- 
out knowing what the reading was going to be; (2) full analysis of 
each curve was made without knowing which curve it was; (3) each 
of the three analyses was carried through the complete list of curves 
in one continuous sitting of four or five hours, so that possible errors 
of adjustment or of judgment would apply equally to all groups; (4) 
the instrument was calibrated from time to time with standard curves, 
and its errors were of the order of one-tenth of a unit of period, which 
is less than the error of an average setting, which is one to three 
tenths of a unit, depending on conditions. Four critical parts of the 
reduction process were invariably done by the writer, namely, dating 
the rings, drawing the standardizing line, marking the cutting line 
for the cycle plot, and making the cycle analysis. Other parts were 
done mostly by assistants, such as mounting, measuring (checked 
afterwards by the writer in most cases), tabulation, plotting, smooth- 
ing, and tracing and cutting the cycle plot. 

Analysis report — A cycle is reported below only when it occurs in 
two of the three analyses, and its relative excellence is shown by a 
number in parentheses following the cycle-length. This number may 
be considered a "weight" and so an approximate amplitude. Unit 
weight, meaning medium or average conspicuousness of the cycle, is 
omitted. Weight 2 means a fine cycle and weight 3 a remarkable 
cycle as viewed in the cyclograph. Cycles occasionally show a lesser 
secondary maximum and very rarely two secondary maxima. In 
such cases the fraction \ or \ respectively, in the parentheses with 
the weight, gives indication of this doubling or tripling. 

Abbreviations — For convenience, the names of the groups are 
sometimes reduced to an abbreviated form which consists of some 
initial letters as suggestive as possible. These letters are given after 
the group title. 

ARIZONA REGION 

FIRST FLAGSTAFF GROUP (FL) 

This group was collected in 1906, 1 or 2 miles west of Woody 
Mountain and some 10 miles southwest of Flagstaff. Nineteen trees 
numbered 7 to 25, were used; Nos. 1 to 6 were not preserved and there- 



TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 69 

fore were not corrected by cross-identification, which was applied 
to the others in 1912. The 19 original sections have been retained and 
two sets of radials have been cut from them; one is the set measured 
in 1906 and cut in 1912 and the other was cut about 1925, so that 
accidental loss of the fragmentary pieces of the original sections would 
do no harm. The curve values as extended to 1910 are given in the 
appendix of Volume I, to which volume reference is also made for the 
curve itself (p. 25) and further details. Measures were by ruler. 
There were so many in this group that for the present purpose it did 
not seem necessary to standardize each tree-curve, as has been done 
in nearly all of the western-pine groups. The smoothed curve shown 
in figure 4 was made by a graphic Hann. The cycles are 6.9 (3), 13.6 
(3), 20.6 (2), and 28.3 (-J-).* It still remains uncertain whether the 
cycle 20.6 years is a real value or whether it is a combination of two, 
of which one is under 20 years and the other about 21 years. 

FLAGSTAFF 500-YEAR GROUP (FLU) 

This group was collected September 10, 1919. Mr. J. F. Freeman 
measured the specimens by the cathetometer method. Long records 
were sought at that time and the two 500-year trees, Nos. 12 and 13 
in the previous Flagstaff series, were completely remeasured and added 
to the five similar trees in this group, Nos. 33, f 34, 35, 37, and 40, and 
a table of seven (unstandardized) trees produced. It is a plot of their 
averages, 1750 to 1917, of which a graphic Hann is shown herewith in 
figure 4. The use of the same two trees in each of these Flagstaff 
groups probably has no real effect on the similarity between the two 
groups, which is very marked, for all these trees give very nearly the 
same record. The cycles found in this group are 14.0 (2), 20.6 (3), 
26.7 (|), 29.1 (|), and 40 (£). The 20.6 varies from 20.2 to 21.0. 
The two near 28 are perhaps variants of one cycle. 

FORT VALLEY GROUP (FV) 

This group is made up of complete sections cut in Fort Valley, 12 
miles northwest of Flagstaff, by Mr. G. A. Pearson, for the purpose of 
studying group effects, or the effect on tree-rings of near neighbors. 
But practically no effect was found unless the neighbor was within 
5 or 10 feet. The trees grew one-quarter mile northeast of the experi- 
ment station, elevation 7,300 feet. Mr. L. R. Patterson measured 
these rings by the auto-plot method. Each tree was standardized. 
The final table and plot were made by Mr. W. G. Austin and the cycle 
plots by Mr. F. M. Douglass. The curve 1686 to 1920, shown from 
1750 in figure 4, resembles FL and FLU and is equally typical of the 

*It will be noted that thia fraction means doubling and not weight. 

fNos. 26 to 32 were cut east of Lake Mary in 1911 and are often called the LM group. They 
are given in the curve on page 27 of Volume I, and as they were only small pieces cut from the 
edge of the stumps, they are not used in this study of western cycles. 



70 



CLIMATIC CYCLES AND TREE-GROWTH 

1800 1850 1900 



' 




/V 


r- 






















1 1 

Flagstaff 1 


ligh level 


ISO 


^ 


Z 1 


V 


A 


A 


/** 


u 
















Upper rim 




• 


■IS 


1/ 








V, 


f 


■\ 


\/V 


y 












Dixie Forest.Utah 
/~K. 




1.75 


\ 




vv 


>/v 


^ 


"W 


■> ; 


/ 


\ 


1 


l n 


n f 


Vv 


/^ 


r^> 


V 


\ 






v~*>. 


V" 




V w 






' 


\/ 


\^ 


\rJ 


V*- 


j\j 


H 


^ 












/ 




























Flagstaff 1 


Jortheast ■ 


2.00 


. 




































2.00 


i / 


^r 


A.«. 




A 














j 




,j 


<\ Grand/ 


iCanyon " 




V 




'\j\ 




v 


^/> 


Vs 


V^ 


f-j 


\j 


^> 


ss/ 


^ 


y 


"^ 


^/ 


M. 






[J 


\ 


V\ 


Aa 


A 


.nr> 


W 


A 


^ 


k/ 


A- 


V 


Flegst 


affKX 


3^ean 


7 


\ 




1.25 


\s 




V 


y 








k/ 




V 


















'.Z5 g 


r 


A 






/\ 








\ 












Early Flagstaff ■ 


9 
*3 


V s 




v\ 


A 


AV 


r^ 


\a 


/ 


w 


W 










^~ 


^M" 






■g 




fK 


1 


,* 


A, 






f\ 


A, 




J\ 


J 


Fo 

1 


-tval 
/ 




7 


k 




,50 | 

■ 


J 




\ 


,/ 


V 


j •* 


V 


J 




u 


* L. 


'V 


A 


^ 






i 




1.00 -g 

o 


■ 




n 




/v 






r 


\\ 


k«i, 


/\ 


J 


Flagstaff shadow I 


W 


y 


00 

a 
1 


f 


^ 


V 


A- 


' 


k/ 


V 


J 




V 


\ 


r> 


Vv 




Low 


erRin 
n 




\ 


1.25 « 


■ 




M 


M 


/\ 






p 


nj 






( 




ft/ 


\_ 


/ 


V 




1.50 


■ 


r\ 


\ 


J 


A 


>/ 


*1 


J 


u 


V 


\ 


J 

f 


In 


/ 


C 


1/ 

ibecue 






1.50 


V 


J 


\ 


J* 


l\ 


^ 


^ 


/* 


rJ 


^ 


/T 


4 


W 


y^ 


V 


i 


^ 






■ 


X 


\ 




. / 


"~v 




r 


X 


yv 


I 


\P 


p 


nal Mc 
nr,, 


untains / 






1.25 


■ 




W- 


y n 


v^/ 




^N 


j 








V 


U^ 


^J 


\J\J 


^ 






■ 










/ 


>A 


/\ 














Santa Rita Mountains 


1.50 












H 


\ 


r 


\J 


n 


A 


\ 




r\ 


r 


^ 


-,^— 






j 




V 


W 


/u/ 1 


/ 


\ 


/ 


\J 


% 


; 


W 


^r 


'V 


J 


u/ 




- ■ 






/v 


y^ 


^ 


fl> 


l/* 


^ 


/■ 


s f 


A 


1 . 




r 


l/^ 


Ca 


_alina 


Wounb 


ItiTS 


150 


/' 






V 


/ V 




l 


y 


V 




V 


V 


^ 


<s \s- 













1800 1850 

Fig. 4 — Arizona zone, smoothed 



1900 1930 

group curves 



TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 71 

central Arizona area. It shows cycles as follows: 13.1, 14.5, 18.5, 
20.5 (3), and 35 (3, J). The 13.1 and 14.5 are very possibly variants 
of one about 14 years. The 20.5 again varies from 20.0 to 21.0. 

HIGH LEVEL GROUP (FLH) 

The idea of testing the effect of altitude on the ring-growth was 
held from an early date. The first actual collection for it was done on 
June 19, 1920, when Dr. E. J. Brown and the writer went on foot up 
the canyon above Shultz Pass, where the Weatherford Boulevard has 
recently been constructed. But the specimens were crudely cut and it 
was felt that it would be preferable to test tree-growth on the west or 
southwest slope of the mountain. Accordingly, on July 11, 1920, a 
trip was made up the southwestern ridge of the mountain from the 
southern end of Hart Prairie to the cabin used by the experiment 
station at an elevation of 10,500 feet. Director Pearson and Mr. Haasis 
of the staff were of the greatest assistance. A very interesting group, 
numbered Fl 69 to 80, was obtained, including Douglas fir, cork-bark 
fir, Umber pine, fox-tail pine, and Engelmann spruce. But this seemed 
to combine too many different species over too great a range of alti- 
tude; accordingly, the group of yellow pine increment-cores here used 
was collected with the aid of Mr. Pearson on July 12, 1924, at eleva- 
tions averaging a little under 9,000 feet, that is, really in two sub- 
groups, one at the south end of Hart Prairie and the other at a little 
over 9,000 feet altitude. 

These 10 cores were measured by Mr. D. A. Hawkins, using the 
long-plot (longitudinal plot) method, and were then tabulated and 
averaged and the curve, 1770 to 1923, plotted without standardizing. 
A graphic Hann, shown in figure 4, was made by Mr. F. M. Douglass. 
In general appearance this smoothed curve has all its variations greatly 
diminished and is otherwise somewhat discordant compared to the 
usual Flagstaff tree-records. It introduces a 17-year cycle, which is 
not common in this region; but its cycles belong to the Arizona class 
and are as follows: 6.9 (2), 9.1 (oc. £), 13.7 (2, -J), 17.3 (3), 20.5 
(2, oc. i), 27 (oc. i), and 35 (2, oc. £). 

FLAGSTAFF SHADOW GROUP (SH) 

The old-time winter road to all points north of Flagstaff passed 
east of the San Francisco Mountains because it was drier, warmer, 
and had less snow than the west side. The forest regions east and 
northeast of the peaks are shaded by the mountains from the wet 
westerly winds, and the special effect observed in this group and 
others is called the shadow effect. This group of five Swedish incre- 
ment-cores was collected on July 13, 1924, in a specially selected area 
nearly on a fine between Sunset Crater and the peaks, and about half a 
mile west of the main highway. At this place the elevation is very 

6 



72 CLIMATIC CYCLES AND TREE-GROWTH 

little above that of Flagstaff and is about the same as that of the Fort 
Valley group, with which the curve, therefore, can be compared for the 
shadow effect. Mr. Hawkins measured these specimens by the long- 
plot method and, without standardizing, plotted a curve from the 
averages. This curve, 1717 to 1923, was Hanned mathematically and 
the cycle plot was made by him also. This smoothed curve from 1750 
on is shown in figure 4. The great variation between maxima and 
minima is at once apparent and is characteristic of lower and drier 
altitudes. The shadow effect does not appear to differ much from 
simple reduction in rainfall, equaling in this case the effect of about 
1,500 feet change of altitude. The spacing of the maxima is strongly 
of the Flagstaff or Arizona type. The observed cycles are 14.1 (3), 
19.4 (2), 27.3 (2, -J) and 40 (2, oc. £). 

FLAGSTAFF NORTHEAST GROUP (NE) 
This group was collected on June 14, 1923, in connection with 
prehistoric dating problems, to determine with certainty whether the 
part of the Flagstaff forest area nearest the prehistoric ruins carries 
the same ring records as the very old trees just south of town. Dr. 
E. S. Miller, of Flagstaff, was kind enough to take me out 19 miles on 
the Tuba road and there, at the edge of the forest, I took four incre- 
ment-borings. Mr. Hawkins measured these in 1923 by the auto-plot 
method. These were thoroughly rechecked by the writer (as in all 
cases). These individuals were so nearly alike in average growth that 
they needed no further standardizing. The curve, 1678 to 1922, 
identifies exactly with the Flagstaff record. It was smoothed by 
graphic Hann by Mr. Austin and the part from 1750 on is shown in 
figure 4. The cycle plot analyzes as follows: 8.5, 11.6 (2), 14.3 (2, 
oc. £), 19.4 (2), 27.7 and 36 (2); these classify as Arizona type, though 
the 11.6 is not so common as on the coast. 

GRAND CANYON GROUP (GC) 
The edge of the Grand Canyon is 65 miles north and a little west 
of Flagstaff. Leaving the San Francisco Peaks and traveling north, 
one descends gradually for a time away from the pines, down through 
the cedars, across a barren area, then up gradually through the cedars 
and into the pines which border the canyon. Much of the forest area 
near the canyon is perfectly flat. The Grand Canyon group was taken 
in early July 1920, at points scattered several miles along the south 
rim from a little west of Grand View to the Buggeln property, which 
used to be Tolfree's Hotel, at the top of the old historic Hance Trail, 
a distance of 5 or 6 miles. The soil here is a thin layer of earth over 
limestone. There appears to be very little surface drainage and it is 
probable that the water soaks down through the limestone formation 
and emerges in springs in the canyon. In the early days, Tolfree 's got 
its drinking-water from artificial "tanks" or pools of standing water 



TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 73 

formed from the melting winter snow. Mr. Patterson measured 7 of 
this group of eight v-cuts by the auto-plot method in 1922. Each 
tree record was later standardized, tabulated, and plotted by Mr. 
Austin in a curve from 1716 to 1919. This curve is of perfect Flagstaff 
type. The graphic Hann shown in figure 4 was made by Mr. F. M. 
Douglass in 1926. The cycles belong to the Arizona classification, as 
follows: 11.7, 14.5, 18.4, 20.8 (2), 23, and 36 (oc. ■§•). 

DIXIE FOREST (UTAH) GROUP (DF) 

This is a group of Swedish increment-cores collected and sent me 
by Mr. William M. Mace, supervisor of the Dixie National Forest, 
from the Pine Valley Mountains, in the southwestern corner of Utah. 
As in the case of the Charleston Peak of southern Nevada, it seemed 
desirable to find some groups intermediate in position between the 
Flagstaff area and the region of the big trees of California. Mr. Mace 
writes that these specimens came from the westerly side of the moun- 
tains at an elevation of 8,500 feet. This would seem to correspond 
in topography to group FLH, but their record, though very complacent 
like FLH, resembles FL more than FLH does. The cores were received 
October 1, 1923. Mr. Austin measured them by the long-plot method 
in 1926. Each tree was standardized and the table and averages and 
plot were also made by Mr. Austin. The curve extends from 1616 to 
1922 and shows good resemblance to the Flagstaff curve. It was 
smoothed by graphic Hann and is thus shown from 1750 in figure 4. 
Its cycles are of the Arizona type, as follows: 19.6 (3), 27.1, and 40 
(2, oc. i). 

UPPER RIM GROUP (RH) 

Next to the Grand Canyon, Arizona's most remarkable scenic 
feature, on a large scale, is the Rim. This is the abrupt southern edge 
of the great Colorado Plateau. It is an ancient fault-line; the rocks 
to the north average 7,000 feet above sea-level and 1,000 to 2,000 feet 
higher than those to the south, with other steep slopes below, so that 
from the Rim one looks over enormous stretches of Southern Arizona 
with its island mountains showing faintly in the blue haze of distance. 
The edge of the Rim stretches across half of the State in a generally 
uniform direction, but is wavy or zigzag in detail. So, when seen from 
below, for example, from near Pine or the Natural Bridge, its sinuous 
length extending easterly as far as the eye can see, could be classed 
as one of the wonders of the world. 

An extraordinarily large and pure pine forest covers this Rim and the 
adjoining slopes, connecting on the north with the Flagstaff area and 
extending on the east past the White Mountains and into New Mexico.* 

♦Years ago, by kindness of Mr. F. S. Breen, then supervisor of the recently created national 
forest, it was my privilege to traverse this Rim from Camp Verde to Nutrioso, close to the New 
Mexican border, in a buckboard. I have no doubt that 600-mile trip from Flagstaff, lasting 26 
days, helped to originate this investigation of the history recorded in tree-rings. 



74 CLIMATIC CYCLES AND TREE-GROWTH 

Thus the bold, pine-covered headlands of rock overlooking southern 
Arizona differ in topography from the Flagstaff region, and it seemed 
worth while to get a group of borings in such a locality. This was 
easily done in a motor trip from Tucson to Flagstaff, on which I was 
assisted by Mr. T. J. Randolph. The borings were made on August 
26, 1922, two of them at 6,000 feet elevation, near the fork in the 
highway between Pine and Strawberry, where the road to Flagstaff 
starts up the big grade. These were numbered 91 and 92 in the Flag- 
staff series and form the group RL. Two other borings were made 
at the top of the Rim, where the elevation is 7,000 feet. These were 
numbered 93 and 94 and constitute the present group RH. It was 
intended to include all of these four in one group, but the two locations 
proved so different in their effect on ring-type that it was thought 
best to separate the pairs. The individuals of each pair agree finely. 
Mr. Hawkins measured these four cores by auto-plot method. They 
were then completely rechecked by the writer and individually stand- 
ardized. The tables and curves were done by Mr. Austin. The curve 
of the Upper Rim group, 1697 to 1921, smoothed by graphic Hann, 
and shown in part in figure 4, is very complacent, and has only moder- 
ate similarity to the typical Flagstaff curve. Its cycles, however, 
keep it in the Arizona zone, for they are as follows: 14.7, 19.9 (3), 
and 37 (2). 

LOWER RIM GROUP (RL) 

This group, as described in connection with the preceding, con- 
sists of two increment-cores collected August 26, 1922, near the fork 
in the road at the foot of the long Strawberry grade. The eleva- 
tion is 6,000 feet. Its location is a south exposure with the great 
thousand-foot wall of the Rim immediately to the north and a low, 
flaMopped mesa "island" close to the south, standing up a few 
hundred feet. The curve, 1770 to 1921, smoothed by a graphic Hann, 
is shown in figure 4. Its striking variations resemble a shadow effect 
like that in the SH group, which it minutely resembles. In fact, the 
remarkable likeness between this curve and those of FLU, FV, SH, NE, 
GC, and J groups puts this collection of groups in a distinctive homo- 
geneous class whose locus extends at least from the Grand Canyon to the 
Rim, a distance of about 150 miles. The RL cycles are 10.1, 12, 20.1 
(3), 23.7, 27.6, and 38 (2, oc. -J). The absence of 14 years makes it 
resemble the cycle of the Rocky Mountain zone, but as 14.4 did appear 
in good form in one of the three analyses, its place in the Arizona zone 

is justified. 

CIBECUE GROUP (J) 

The Cibecue group of five increment-borings was collected on 
July 23 and 24, 1920. The area included in this group extends from 
the store on Grasshopper Creek (15 miles west of Cibecue Creek store) 
to the small creek about a mile east. This is some 20 miles south of 



TREE RECORDS! GEOGRAPHICAL DISTRIBUTION 75 

the Rim and about halfway between Pine and Fort Apache. The 
elevation is under 6,000 feet. The region is reached by motor from the 
White River Indian School near Fort Apache. The cores were meas- 
ured by Mr. Patterson, using the auto-plot method, and fully re- 
checked. The curve, 1652 to 1919, was plotted directly from the 
averages and cross-identifies closely with the Flagstaff record. The 
graphic Hann from 1750 on is shown in figure 4. It resembles RL 
strongly. The cycles are 8.2, 9.6, 12.1, 18.5, 23.8 (3), and 30.5. There 
was no sign of a 14-year cycle, and therein it resembles the Rocky 
Mountain curves. 

PINAL MOUNTAIN GROUP (PNL) 

Surrounded by the lower levels of southern Arizona, the Pinal 
Mountains form an island 90 miles from the Rim groups described 
above. To reach them from that part of the Rim, one motors down 
Tonto Creek and after leaving Four Peaks on the right, passes Roose- 
velt Lake and Dam. Twenty-five miles beyond are the cities of 
Globe and Miami, south and west of which are the Pinal Mountains. 
A road goes to Tucson over each flank. To the east is the Winkelman 
road ascending almost to the pine level; to the west is the Globe- 
Superior Highway, a splendid bit of road engineering over a rocky and 
picturesque table-land. Four borings were made September 5, 1924, 
above the camp-grounds, southwest of the main peak. These cores 
were measured by Mr. Swan Erickson, using the long-plot method. 
Each tree of the three usable ones was standardized and the resulting 
curve (see fig. 4) shows distinct resemblance to the Flagstaff curve — 
more in fact than do the curves of the other island mountains. The 
cycles are 7.6 (2), 10.1, 14 (oc. •£•), 23, and 27. This grouping of cycles 
is classed as general, since it is rather deficient in the special charac- 
teristics of each zone. 

CATALINA MOUNTAIN GROUP (SC) 

The Catalinas are about 60 miles a little west of south from the 
Pinals. They are a large, rambling mountain mass without distinctive 
top and form an emphatic northern boundary to the Tucson Valley. 
The main summit, Mount Lemmon, elevation 9,150 feet, has an 
inconspicuous rounded top with a fire lookout. Close on its southeast 
edge is the resort, Summerhaven, with an easterly ridge extending 
4 or 5 miles to Bigelow Peak and beyond. Central on this ridge is the 
beautiful little valley known as Bear Wallow, with the ranger station 
and Soldiers' Camp. The SC group consists of eight increment-cores 
and one 350-year v-cut, all usable except one core. Their location 
extends from Summerhaven to Mount Bigelow. Some are on the very 
crest of the ridge and some are a hundred feet or so lower down on the 
south side. The average elevation is about 7,500 feet. The contours 



76 CLIMATIC CYCLES AND TREE-GROWTH 

are given in some detail, because this group, while internally very- 
satisfactory, is as a whole the most discordant in the entire Arizona 
area, both in cross-identification of rings and in comparison between 
smoothed curves. The SC specimens were measured part by auto- 
plot and part by long-plot method. Individual trees were standard- 
ized. The final curve, 1567 to 1919, shows a very limited resemblance 
to curves in the Flagstaff area. After being smoothed by graphic 
Hann, it shows many reversals of Flagstaff growth, for example, the 
years near 1630, 1670, 1730, 1847, and 1880 have big growth instead of 
small. The part since 1750 is given in figure 4. The cycles are 7.5, 
9.2 (oc. £), 11.3, 17.4 (2), 22.9, and 34.7 (3, oc. £). The presence 
of 11.3 and 17.4 gives it a resemblance to the Rocky Mountain zone 
which incidentally has a number of reversals compared to Arizona. 

SANTA RITA GROUP (SR) 

The Santa Ritas, 9,400 feet in elevation, are 50 miles due south of 
the Catalinas and form a massive mountain boundary on the east 
side of the Santa Cruz Valley south of Tucson. The mountain slopes 
are steep and the summit itself forms an upstanding monument of 
rock 500 feet high, very striking in appearance. The pines cover the 
upper parts of the mountain, but favor the north-facing canyons 
where the snow lingers. Some Mexican species of pine are found here, 
but they closely resemble the western yellow pine. A group of 10 
borings was collected in the upper parts of White House Canyon, the 
summer-resort region, on May 2, 1921, but these could not be dated, 
as the doubling of rings by the pronounced summer rains made the 
annual character very uncertain, a summer condition much more 
pronounced here than in northern Arizona. So a second group of 6 
borings was made December 22, 1921, at higher levels, that is, from 
7,500 to 8,700 feet, of which all but one were usable. In this collection 
I was assisted by Mr. M. S. Lankford. In a recent review it was 
noted that the Santa Rita tree-records have the intensely small 
Flagstaff years, 1847, 1902, 1904, and so forth, but are erratic within 
the group, omissions and change of size making cross-identification 
very laborious. 

Each of the five trees was standardized and the resulting average 
curve, 1670 to 1921, smoothed by a graphic Hann, as shown from 1750 
in figure 4. It resembles both the Flagstaff and the Catalina records. 
Its minute details confirm the dating of the Catalina specimens, which 
were at first held in considerable doubt. The cycles are 7.5, 11.2, 
14.4 (3, oc. $), 23.0 (3), and 27.4 (oc. £). This is distinctly of the 
Coast type. On the whole, it will not be surprising if these southern 
island mountains are influenced by some climatic situation distinctly 
different from the northern Arizona plateau area. 



TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 77 

THE ROCKY MOUNTAIN ZONE 

YELLOWSTONE GROUP (Y) 

This group of five increment-cores of white-barked pine (Pinus 
albicaulis) was collected on August 20, 1920, at the eastern edge of the 
flat top of Specimen Ridge, west of and opposite the buffalo farm, in 
northeast Yellowstone Park. The trip was made from Camp Roose- 
velt with the assistance of Mr. A. G. Whitney. The specimens were 
cross-identified and dated in 1926. They were measured by Mr. 
Austin, using the long-plot method. They were standardized and 
give a record from 1693 to 1919. The curve from 1750, smoothed as 
usual, and shown herewith in figure 5, does not closely resemble the 
other Rocky Mountains curves, though its cycles are distinctly of that 
type. They are 8.5 (3), 10.4, 12.5, 17.1 (3, oc. J), 25.6, 30.3 (oc. £). 
Here we see the 17-year period which is characteristic of this eastern 
zone. 

LARAMIE. WYOMING, GROUP (LW) 

This group of four cores, of which three only could be dated, was 
collected on June 11, 1925, while motoring from Fort Collins, Colorado, 
to Laramie, Wyoming. At some point not far from the State border 
the road passes through a slight ravine with pine trees on the steep 
slopes. The three cores afterwards used were obtained here. A few 
miles farther on, a very large pine growing in a bleak flat area was 
bored, but the outer rings were too small for certain dating. These 
specimens were measured by Mr. Austin, using the long-plot method. 
The records were each standardized and the curve, 1754 to 1924, was 
smoothed by graphic Hann, which is shown in figure 5. Though its 
variations are immense, it closely resembles the typical Pike's Peak 
curve. Its cycles present the characteristic 17-year period with what 
are probably some of its variants. The cycles are: 6.3 (2), 8.2 (3), 
11.5 (oc. i), 15.9 (oc. £), 17.4, 18.2, 19.1 (oc. $), 25.0 (oc. J), and 
35 (2). 

CLEMENTS'S PIKE'S PEAK GROUP (C) 

In 1919, Dr. F. E. Clements initiated this study of the Rocky 
Mountain zone by sending me nine sections of trees from the vicinity 
of the Alpine Laboratory, which is just south of the Cog Railroad 
above Manitou, at an elevation of 8,700 feet. He described the 
location of these trees as follows: Three yellow pines from north of 
track with a south exposure, three Douglas firs from above cabins 
with a northerly exposure, and three Engelmann spruce from near the 
brook, with a northeasterly exposure. These were actually cut and 
packed by Mr. C. W. Cherry, who later helped me at Tucson for a few 
months. One of the pines was defective and could not be used, and 
the remaining eight trees were averaged and plotted in a curve from 
1783 to 1919. This was recently Hanned graphically, as shown in 



78 



CLIMATIC CYCLES AND TREE-GROWTH 

1800 1850 




1750 1800 1850 1900 1930 

Fio. 6 — Rocky Mountain zone, smoothed group curves 



TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 79 

figure 5, and gave as cycles: 9.3 (2), 18.8 (2, ■£■), and 34.8. So much 
material was obtained subsequently from that area that this group, 
with its informal treatment, has been retained as a check on the 
others. Without doubt the Douglas firs could be included with the 
yellow pines, but the Engelmann spruces should be kept separate. 
This will appear in the Brook group of Engelmann spruce (BES) . 

PIKE'S PEAK TIMBERLINE GROUP (PPT) 

The first Pike's Peak group was obtained close to the Cog Road 

near timberline, at an approximate elevation of 11,500 feet. Naturally, 

the trees were not yellow pine. No. 1, a chip from a dead tree, had 

to be discarded, but five increment-cores, two in Engelmann spruce 

and three in fox- tail pine (Pinus aristata), proved good specimens. 

They were readily dated and were measured by Mr. Austin by the 

long-plot method. Each tree record was standardized and the curve, 

1734 to 1919, was smoothed in the usual way. The portion since 

1750 is given in figure 5. Its complacent character shows at once, 

yet it compares exceedingly well with the smoothed curves of groups 

3,000 feet lower down the mountain. The cycles are 11.7, 14.0, 20.0, 

22.6 (oc. J- or -J), and 37. This group, therefore, does not classify 

well as of Rocky Mountain type, but its cycles are of the general 

western sort. One notes here the tendency of the double sunspot cycle 

to fall a little below 23.0 years; in the Arizona area it was usually a 

little above. 

PIKE'S PEAK BASIN GROUP (PPB) 

In making its way east after passing timberline, the Cog Road 
descends sharply into and then more gradually through a basin area 
to an outlet in Ruxton Creek, where the water-supply for the cities 
below is taken. The more level part of the basin has an altitude of 
about 9,500 feet, and here four borings were taken, of which three 
(PP 7 to 9) form the basin group. Mr. Austin measured these by the 
long-plot method. After standardizing, a curve, 1693 to 1919, was 
drawn and smoothed by graphic Hann; figure 5 gives the part since 
1750. This has much larger variations than the timberline group and 
compares closely with the later groups near the Alpine Laboratory. 
The unusual feature in this group is the doubling of average growth 
after 1865. The cycles are 10.2 (2), 13.0 (oc. |), 20.0 (3, £), 25.6, 
and 30.7 (2, oc. ^ or £). The absence of a 17-year cycle is not 
usual in this zone, but the presence of 25- and 30-year cycles is very 
characteristic. 

UPPER NORTH TRANSECT GROUP (HNT) 

The Alpine Laboratory has an elevation of about 8,700 feet, and 
near it are varying contours well worth testing. The various Pike's 
Peak groups, including those already described, were originally 
selected as a study in topography. After leaving the basin the Cog 



80 CLIMATIC CYCLES AND TREE-GROWTH 

Road descends sharply, following the bed of Ruxton Creek. The 
laboratory is situated on a small southern tributary, Jack Creek, 
just above their confluence. Dr. Clements has made extended ecologi- 
cal studies on a certain area, the Transect, which extends a half mile 
up the high, wooded slopes to the north and perhaps a third of a mile 
up the shorter and more barren slopes to the south. The north branch 
of this transect has very steep slopes in the lower part near this creek 
and the Cog Road, and gentler slopes above. So the collections there 
were divided into upper and lower groups. The upper group, PP 
11 to 20, has an average altitude of over 9,000 feet and includes 5 yellow 
pines, 3 Douglas firs, and 2 limber pines. These 10 cores were meas- 
ured by Mr. Austin, using the long-plot method. They were stand- 
ardized, and the curve, 1655 to 1919, was smoothed as usual, and the 
part since 1750 is shown in figure 5. It resembles the neighboring 
groups very closely indeed. Its cycles are 6.8 (2), 8.6 (2), 9.3, 13, 
17.2, 22.6 (2), and 34.5 (2, oc. £). 

LOWER NORTH TRANSECT GROUP (LNT) 

The lower group, PP 21 to 27, in the North Transect, was 250 feet 
below the upper, estimated in vertical height, which makes it about 
8,800 feet above sea-level. Mr. Austin measured these cores also by 
the long-plot method, and the curve, 1644 to 1919, smoothed after 
standardizing, is shown (after 1750) in figure 5. The result shows a 
rather even curve, more complacent than the trees farther from the 
brook. It compares closely with the other group curves. Its cycles 
are 11.1 (2), 16.0, 20.4 (2), 21.3 (oc. -£), and 40, which approximate 
but are not exact in their conformity to the Rocky Mountain cycles. 

SOUTH TRANSECT GROUP (ST) 

South of the Alpine Laboratory the slopes rise abruptly up to 
some very barren sand areas on Baseball Ridge. A collection of 10 
increment-borings was made here with the help of Dr. Gorm Loftfield 
at an average level perhaps of 8,900 feet. Two of these are yellow 
pine, 6 are Douglas fir, and 2 are limber pine {Pinus flexilis) . They 
cross-identified well and were measured by Mr. Austin and stand- 
ardized. The curve 1570 to 1919 was smoothed as usual and the result 
(since 1750) is given in figure 5. It shows vigorous variations which 
make it probably the best representative curve of this Pike's Peak 
area. Its cycles also are entirely typical of the Rocky Mountain 
zone; 9.8 (2), 17.2 (2), 19.7 (3, oc. \), 25.2 (2), 31.1, and 34 (oc. $). 

BROOK GROUP OF DOUGLAS FIR (BDF) 
Ten trees were tested along Ruxton Creek near the Alpine Lab- 
oratory, with the purpose of forming a brook group and of learning 
whether the Engelmann spruce reacts to abundant ground-water in the 



TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 81 

same way as the yellow pine and Douglas fir. While dating the records, 
it was evident that the Engelmann spruce was giving a different 
story and could not be joined with the firs and pines. So the brook 
trees are separated into two groups, of which this one is made up of 
4 firs and 2 yellow pines. One of these firs, PP-35, carries a dendro- 
graph designed by Dr. D. T. MacDougal. The two yellow pines are 
only a few feet away, and these three trees are sometimes referred to 
as the dendrograph group; but they are themselves close to the brook 
and their records agree well with the other Douglas firs near by, so 
they make up part of this group. These six cores were measured by 
Mr. Austin, using the long-plot method, and after standardizing gave 
a curve from 1782 to 1919, which was smoothed in the usual way and 
is shown in figure 5. This closely agrees with the other adjacent 
groups already described, and with them (PPB, HNT, LNT, ST, and 
C) forms a collection of homogeneous groups which must represent 
this region exceedingly well. The cycles of the Douglas fir brook 
group are 7.5, 9.5 (2), 11.4 (oc. £), 14.3 (oc. £), 20 - 4 ( 2 )> 22 -5 ( 2 , 
oc. ■£), and 39, a good Rocky Mountain set. 

BROOK GROUP OF ENGELMANN SPRUCE (BES) 

Engelmann spruce growth on the San Francisco Peaks in Arizona 
had been too complacent for use in climatic study, but on Pike's Peak 
four trees, PP 28 to 31, along Ruxton Brook, showed attractive 
variations and even exhibited weak signs of cross-identification 
among themselves. But when the curves were drawn, it was seen 
that their growth does not match the growth of the other brook 
species. The cores were measured by Mr. Austin by the long-plot 
method and standardizing lines marked on each individual tree-curve 
by the writer, as always. The resulting smoothed curve, from 1775 
to 1919, shown in figure 5, presents marked variations, departing 
greatly from the typical Pike's Peak curve. Its cycles are 8.9 (2), 
12.2 (2), 14.1 (2), 17.6 (£), 24.7 (oc. £), and 34 (oc. •£). The 17- 
year cycle is characteristic of the Rocky Mountains, but the presence 
of a 14-year cycle and a probable sunspot cycle make this set resemble 
the cycles of the Coast zone. 

CLOUDCROFT. NEW MEXICO. GROUP (CC) 

Any real representation of the Southwest would be incomplete 
without specimens from New Mexico's summer resort, Cloudcroft, in 
the Lincoln National Forest. Accordingly, six good v-cuts from pine 
stumps were sent me by Mr. Dan Felts, forest ranger there. Three 
only could be used, and these, as Mr. Felts writes, come from the 
northwest quarter of the southeast quarter of section 23, township 
16 South, range 11 east, New Mexico prime meridian. This is the 
extreme upper end of Nelson Canyon watershed, half a mile west and 



82 CLIMATIC CYCLES AND TREE-GROWTH 

southwest of Russia, New Mexico. Mr. C. W. Cherry measured 
these specimens by auto-plot method. They were approximately 
standardized by assigning added weight to the slower-growing trees 
in forming the averages. The resulting curve from 1736 to 1920, 
smoothed by a careful geometric Harm and mostly shown in figure 5, 
presents strong variations which have much in common with the 
Pike's Peak curves. The cycles are 11.2 (oc. £), 13-4, 15.3 (2), 17.8, 
22.1 (i or i), 27.5 (i), and 36 (i). 

SANTA FE GROUP (SF) 

This group was collected on September 5, 1922, with the aid of Mr. 
B. Z. McCullough, who took me some 4 or 5 miles up the canyon 
east of Santa Fe, New Mexico. The trees selected had usually a 
north exposure and were in the general vicinity of the ranger station. 
They were chosen at considerable height above the brook, so as not 
to be influenced by it. All of the six cores were readily dated by 
resemblance to the Flagstaff series. Mr. C. W. Cherry measured 
these rings by the auto-plot method. After standardizing, he plotted 
their average in a curve from 1749 to 1921 and smoothed it by a careful 
geometric Hann. The result given in figure 5 shows excellent varia- 
tions with distinct apparent similarity to curves of the Flagstaff area, 
but the cycles conform more to the Rocky Mountain zone, being 
10.2, 11.9, 18.4 (2), 22.4, 27.5, and 35 (2, oc. $). The absence of a 
14-year period places it with the Rocky Mountain groups, although 
the absence of the 17-year period is unusual in that zone. 

BASIN MOUNTAIN UPPER GROUP (BMH) 

The collection of this and the two following groups is due to the 
cooperation of the archaeologists. In August 1919 I visited the Aztec 
ruins, New Mexico; thence Mr. Morris took me to Sullivan's saw- 
mill on Basin Mountain, in Colorado, nearly 40 miles north of Aztec 
and perhaps 15 southwest of Durango. The mountain has a per- 
fectly flat top about a mile across, covered with pines. The saw-mill 
is 2 or 3 miles away, in the basin to the east. The pine trees extend 
down to the mill and a few scattered ones are found even lower 
down. Two v-cuts were taken from logs at the mill; five more were 
cut from stumps on the mountain-top before it got dark, and on the 
way down we cut the three which made the lower group, of which 
the last was cut by the light of matches long after nightfall. This 
division into upper and lower groups was made on account of varying 
water-supply in the soil. The date was August 13, 1919. Mr. J. F. 
Freeman measured all these specimens by the standard cathetometer 
method and the seven from the mountain- top have been combined 
without standardizing to form a curve beginning 1588 and ending 
1919, which cross-identifies minutely with the Flagstaff tree-growth. 



TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 83 

This curve, smoothed and shown in part in figure 5, distinctly re- 
sembles the Flagstaff curves in position of the more prominent maxima, 
but its cycles, 8.5, 16.8, and 35 (2), are characteristic of the Rocky 
Mountain zone. 

BASIN MOUNTAIN LOWER GROUP (BML) 

The three v-cuts in this group were collected August 13, 1919, as 
has been described in the preceding paragraph. Their actual loca- 
tion was on the upper easterly slopes of Basin Mountain, some 500 
feet vertically below the top. Thus climatically they are in the same 
situation as the others, but with regard to soil moisture they are very 
different, for they catch a local drainage. In fact, the lowest of the 
three, No. H-29, had large complacent rings and could not be used. 
The two remaining ones average 50 per cent larger growth than the 
upper group. Mr. Freeman measured these with the cathetometer. 
The curve, not standardized, begins at 1700 and ends 1918. The 
smoothed curve from 1750 is shown in figure 5. The cycles are 10.5, 
11.6, 13.4, 20.4 (oc. i), 22.7 (3), and 37, which resemble the Coast 
cycles. 

AZTEC EAST GROUP (AE) 

On inquiry, Mr. E. H. Morris found that there were Douglas 
fir trees nearer Aztec than the pines of Basin Mountain, namely, at a 
point some 20 miles east. Accordingly, early in 1920 he secured four 
specimens from there, H 39 to 42, which form this group. They showed 
severe drought effects in several places, which made the dating of the 
central parts uncertain, and accordingly later in the same year he 
sent me five more, H 65 to 69, which gave entire certainty to the 
dating. The earlier four were then measured by Mr. Freeman with a 
micrometer slide, and the curve, 1662 to 1919, drawn without standard- 
izing (as was the case with several of the early curves) and smoothed, 
is «hown in part in figure 5. As with the others from this region, it 
resembles the Flagstaff curves. Its cycles are 8.1, 12.4, 19.5, 24.0 (3), 
and 34.2 (oc. ^-), which resemble both the Flagstaff and the Rocky 
Mountain cycles. A later curve, using all these "Modern H" trees, 
gives cycles as follows: 8.2, 13.7, 18.8, 20±, 23.8, and 36. 

THE COAST ZONE 

BOISE, IDAHO, GROUP (BI) 

This group is a set of 10 increment-cores sent by the forest super- 
visor of the Boise National Forest, in July 1923. They came from 
the southwestern parts of the forested mountains, some 50 miles 
northwest of the city. The growth is complacent, but the cross- 
identification of all 10 is good. Two of the trees cross-identify with 
some of the trees from Klamath Falls, in southern Oregon. These 



84 



CLIMATIC CYCLES AND TREE-GROWTH 



rings were measured by Mr. Austin, using the long-plot method, 
and represented dates from 1652 to 1922. The smoothed curve, 




1800 1850 

Fig. 6 — Coast zone, smoothed group curves 



shown in part in figure 6 herewith, when taken in its entire length, and 
especially when reduced to 3 specimens showing more variation, though 
complacent for short cycles, evidently has a long period of the order 



TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 85 

of 40 years. The cycles are 6.4, 11.6 (3, oc. £), 17.2 (oc. £ or J), 23.0 

(oc. \ or -J-), and 36. This strong emphasis on the single sunspot 

cycle, especially in the higher latitudes, is very characteristic of the 

Coast cycles. 

BAKER, OREGON. GROUP (BO) 

The higher parts of the pass between Baker, Oregon, and the 
Columbia River are pine-covered, and at distances from Baker vary- 
ing between 60 and 90 miles 8 increment-cores were obtained. 
These are complacent, and the dating, though probably right, has 
not the certainty of the Arizona and Rocky Mountain pines. One 
core had to be omitted because it was erratic, probably from injury. 
There was some cross-identification with the Boise and the Klamath 
Falls groups. The rings were measured by Mr. Austin, using the long- 
plot method. The records were standardized and a curve produced 
extending from 1660 to 1924. This was smoothed by the usual graphic 
Hann and is shown in part in figure 6. It is a trifle less complacent 
than the Boise group and, like it, tends to show a long period of the 
order of 40 years. The cycles are 6.8, 9.1, 11.3 (2, oc. £), 15.0, 21.8 
(2, oc. %), and 28.4 (oc. -J). These have some of the Rocky Mountain 
characteristics. 

DALLES GROUP (DL) 

The most beautiful part of the Columbia River Highway passes 
through the mountain range between Portland and The Dalles. On 
the west side of this range the rainfall is heavy and the vegetation 
profuse; the east side of the mountains is dry, looking out onto the 
arid areas of central Oregon. A narrow belt of yellow pine runs north 
and south along this eastern slope. This small group of three incre- 
ment-cores came, therefore, from a point 8 miles west of the rapids in 
the river which gave the name, several hundred feet above the river 
on its very steep south side. The dating between these three trees 
was very satisfactory. The rings were measured by Mr. Austin, and 
the standardized curve from 1765 to 1924 was smoothed in the usual 
way and is shown in figure 6. This curve has a trace of similarity 
to those at Baker and Boise, especially in respect to the apparent long 
period and its phases, but its real conformity is with the California 
curves to the south. This group shows a profound depression from 
1890 to 1894, which suggests fire or injury of some sort. The cycles 
are 7.2 (2), 12.6, 14.2 (3, oc. -*-), 16.4 (2), 18.3, 22.5, and 35. 

OREGON COAST GROUP (OC) 

This is the group of Douglas fir described in Volume I, which 
came from the low coast hills 25 miles northwest of Portland, where 
the rainfall is large and the snows of winter very rare. No real like- 
ness in rings or in smoothed curve (graphic Hann) has been found here 
to the groups farther inland. The smoothed curve is shown in figure 6. 



86 CLIMATIC CYCLES AND TREE-GROWTH 

The cycles are 6.8, 10.2 (2), 14.0 (3), 20.3 (oc. £ or £), 22.6 (2, oc. $), 
and 28.3 (oc. •£). This is of mixed type and does not readily match 
any one of the three zones. Its 14- and 20-year cycles remind one of 
Arizona, but the 10-year cycle is strongly Rocky Mountain and the 
one close to 23 years is most common on the Coast. There is prob- 
ably some relation between this set of cycles and its position close 
to the coast. 

KLAMATH FALLS GROUP (KF) 

This group of 12 increment-cores was received May 12, 1924, 
through the kindness of Mr. H. B. Rankin, supervisor of the Crater 
National Forest, near Klamath Falls, Oregon. They had been secured 
in that forest at an elevation of 5,100 feet above the sea. They cross- 
identified perfectly, and a few of them show likeness to some of the 
trees in the Boise and Baker groups. Mr. Austin measured all the 
specimens, using the long-plot method, and after standardizing, the 
curve was smoothed by graphic Hann and is given in figure 6. It 
presents no marked similarity to any other, though the Boise and 
Baker groups have real touches of likeness. Yet all the while its inter- 
nal cross-identification was perfect and its smoothed-curve variations 
look entirely normal. Its cycles are 8.5, 9.6, 14.0, 15.5 (oc. - 1 ), 19.5 
(oc. •£-), 24.2 (2, oc. •£), and 31.2 (2). This is a mixed set, but perhaps 
has a little more resemblance to the Arizona area than to the others. 

A very fine 500-year pine record was sent me on July 23, 1925. The 
tree had been cut by the Pelican Bay Lumber Company in the same 
forest on the southwest quarter of section 35, township 29 south, 
range 6 1 east, W. M., at 5,100 feet elevation and about 5 per cent 
east slope. This tree does not readily cross-identify with the 12 cores, 
and as it comes from a different place and is very old, it is reserved for 
future discussion. 

PLUMAS COUNTY GROUP (CP») 

This group of 10 increment-cores from Meadow Valley was sent 
me by Professor Emanuel Fritz, of the agricultural experiment station, 
Berkeley, California. He says: 

" Meadow Valley is eight miles west of Quincy, and the borings 
were collected in Township 24 North, Range 8 East. The region is 
very mountainous, but Meadow Valley is an ancient lake bed. The 
borings came from the southern border of the valley on a slope, less 
than 100 feet above the valley floor, elevation 4,000 feet. The water- 
supply is excellent and the soil is very rich in humus and carries con- 
siderable moisture. The forest growth is comparatively luxuriant. 
All the borings were taken in August, 1922." 

They cross-identified well and were measured by Mr. Cherry, 
using the auto-plot method. They were standardized and smoothed 

♦"California pines," the first group of that species secured from California. 



TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 87 

by graphic Hann. The curve extends from 1551 to 1921 and the part 
since 1750 is shown in figure 6. It has a distinct similarity to the 
typical Sierra Nevada curve farther south. Its cycles are 6.7, 11.8, 
13.7 (oc. -J), and 28.6 (3), which conforms to the usual ones of the 
Coast zone. 

Professor Fritz also sent a partial section of pine tree from a point 
at about 5,400 feet altitude in Lassen County, near Susanville. This 
single tree-record begins at 1588 and ends in 1922. An analysis 
obtained in the usual way gives as cycles, 16.4 (2, oc. -£), 20.2 (oc. -J-), 
24.2 (oc. i), and 29.5. 

CALAVERAS GROUP OF PINES (CVP) 

The collection of this group of increment-cores at the edges of the 
Calaveras Grove of big trees on July 4, 1924, has been described in a 
previous chapter, page 53. The additional cores, taken near Murpheys, 
showed a larger growth average of 1.71 mm. as compared to 1.25 of the 
trees near the grove, but otherwise appeared to give much the same 
record, and all were included in one group of 14. 

Mr. Hawkins measured these, using the long-plot method. An 
attempt was made in this group to standardize the individual records 
by using different gear ratios on the plotting instrument, but it was 
not felt to be entirely satisfactory, on account of the different average 
size of different parts of a single record; for instance, the larger central 
growth in early years of the tree can not be properly allowed for, and 
yet it is usually too good to discard. The average was undoubtedly 
improved by this change of gears, and there were so many trees in the 
group that it did not seem necessary to do any further standardizing. 
The mean of the 14 trees, 1621 to 1923, smoothed by a graphic Hann, 
is shown in large part (1750 to 1923) in figure 6. It is at once evident 
that this belongs to the inner collection of homogeneous Sierra Nevada 
curves. The cycles in this curve are 6.8 (2), 7.6 (2), 10.4, 14.6 (oc. £), 
21.2 (2), and 30.2, which are of the Arizona type. 

BIG CREEK GROUP (BC) 

After the sequoia trip of 1919, it was realized that no pine records 
had been secured in California to aid in the cross-dating between 
Arizona and California. Accordingly, in 1920, at the request of Mr. 
Paul Redington, district forester at San Francisco, the ranger on Big 
Creek very kindly sent me five excellent v-cuts from pine stumps at 
an elevation of about 5,500 feet on Big Creek, a northern tributary of 
King's River. This river is just north of the General Grant National 
Park and the large areas from which the greater part of the sequoia 
records had come. 

These pine specimens cross-identified among themselves exceed- 
ingly well, and there was no trouble in recognizing a number of Flag- 
7 



88 CLIMATIC CYCLES AND TREE-GROWTH 

staff dates in their rings. The average growth was nearly 50 per cent 
larger than the Flagstaff growth and many rings were immense. 
The specimens were measured by Mr. Cherry, using the auto-plot 
method. They were individually standardized by him and the result- 
ing curve from 1719 to 1919, smoothed by geometric Hann, is shown in 
part in figure 6. It agrees exceedingly well with the Sierra Nevada 
collection, which extends from Calaveras Grove to Mount Wilson. 
The cycles are 8.4, 11.2 (oc. %), 13.5, 17.4, 21.7 (3), and 35 (oc. J), 
which classify as of Coast type. 

SPRINGVILLE GROUP OF PINES (EP») 
The visit to Springville in early August 1925, and the collection 
of sequoia records, has already been described on page 54. The 10 
pine borings came from elevations between 5,000 and 6,000 feet, that 
is, from Camp Lookout to the lower edge of the sequoias, about 4 
miles away. Most of the pines had a local south exposure toward a 
canyon sloping toward the west. Some of these trees were on isolated 
points, where they could get no possible water except the rain or snow 
which fell immediately about them. Two could not be used; one was a 
magnificent 5-foot tree whose growth was too small to allow dating 
in the core and whose age therefore is probably very great; the other 
had an extensive fire injury and the rings were too erratic. Mr. Austin 
measured this group, using the long-plot method. The trees were 
standardized individually and the curve, 1720 to 1924, smoothed by 
graphic Hann, is shown (since 1750) in figure 6. It shows excellent 
variations agreeing most satisfactorily with the other Sierra Nevada 
curves between Calaveras and Mount Wilson. It is interesting to 
recall that the sequoias from Calaveras to Springville which show uni- 
form cross-identification, to a considerable extent cross-identify with 
the pines nearby. The cycles classify in the Coast type as follows: 
8.7, 11.4, 13.4 (2), 17.4 (oc. £), 23.1, 27.6 (2, oc. £), and 34 (oc. £). 

MOUNT WILSON GROUP (W) 
This group of 22 increment-borings, of which 8 are used, was made 
July 25, 1925, by courtesy of the Toll Roads Company and the Mount 
Wilson Solar Observatory, who gave permission to bore the trees. 
The top of the mountain, about 6,000 feet elevation, is a rough semi- 
circle of ridge, convex toward the west and south, with the inner area 
in the form of an amphitheater of gentle slope toward the central 
drainage wash, which flows down past Strain's Camp. Sixteen trees 
were tested in this area, of which 8 are used, all yellow pines except 
one sugar pine and one Douglas fir, each of which gives apparently 
the same record as the yellow pines. The 6 Douglas firs tested on the 
road down the mountain were defective, perhaps in part injured by 
the road building. 

♦Elster's pines. 



TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 89 

The trees which could be used were in the triangle between the 
hotel, the Observatory museum, and Strain's Camp. One of the very 
best, No. 14, is a large tree in the fork of the gulch just above Strain's 
Camp, close to the upper hall. The ring record of this tree shows 
strong Flagstaff characteristics. This group was measured by Mr. 
Erickson, using the long-plot method. The records were standardized 
and a curve, 1725 to 1924, smoothed by graphic Hann, is mostly 
shown in figure 6. This curve has strong variations agreeing excel- 
lently with the Sierra Nevada curves. The cycles are 7.7, 10.4 (2), 
11.2 (oc. i), 15.2 (oc. $), 17.1, 22.5 (2, oc. £ or £), 29.4, and 34 (2, oc. 
•J- or J-). These conform to the Coast type. 

SAN BERNARDINO GROUP (SB) 

The Forest Service in Los Angeles was kind enough to send me in 
1922 some 13 increment-cores from the San Bernardino Mountains. 
Mr. Patterson measured the rings, using the auto-plot method. Five 
were omitted because they were too short; 2 were reserved because 
they did not agree well with the others, which formed a real group, and 
because there was a slight doubt of the dating before 1850; of these 
one shows an unusually regular 17-year cycle. The remaining 6 were 
combined into the present group. They were standardized and the 
curve, 1819 to 1921, smoothed by graphic Hann, is shown in figure 6. 
The very remarkable 23-year period is the most obvious thing in it. 
In fact, a search for older trees in that region might give some very 
interesting and valuable material. This periodic feature stands out 
because certain maxima which show well in the Sierra Nevadas to 
the north are here largely suppressed. The maxima which make this 
curve interesting are all present in the Sierra Nevada curves. The 
cycles here are 7.7, 9.8 (2), and 22.9 (4), the only case of assigning a 
weight of 4 to any cycle. These belong to the Coast zone. 

CHARLESTON MOUNTAIN GROUP (CH) 

The collection of this group of seven cores and one 500-year v-cut 
on July 18, 1924, has already been described on page 61. Saw Mill 
Canyon starts just north of the main peak and cuts to the east. The 
site of these trees is about 7,500 feet elevation and has something like 
24 inches of rain. The canyon is narrow and composed largely of 
gravel terraces. Three trees high up on the very steep terrace bank 
to the south showed such slow growth that much of their records could 
not be dated, but the other specimens from the flat canyon bottom 
gave a fine agreement. The wash was dry. The 500-year stump was 
close to its north edge. The rings readily cross-identify both with 
Flagstaff trees and also with Sierra Nevada trees, thus corresponding 
to the intermediate geographical location. Mr. Hawkins measured 
them by the long-plot method, effecting partial standardizing by dif- 



90 CLIMATIC CYCLES AND TREE-GROWTH 

ferent gears in the measuring instrument. However, each tree-record 
was subsequently standardized in the usual way and the resulting 
curve, 1402 to 1923, was smoothed by graphic Hann. The part since 
1750 is shown in figure 6. This curve is strongly of the Flagstaff type 
in the last century or so, except that 1818 to 1821 have large growth 
instead of small. The cycles are 7.3, 11.4, 14.4 (oc. £), 17.8 (3), 21.3, 
25.9, 29.0, and 34. This is a Coast type. 

PINE VALLEY GROUP (PV) 

The Pine Valley here referred to is in the mountains some 50 miles 
east of San Diego, California, at an elevation of over 5,000 feet. 
The trees are more numerous at the southern end of the 2-mile valley, 
and of five increment-cores, three come from the vicinity of the 
summer resort there; one which could not be dated comes from the 
northern end and one comes from a very large tree about midway. 
Four were secured in the summer of 1923 and the undated one in 
August 1925. The rings cross-identify readily with those at Flagstaff. 
Mr. Hawkins measured the rings, using the auto-plot method. Stand- 
ardizing was effected by reducing mathematically each tree-record to a 
set of departures from its own mean. The resulting curve, 1736 to 
1923, smoothed as usual, is given in part in figure 6. This curve 
matches the Charleston group with great exactness and therefore is 
closely like the Flagstaff-type curve. The cycles are 6.6, 10.1, 14.4, 
18.4, 25.2 (oc. ^ or -J-), 32 (2, oc. £), and 35, which rather resemble 
the Arizona cycles. 

MISCELLANEOUS GROUPS 

The groups mentioned below have been collected for various pur- 
poses, but for one reason or another do not lend themselves to the 
study of cycle distribution. They are added here because reference 
has been or will be made to them. 

SEQUOIAS 

Calaveras group (CVS) — This group consists of two increments- 
cores, three v-cuts on fallen trees collected in 1924, and a tracing 
(recently measured and plotted by Mr. Austin) made by Mr. Manson 
in the 1880 's. This was copied from an original tracing, which, with 
a separate copy, was filed in the library of the University of Cali- 
fornia. A copy was loaned to me by the Department of Agriculture 
of the University of California, and another was sent me by Professor 
C. F. Marvin, chief of the United States Weather Bureau. This 
"longitudinal" record is probably from the Dance Hall tree; it goes 
back to 621 a. d. The specimen which I collected from the "Old 
Maid" goes back to 525 a. d. My record from the "Father of the 
Forest" begins at 922 a. d. 



TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 91 

Grant Park sequoias (GPS) --This group includes the 21 v-cuts 
made in 1915 and 1918 in the vicinity of the General Grant National 
Park. They are described in Volume I. 

Topography sequoias (TS) — These are 12 small and usually 
incomplete radials collected in 1919 from the Grant Park region, 
giving the last 500 years of sequoia growth and selected with respect 
to topographic contours, ground-water, and so forth, to get the effect 
of these features on the size of rings. 

Springville sequoias (SS) — These include two numbers, 22 and 23, 
collected in 1918, and 14 radials secured in 1925 from medium and 
very old trees at the old Enterprise mill-site some 20 miles east of 
Springville, California. These will be used especially in the formation 
of early tree-records and the attempt to date the prehistoric ruins of 
the Southwest. 

COAST REDWOODS 

Santa Cruz group (Z) — These are eight radial pieces of coast red- 
wood collected February 20, 1921, some 15 miles north of Santa Cruz, 
California. These could not be cross-identified and so are not dated. 

Scotia group (B) — These are 12 fine radials collected in early July 
1925, at Percy J. Brown's lumber-mill, a few miles south of Scotia, 
California. These, too, did not cross-identify and have never been 
dated. 

ARIZONA GROUPS 

Flagstaff century group (FLC) — This includes 10 pines 500 years 
old, of which one extends back 640 years, all in the vicinity of Flag- 
staff. These will form the approach to the study of early pine records 
in the Southwest, which will include many semihistoric beam sections 
from the Hopi villages, and it is hoped from the prehistoric ruins also. 

Flagstaff lava-beds (FLB) — These lava-beds are 16 miles northeast 
of town. Only two trees belong in this group, FL 48, inside the ring 
of lava, from which a 1-inch core was taken in 1920, and FL 51, just 
outside the lava ring, a v-cut from the stump. The former goes back 
to 1556 and the latter to 1598. 

Prescott group (PR) — Nos. 1 to 70 were small incomplete v-cuts 
sent me by the Forest Service in 1911, described in Volume I. Nos. 
71 to 75 are increment-borings made in 1924 to bring the Prescott 
rain comparison up to date. The records were not intended to go back 
before 1850, but some of them do. 

OTHER WESTERN GROUPS 

Pecos, New Mexico (L) — These are four radials from the forest 
near Pecos, New Mexico, sent by the Forest Service in 1920. They 
were needed for comparison with the prehistoric beams sent by Dr. A. 



92 



CLIMATIC CYCLES AND TREE-GROWTH 



V. Kidder, who has been conducting excavations in the ancient ruins 
there. The rings in these specimens are rather erratic and only one 
gave a reliable record back to about 1720. 

Raton, New Mexico (R) — This is a collection of three increment- 
borings secured near the highway over Raton Pass. Only one proved 
datable. 

Nebraska (NEB) — This is a group of 12 sections from young 
trees sent by Mr. Jay Higgins, forest supervisor, at the request of Dr. 
F. E. Clements, from the plantations on the Nebraska Forest and from 
the native yellow-pine stands near the Niobrara Division of the forest. 
The three yellow-pine specimens all cross-identify nicely and give a 
record extending back to the middle 1880 's. The jack pines, except 
one, are also reliable in dating and extend back to about 1907. The 
three Scotch pines extend back to about 1913, but do not cross-identify 
in a way to give confidence. 

In the study of western cycles a group from Nebraska would be 
very valuable, but it should go back 100 years at the least for proper 
comparison with the other western groups. The above specimens, 
however, will be most useful in climatic comparisons. 

Wind River, Washington (WR) — This group was collected June 
20, 1925, at the Wind River Forest Experiment Station, Washington, 
a most favorable location on a tributary of the Columbia River, per- 
haps 75 miles from Portland. Five increment-borings were obtained, 
one yellow pine and the rest Douglas fir. Most of these were erratic in 
growth, perhaps from injuries, and one, at least, was too much crushed 
in boring. So the group was not used in the special study of western 

cvcles. 

NORTH AMERICAN GROUPS 

American Arctic (AA) — These 21 sections, chiefly white pine and 
fir, came from high latitudes in the MacKenzie River area of northern 
Canada, by courtesy of Hon. Chas. Camsell and Mr. G. S. Hume, 
Department of Mines, Ottawa, at the request of Mr. V. Stefansson, 
the explorer. They were mostly cut in 1923. The interesting and 
gratifying fact is that they can be cross-identified for the most part 
and dated. The growth is usually very small and sometimes erratic. 
The 21 specimens are divided into three subgroups, as follows: 



Subgroup 


Average 
age 


Average 
ring-size 


Average 
diameter 


A. Nos. 1 to 6, lat. 60° N., South River group 


years 

57 

85 
100 


inch 

0.034 

.015 

.020 


inches 
4.08 
2.29 
3.94 


B. Nos. 7 to 15, lat. 65.5° N., Lake group (Great Bear Lake) 

C. Nos. 16 to 21, lat. 66.5° N., North River group 

Total, Nos. 1 to 21 


80 


.022 


3.3 





TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 93 

These have been dated, but not yet measured. Considerable 
parts of all except one can be used, but there is a tendency to show 
very small compressed growth in the early years. No. 8, the excep- 
tion, goes back to the neighborhood of 1700, but is too uncertain to 
use. No. 19 extends to about 1743, but can only be used after 1890. 
No. 10, beginning about 1792, can probably be measured. A fair 
record from 1800 will come from the Great Bear Lake region. The 
South River group extends to about 1835 and the North River group 
to 1860, with a single one to 1808. This valuable collection will be 
of the greatest help when the cycles over larger areas are studied. 

East Wareham, Massachusetts (EW) — This group consists of 
some 21 v-cuts and increment-cores secured largely in 1921, from the 
region between Wareham and Sagamore Beach. The cross-identifica- 
tion is good in most of them, but injuries have affected a number and 
many are too short and only 8 are held as worth measuring. These 
will carry a good record to 1840 and a single one to about 1795. This 
last is from the "lone pine" which used to stand in the lane about 
half a mile southeast of the Onset Junction railroad station. 

Mount Washington group — Two sections of very old black spruce 
trees from near timberline on Mount Washington have been kindly 
sent by Professor W. C. O'Kane, of the University of New Hampshire. 
These grew at about 4,000 feet elevation, were badly deformed, and 
were some 3 or 4 inches in diameter and about 275 years old. This is 
the nucleus of a valuable group. 

Mount Desert, Maine — Three increment-cores were sent me in 1921. 

NW. Pennsylvania group (PA) — This group of 10 v-cuts and 1 
increment-core, 10 white pines and 1 beech, was collected May 20, 
1922, from the logging camps of the Wheeler Lumber Company, by 
kindness of the manager, Mr. N. P. Wheeler, jr., in the higher parts 
of the mountains halfway between Pittsburgh, Pennsylvania, and 
Buffalo, New York. These cross-identify well and give a record 
extending back to about 1650. The beech shows favorable ring 
variation and gives promise of being a useful tree in such studies as 
t nPSP 

FOREIGN GROUPS 

Brazil (BZ) — Two 6-foot sections of the South American pine 
from southern Brazil were measured by the auto-plot method in the 
Commercial Museum in Philadelphia. They had been cut about 1902 
and were each close to 500 years old. They did not cross-identify, 
though the rings seemed clear and practically without error. 

Tasmania (TS) — A section of King William's pine (Athrataxis 
selaginoides Don) from 3,000 feet elevation in the highlands of Tas- 
mania, has been sent me by Mr. G. Weindorfer. It gives great promise 
of valuable cycle studies in the southern hemisphere. 



VIII. ENVIRONMENT 

This chapter deals with the effects of climate, topography, and 
other external agencies on ring-growth in trees; after which the point 
of view is reversed and the observed effects are listed as indicators of 
past climates. 

EFFECTS IN TREES 
CLIMATE 

The common factor over large areas is climate. A heavy winter 
snowfall in Northern Arizona, which supplies abundant moisture for 
the trees there, extends over hundreds of miles and supplies abundant 
moisture in northwestern New Mexico, 225 miles away, or over on the 
coast mountains, a matter of 400 miles in the opposite direction. A 
dry winter in Flagstaff is usually dry in the other places also. Even 
at much greater distances the resemblances are enough to enable us 
to carry dates across in the trees. 

Rings a climatic phenomenon — This is not surprising, for the ring 
is a climatic phenomenon. It begins with large, white rapid growth 
in the late spring when the sap flows. The usual time of this at Flag- 
staff (elevation 7,000 feet) is in late May or June and is well observed 
by the dendrograph, which magnifies the diameter of the trunk and 
shows its daily and hourly variations. In this arid climate, spring 
growth depends on the precipitation of the preceding winter, for the 
months of April, May, and June are exceedingly dry. In July and 
August come the heavy summer rains with a large run-off and little 
benefit to the trees. When the season closes, there is a gradual cessa- 
tion of the activity of the tree, owing to lowered temperature and 
diminished water-supply. This causes the deposition of harder 
material in the cell-walls, producing in the pine the dark, hard autumn 
part of the ring and the protecting bark. The growth stops altogether 
in winter. 

Small single rings — If the winter and spring have been unusually 
dry, the Arizona tree may stop growing by summer. The resulting 
ring will consist of a small white spring growth and a threadlike red 
outside growth. In old trees the ring may become microscopic or 
appear as a thickening of the red ring of the preceding autumn, and 
even disappear altogether in parts of the circuit of the trunk. In 
some extreme cases, sections could be found in which a ring or two 
is absent from the entire circuit. Very likely it was active for a time 
but not long enough to leave white cells. 

Double rings — On the other hand, if the winter precipitation has 
been normal, the tree passes through the spring drought and reacts 

94 



ENVIRONMENT 95 

to the summer rains and displays additional growth. As a rule, near 
Flagstaff this late growth is very much less in width than the spring 
growth, usually between 10 and 20 per cent, rarely going to 30 per 
cent. When it is more than 15 per cent, it begins often to show a 
double effect, with its central part lighter than the red on each side. 
In extreme cases this autumn growth actually gets back to the color of 
spring wood and the growth becomes nearly white, thus separating 
off an extra red ring that is rarely hard to distinguish from the annual 
autumn red ring. The distinctive feature is that the false ring fades 
gradually on both sides, while the true autumn ring fades gradually 
on the inside but ends abruptly on the outside. 

Doubling and locality — The trees near Prescott show an extra- 
ordinary number of extra rings, usually easily distinguished by the 
criterion just mentioned. Some trees there have extra rings unusually 
small and sharp and separated by very white tissue. Such rings are 
more difficult to recognize. Sometimes there was more than one 
false ring. In such cases it is evident that the storm is very important 
to the tree. At that elevation, 5,200 feet, the rainfall is much less 
than at Flagstaff, and each rainy season is more nearly a series of 
isolated storms. 

The soil on which these Prescott rings grew is a disintegrated 
granite which forms a very efficient reservoir, holding abundant 
water with little leakage. The top of Mount Wilson is very similar 
in type of soil, though not in climate, for it has a single rainy season in 
winter. Double rings are practically unknown there. At the lower 
levels of the Santa Rita Mountains near Tucson the soil and also the 
climatic conditions are again similar to those at Prescott. The trees 
there depend on summer rains even more than at the northern moun- 
tains and the doubling character is more conspicuous and bothersome. 
Thus it is seen that doubling is a local climatic effect. 

Doubling and age — Doubling is far more conspicuous in the earlier 
or "youth" rings of a tree when the trunk is rapidly increasing in 
size. These youth-rings are larger and less sensitive than the later 
rings. Of course, it is more apparent in large rings, and any tree which 
grows rapidly is more likely to show it. However, without specially 
investigating the point, one is inclined to think that young trees, 
being less sensitive than mature ones, are a little more certain to 
continue their growth into autumn and so do have more doubling 
than mature trees. This could be tested by the dendrograph on 
properly selected trees. 

Doubling and summer rains — Since in double rings the space 
between the false ring and the outside of the real autumn growth is due 
to summer rains, it seemed possible that this segregated autumn 
growth might give a measure of the summer rains. This was called 



96 CLIMATIC CYCLES AND TREE-GROWTH 

at the time " partial ring study." As far as the matter was carried, 
the autumn growth was found to be much more closely proportional 
to the spring growth and to the winter rains than to the summer 
rains. The matter is one of some complexity, because records of the 
rains themselves are extremely incomplete, owing to their local and 
torrential character and heavy run-off. As a result, the tree-records 
of such rains are local and seem of much less value at the present 
stage of their interpretation. 

Doubles and cycles — In the early Flagstaff work there were two 
500-year trees which showed a remarkable half sunspot cycle for 
nearly 200 years, beginning soon after 1400. One of these was espe- 
cially perfect in this cycle, showing it with most remarkable regularity 
(see fig. 17 and Volume I, fig. 32). This tree also was full of double 
rings. It has suggested the general question as to the character of the 
record of trees which show many double rings. Is such a record 
different from those in other trees? So far the answer is thought to be 
negative, but there is further work to be done on this point. 

Doubles and high altitude — As one studies the upper levels of the 
yellow pine, above 7,000 feet elevation near Flagstaff, the double or 
extra ring becomes less and less common. So far as tests go, it does 
not appear at all in the highest trees. In these higher trees the rings 
are more complacent, there is apt to be less pitch, and so less red color, 
in the autumn part; yet this autumn part shows a large proportionate 
size. Here probably the summer rains play less part in the tree's life, 
for they are too local and the run-off is too big. But the winter snows 
especially are too heavy, the ground stays moister, and falling tem- 
perature is more often the agent which stops the yearly growth. 

Other trees — As stated above, the yellow pine in California shows 
very rare doubling. Douglas firs and sequoias practically never have 
it, but piny on and juniper at the lower levels in Arizona are badly 
subject to it. 

Large single rings — If rains in Arizona are abundant and well 
distributed, growth extends beyond the summer period. A good 
distribution here does not mean that they assume at all an even dis- 
tribution, for in many years evident division into wet and dry 
seasons has never failed. In a long drought the summer and winter 
rains decrease and the spring and autumn rains disappear, sometimes 
entirely. In wet periods, summer and winter rains are heavy, and 
spring and autumn rains come every few weeks. In this latter event 
the trees carry their growing-season into autumn. Thus, without 
putting on any preliminary red ring, they show a wide growth of 
white tissue, ended in autumn by a dense, narrow red ring. 

Rings in buried trees — In the vicinity of Flagstaff a considerable 
number of buried trees have been washed out at depths from 18 



ENVIRONMENT 97 

inches to 16 or 20 feet. The upper trees have rings of modern type, 
while the lower ones show enormous rings up to a centimeter in size. 
They exhibit two characteristics which go with larger water-supply 
than noted to-day in Arizona. The centers of the white parts of the 
youth-rings show sometimes a softening that gives an effect almost of 
an abnormal ring. And when the tree is old the red part of the rings 
is very massive and wide in proportion to the rest, and the ring 
sequence is subject to characteristic " surges" which are common in 
European and other wet-climate trees. In this surging there is con- 
siderable difference between largest and smallest rings, but the change 
from large to small or the reverse is gradual, so that the mean sensi- 
tivity is low, though the rings show strong variations. This sort of 
thing is very different from the habit of the living Arizona trees. 

Certain small white needle-shaped crystals discovered in these 
ancient stumps were identified by Dr. F. N. Guild (1920, 1921) as the 
first observed occurrence of terpin hydrate as a natural mineral. 
On account of the location, it was named " Flagstaffite." 

RAINFALL CORRELATIONS 

If successive years were exactly alike, the rings would all be of the 
same size, with some alteration with age or injury. But successive 
years are not alike, and in their differences there are climatic factors 
which appeal strongly to the tree. In northern Arizona, with its 
limited moisture and great freedom from pests and with no dense 
vegetable population, and with the seasonal correlations above de- 
scribed, this controlling factor is unquestionably rainfall. This is 
entirely in accord with the rainfall comparisons given below. 

Prescott growth and rainfall — This was worked out to 1908 in 
Volume I. Its insertion here is to call attention to figure 7, which 
gives tree-growth and rainfall at Prescott extended to 1923, with a 
new calculation of rainfall from growth, using the method described 
in the previous volume. The discrepancies in the last few years 
probably arises from the error of boring trees too near the roads, as 
was the case with the recent collection. The calculations and plotting 
for these curves were done by Mr. D. A. Hawkins. 

Flagstaff tree-records and rainfall — The official Weather Bureau 
records at Flagstaff began in September 1898. Hence, there are very 
few years for comparison with tree-growth. A gain has been made by 
using fragmentary records beginning in 1888 and filling in the deficient 
months by estimation, using for comparison various records in other 
localities of northern Arizona, such as Holbrook, Fort Defiance, 
Prescott, and so forth. Practically all the precipitation after November 
1 falls as snow, and hence that date is used as the beginning of the 
year in reckoning rainfall. But even so the total rain does not show a 



98 



CLIMATIC CYCLES AND TREE-GROWTH 



correlation with tree-growth. So, remembering that the torrential 
summer rains do not greatly benefit the trees, the year was divided, 
as it is naturally, into winter and summer precipitation, the former 
from November 1 to June 30 and the latter from July 1 to October 31. 
It was immediately evident that this removed the unexpected dis- 
agreement, for the winter values closely resemble the tree-growth, while 
the summer rains (averaging 10 out of an annual total of 23 inches) 
show no relation to the growth. This is shown in figure 8. Though 
the length of record is not great enough to test satisfactorily any for- 
mula for reducing rainfall to tree-growth, or the reverse, the evidence 
indicates that the same principle of accumulated moisture used in the 



2J0O\ 



S '-co 

S 



o 

30 

■ 

o 
a 
i-t 

10 




F rescott tree gr owth 



2and3 




— 

30- 



20- 



Prescott r linfall calculate J from tree gro vth 



r 




Presc stt rainfall Nov 



to Nov. I 



0' 

I860 



1670 1880 1890 1900 1910 

Fig. 7 — Prescott rainfall and tree-growth 



Prescott correlation (Volume I, p. 66) applies here. The accumulated 
moisture curve for the winter precipitation at Flagstaff is shown in 
curve 4 of the figure. 

Flagstaff and Prescott difference — In the correlation between 
rainfall and tree-growth at Prescott, it was not necessary to segregate 
the winter rains for the purpose, because the correlation was apparent 
when using the annual total. But in the Flagstaff area the winter 
precipitation only can be used. Without doubt this difference arises 
from the topography of the country. Prescott is situated in the lap of 
the Bradshaw Mountains opening to the north and protected from the 
southerly summer winds, while the Flagstaff area is mostly on the 
south side of the lofty San Francisco Mountains, about which summer 



ENVIEONMENT 



99 



clouds gather more easily perhaps than at any other point in Arizona. 
The summer rains, especially near these mountains, are intense and 
local and are likely to destroy any correlation. 

Arizona-California rain record — There is a further important 
advantage in using only the winter rainfall, namely, that such pre- 
cipitation is essentially alike in Arizona and California. Since the 
coastal region has practically no summer rain to complicate the situ- 
ation, the trees of Arizona become admirable recorders of California 
rainfall. In fact, it seems probable that these Arizona trees give a 
better record of California rainfall than do the California trees, so far 



Flagstaff 

Nov.!' 



n*Ufl:Summer [^ Va/X W^V^ A W 



Flagstaf) 
preci 




1850 1860 1870 1880 1890 1900 1910 1920 

Fig. 8 — Flagstaff rainfall and tree-growth, with comparison curves; the tree-growth shows 
close relation to winter precipitation 

discovered, though it is possible that very carefully selected sequoias 
will be found to give good records. This similarity in rainfall appears 
in figure 8, where the Flagstaff, Prescott, San Diego, San Francisco, 
and Mount Wilson rainfall curves are reproduced. From a meteoro- 
logical point of view the similarity is not surprising, for the winter 
storms of northern Arizona cover very large areas and come from the 
coast with very trifling modification, giving precipitation in Arizona 
about one day later than in California. 

Cibecue drought record — Figure 9 shows the record of a single 
tree, J-3, as measured by the auto-plot method. It shows the droughts 
between 1870 and 1905 in a striking manner. 



100 



CLIMATIC CYCLES AND TREE-GROWTH 



Sequoia growth and rainfall — The attempts in the previous volume 
to find a real correlation between sequoia growth and precipitation 
(p. 70) were not satisfactory. Figure 10 shows a decided improvement 
brought about by the high-level trees, D 1-5, corrected for gross rings 
and compared with rainfall at San Francisco. There seems to be a real 




1850 I860 1870 1880 1890 1900 1910 

Fio. 9 — Cibecue drought record traced directly from autoplot 



1920 



relationship here, even though it does not yet equal the Prescott 
correlation. 

Comparison records — There is yet much to be done in this com- 
parison between tree-growth and rainfall, but the obstacle everywhere 
is the lack of rainfall records near the trees and over adequate periods 
of time. The five Prescott groups showed that in a mountainous 
country nearness is very important. Until very recently the nearest 
records to the sequoias were 65 miles away and at an elevation 500 



San Francisco rainfall 




Mlj 
3.0 jf 

zx>.S 



i-o, 



1850 I860 1870 I860 1890 1900 

Fio. 10 — Sequoia growth and rainfall 

feet lower. Colonel John R. White, superintendent of the Sequoia 

National Park, is greatly to be commended for starting adequate 

records there. 

CONSERVATION 

In the Prescott correlation, as discussed in Volume I, a conser- 
vation formula was applied, based on the idea that the accumula- 
tion of excesses or deficiencies in moisture affect the general activity 
of the tree. One might say that the trees respond each year to 
the amount of rainfall, but that their vitality is affected by the 



ENVIRONMENT 101 

conditions for some years back. Thus, during the dry period from 
1870 to 1905 or so, the trees responded each year to the fluctuations 
in rainfall, but with less and less spirit. This suggested that the con- 
servation was in the tree itself. 

Reversed conservation — In considering the details of smoothing 
curves of tree-growth (page 44), it seemed as if the derived value should 
substitute for the last of the several used in getting it, but as a matter 
of fact there appeared to be better agreement with rainfall when the 
derived value was placed in the middle, as in the graphic Hann, used 
so much in the western groups. This could only be true if favorable 
years affect the preceding year as well as the one after. And in the 
growth of trees that is not impossible, so far as we know at present, 
as will appear in the next topic. 

Possible change in ring-size — The sapwood commonly holds much 
reserve moisture which can without doubt be drawn on for the needs 
of the tree and whose depletion can be changed to abundance when 
conditions are favorable. It may be that the conservation or vitality 
of the tree lies in this storage capacity. If so, it is entirely conceivable 
that the moisture condition of the growing layer affects the actual 
size of the rings near it, and that the ring-size is not absolutely fixed 
for several years after its growth. A first attempt to test this matter 
by borings in the same tree (FL-90) at 4-year intervals was not satis- 
factory, because the cores happened to show some slight irregularities 
in growth and were allowed to dry before measurement. Such varia- 
tions as are referred to here might show in the dendrograph.* 

Water-soaked rings — As an illustration of probable change in 
ring-size in dead trees from excessive water-content, reference is here 
made to the tests on a fallen sequoia described on page 24. 

Repeated use of rain — Somewhat connected with the subject of 
conservation is the matter of the repeated use of rain. In separating 
the rainfall at Prescott into winter and summer records, the cycles of 
the winter rains at Prescott seem to be repeated in the summer rains, 
but the important ones in the summer rains do not carry over to the 
winter. This seems to mean that winter moisture lasts over locally to 
summer, but summer moisture mostly runs off or evaporates. This 
difference comes from the different types of storms in winter and 
summer. In the former, the storms come from the coast and clouds 
are continuous over an immense area. There is no chance for evapora- 
tion of any amount. On the other hand, in summer the sun is very 
powerful and each morning promotes evaporation over large areas 
between the scattered clouds. Storms come from the south and con- 

*Since the above was written, Dr. MacDougal has told me that he has detected with the 
dendrograph certain changes in the thickness of the two or three outer annual rings, depending 
on the temporary condition of the moisture-supply. 



102 CLIMATIC CYCLES AND TREE-GROWTH 

sist of immense masses of warm air laden with moisture. When these 
pass over a large mountain, they are thrust up in the air and start the 
storm. When there is not enough motion in the air to draw in distant 
moisture, clouds form directly over the valley, evidently composed 
of moisture from the valley. As the day goes on and the air gets a 
general motion, these clouds are carried forward and contribute to the 
rainfall in adjoining localities.* 

OTHER CLIMATIC CORRELATIONS 

Several factors may enter into the tree-rings at the same time; for 
example, rainfall, temperature, length of growing-season, and direct 
solar stimulation. These may be isolated in two ways. We may 
select and study a special region, as northern Arizona, where nature 
has chosen out some one factor and made it preeminent, as rainfall. Or 
we may isolate certain relationships as in any other investigations, by 
using large numbers of observations, that is, many trees, and averag- 
ing them with respect to one or another characteristic. 

Temperature — Undoubtedly temperature and the resulting length 
of growing-season enter tree-growth. At high elevations this becomes 
the controlling factor. Probably that is the reason the Upper Flag- 
staff group, FLH, shows departures from the usual curve of that area. 
But there is no evidence that temperatures affect the lower pine 
growth to any important degree, nor the sequoia growth, especially 
in the southern groves, for sequoias at the highest and coldest levels 
promptly respond to increased water-supply by enlarged growth, as in the 
case of D-31, referred to below in connection with sequoia topography. 

Wind — Reinforced rings (see page 32) are interpreted as due to 
wind or other pressure exerted in a constant direction. In the pre- 
historic material from the ruins northeast of Flagstaff, such rings 
rather plainly indicate exceedingly strong spring gales from the west 
or southwest, if we can judge by conditions at the present day. 

TOPOGRAPHY 

The broad effects of topography were encountered and recognized 
in large measure while searching for the oldest sequoias. Almost at the 
start it was realized that size is far from a final indication of age, for 
nearness of water alters the rate of growth profoundly; for example, 
it is possible to assign 2,500 years as the approximate time it took 
the General Grant tree, which has no running water near it, to reach 
its present immense diameter of close to 30 feet. But about 3 miles 
west, near a running brook, is a stump which is over 25 feet in diam- 

*In Tucson we have perfectly clear views of the Santa Rita Mountains 40 miles south and 
7,000 feet higher than the city, the Rincons 20 miles east, the Catalinas 20 miles north, also 
close to 7,000 feet higher, the Casa Grande and other mountains 50 miles northwest, and the 
Tucsons, 15 miles west, and so on. Cloud formations are easily seen. 



ENVIRONMENT 103 

eter, but is only about 1,500 years old. That rapid growth is the 
effect of contact with an unfailing source of water. 

SEQUOIA TOPOGRAPHY 
In selecting specimens to settle a dating problem, in 1919, prefer- 
ence was given to trees at such distance from the obvious water- 
supply that the specific dependence of trees on the nearby brook 
could be tested. Thus from Redwood Basin, 15 miles east of the 
General Grant Park, a total group of 21 sequoias was obtained. The 
trees were scattered for a mile along this valley, whose slope faced 
the north. The upper or southern end is near the top of the moun- 
tain, but a spring supplies a small stream of water. The upper 
trees mostly had a very dry soil, while those below, some 600 or 
700 feet in vertical measurement, had more level ground and greatly 
increased moisture. The average growth per century in the last 500 
years was about 7.6 cm. The least was less than 4 cm. and the greatest 
was over 15 cm. The fast-growing trees were mostly close to the 
water-course in the lower basin. The average growers were mostly 
around the edges of the basin, while the slow-growing trees were 
chiefly at the tops of the slopes. Three larger growing trees close to the 
upper limit formed interesting exceptions. One was a youthful 
sequoia, only 700 years old when cut, and therefore naturally a fast- 
growing tree. Another at the very highest point was about 50 yards 
above the spring and undoubtedly tapped an underground flow of 
water leading to it. Its type of rings was very similar to those in the 
basin. The third exception had very large rings, but they were full 
of sensitive variations like the slow-growing trees nearby. This 
tree is probably over a pocket of water whose help increased its growth, 
but which failed in extremely dry conditions. It is evident, then, 
that with the sequoias moisture may control the growth up to a 
maximum fully four times as large as the minimum. 

Ring-type and moisture — The type of ring and its adaptation to 
identification and study varies greatly with the moisture-supply. 
The large rings of the quick-growing trees are either very complacent, 
that is, of the same size for many years in succession, or gross in 
character, which means extraordinarily large rings here and there; 
and their whole grouping is apparently subject to slow surges in size 
as one glances across the sequence from center to bark. Gross rings 
in one tree have about an equal chance of appearing or not appearing 
in any other tree near by. Since gross and complacent rings have little 
individuality, it is not always easy to identify their dates, especially 
if the outer layers of wood have been cut away, as was usually done 
in felling the sequoias. On the other hand, the slow-growing, low- 
moisture trees are full of irregularities which may be recognized in 
tree after tree, thus rendering accurate dating a remarkably easy 

8 



104 



CLIMATIC CYCLES AND TREE-GROWTH 



process. It is also immediately evident that these latter sensitive 
trees give short-period variations far more accurately and effectively 
than the complacent trees. These types, as well as the following one, 
are illustrated in Plate 3 and figure 3. Yellow pines in the dry climate 
of Arizona at so low an altitude that they have the utmost difficulty 
in getting water to prolong life become extraordinarily sensitive. In 
the same tree one finds some rings several millimeters across and others 
microscopic in size or even absent. 

Mean sensitivity — Mean sensitivity, which expresses this different 
quality in the trees (page 29) depends in large part on the relative 



q Growth above average 

u Average growth 

x Growth below average 




Fig. 11 — Land contours and annual growth of sequoias in Redwood Basin 

response of trees to climatic influence and so long as there are no large 
changes of ring-size due to injury, it gives a good criterion of climatic 
effects in trees. Such appears to be the meaning of figure 12, in which 
the 10 Prescott trees used in the original rain comparison are plotted 
with respect to ring-size and other features, including calculated mean 
sensitivity. The first curve shows them arranged in order of ring- 
size. The second curve, apparent mean sensitivity, estimated by 
inspection only, shows that such estimates may be too much affected by 
ring-size to be of value. Curve 3 shows that sensitivity is independent 
of ring-size. Curve 5 shows that correlation with rainfall had a slight 



Carnegie Inst, of Wash. Pub. 289, Vol. II (Douglass) 




/0<f 



A. Sequoia topography, ridges; area of D-l, 2, 3, 4, 5, IS, 19, 28, 29 and 30 




B. Sequoia topography, basins; area of D-6, 7, 8, 9, 10, 11 and 27 



ENVIRONMENT 



105 



tendency to improve in smaller rings, and assuming some error in 
tree No. 69, mean sensitivity is an excellent indicator of a tree's 
accuracy in recording rainfall. Curve 4 hints that visual comparison 
between curves of rainfall and tree-growth was not very different from 
a mathematical correlation test. 



2.5 
2.00 

1 1.5 
1.0 

05 
10 
8 

2 6 

4 
3 
2 


3 4 -o 
ao 



4! 'o 

.80 




.70 



.60 




/ 



/ 



, No; standardized^ 



M 




/>.. 



/ 



yj-T^-J-Stdndajrdiz ed \ 



trees 



Mean ring size 



>4'7 
/ 



Apparent mean 
sensitivity 



Mean 
sensitivity 



Visual comparison 
with rain 



Correlation 
with rain 



61 70 64 62 65 68 69 63 66 67 
Tree number 
Fig. 12 — Ring-size, sensitivity, and rainfall correlations, Prescott 

Sequoia contours and cycle lag — Variations in the smoothed 
curves are much greater on the ridges than in the basins, where the 
water-supply is far more abundant. The complacent basin curves 
smooth out the shorter variations. A lag in the basin trees might be 
expected, since the water takes time in getting there from the higher 



106 CLIMATIC CYCLES AND TREE-GROWTH 

surroundings. This has been sought by comparative analyses of basin 
and ridge trees. A lag of 3 years or more could have been detected, 
but none was found. There may, of course, be a shorter one. 

PIKE'S PEAK TOPOGRAPHY 

Pike's Peak contours — In collecting 47 specimens from the vicinity 
of the Cog Road on Pike's Peak in 1920, locations of test trees were 
selected with reference to contour and water-supply. The region 
lends itself exceedingly well to such tests. The valley bottoms are 
v-shaped rather than rounded, as in the sequoia basins. The sides of 
the valleys extend for great distances at a somewhat even slope. 
Water is far less abundant and the trees are left more to their own 
resources, as it were. The trees are scattered generally and one can 
get north and south exposures, stream contact, and other features. 
The soil material is relatively homogeneous compared to the Flag- 
staff region, where transition is abrupt from limestone to lava or the 
reverse, and hence tests are impeded on this account. However, on 
Pike's Peak the same tree does not cover all the conditions tested, and 
so each must be taken separately. 

Yellow pines — Four groups had yellow pines in them, as follows, 
in order from north to south : Upper North Transect, 5 ; Lower North 
Transect, 2; Brook, 2; South Transect, 2. The mean ring-sizes in 
order were, 1.26, 1.60 (variable), 1.74, and 0.81 mm. The first and 
second of these showed considerable internal variation. The trees 
on gentler slopes or in small side-gullies had the larger mean growth, 
while trees on the very steep slopes toward Ruxton Creek had very 
slow growth. The largest growth was near Jack Brook, the two yellow 
pines there being some 20 feet above the water (and near the dendro- 
graph tree). The smallest growth was on the South Transect, with 
its ridge topography, very steep slope, and sand areas indicating 
dryness. 

The south-exposed North Transect, near the foot of a long moun- 
tain slope, has growth 75 per cent greater, and the brook has growth 
100 per cent greater than the South Transect, which extends nearly 
to the top of a low, dry ridge. The extra brook growth is obviously 
a question of water-supply. So we infer that the added growth on the 
North Transect is due to moisture-supply also, and from the simi- 
larity to the Flagstaff area in some prominent features of the tree 
record, this better moisture-supply comes in the snows of winter. This 
has been considered in some detail, because the Douglas firs next con- 
sidered give similar results. 

Douglas firs — Douglas firs occur also in the same four groups: 
Upper North Transect, 3; Lower North Transect, 3; Brook, 4; and 
South Transect, 6. The respective mean growths are 1.09, 0.99, 1.20, 



ENVIRONMENT 107 

and 0.43 mm. The apparent strong effect of slope in different parts 
of the North Transect appears again here and emphasizes the value 
of further work directly on that point. The growth on the North 
Transect is 142 per cent greater and at the brook 179 per cent greater 
than on the South Transect, and the same inference prevails as with 
the yellow pines. 

Limber pine — Limber pine (Pinus flexilis) occurs in the three 
transect groups and the basin group at 9,500 feet. Three trees in the 
basin have a mean ring-size of 0.69 mm. The others of two trees each 
have 0.93, 1.02 (variable), and 1.00 mm. (variable). Thus, we can 
not make conclusions from the data on this tree, except that the 
reduced growth in the basin, 9,500 feet elevation, is very likely a 
result of temperature. 

Engelmann spruce — Two specimens of this tree in the timberline 
group, 11,500 feet, give a growth of 0.95 mm., and four specimens at 
the brook give 1.16 mm. This difference is quite as likely to be tem- 
perature as moisture. 

Fox-tail pine — Three trees of this species, Pinus aristata, were 
included in the timberline group, with an average growth of 0.63 mm. 

Age correction — No age correction has been used in these figures, 
but as the selection of trees uniformly favored the larger and older ones, 
it is not likely that such correction would materially alter the results. 

Summary — The area tested on Pike's Peak lies on the east slopes, 
chiefly below the basin. The pines and Douglas firs here show evidence 
that water is the prominent controlling factor, the pines having some- 
what larger growth than the firs. The limber pines tested had an 
average growth between the other two, but were variable and, except 
that they give the same tree records as the others, there was no decisive 
material regarding their sensitiveness to moisture-supply. A single 
group of fox-tail pine gives a similar curve. Engelmann spruce had a 
larger growth at the brook, 8,700 feet, than at timberline, 11,500 feet, 
and its ring record is far different from the other species tested. Near- 
ness to running water greatly increases growth in all the species, and 
apparently in the yellow pines and firs does not interfere with their 
success as climatic recorders. 

SAN FRANCISCO PEAKS AREA 

These beautiful peaks, 12,760 feet high, 10 miles north of Flagstaff, 
have the rounded mass of an ancient volcanic cone, with the huge 
outlying spread of Elden Mountain (9,000 feet) stretching off to the 
southeast. They are surrounded by pine forest for miles in every 
direction and give favorable opportunity for certain tests. 

Altitude effect — Two groups, all yellow pines, may be compared 
to get an idea of this effect, namely, Fort Valley, at an elevation 



108 CLIMATIC CYCLES AND TREE-GROWTH 

of 7,300 feet, at the southwest base of the mountain, and Flagstaff 
High group, at 9,000 feet, directly up that same southwestern slope. 
The first effect of altitude is an increase of mean ring-size from 1.10 
mm. to 1.95 mm. resulting without doubt from the increase of pre- 
cipitation at the higher point. The rings themselves of the higher 
group appear far more complacent, but can be dated in terms of the 
Flagstaff series. In comparing the smoothed curves of the two groups, 
the variations (those which become conspicuous in the cycle plots) 
decrease from 34 per cent at Fort Valley to 25 per cent in the upper 
location, and at the higher point lose much of their resemblance to the 
other smoothed curves of that region. On comparing the cycles one 
finds at the upper station the 17.3-year length, which is very rare in 
the Arizona area. It is more common in the Rockies and on the 
northern coast. 

Shadow — As previously explained, mountain shadow is an expres- 
sion which here refers to the side of the mountain away from the 
direction from which storms usually approach. It is, of course, on 
the east side of the San Francisco Peaks, since the winter storms come 
from the west and southwest. Two groups were taken to the east 
and northeast of the peaks; the shadow group (SH) close in at the 
foot of the steep eastern slopes at about the same level as Fort Valley, 
and Flagstaff Northeast group (NE), about 7 miles farther out from 
the mountain center and at the edge of the pines at an elevation some 
500 feet lower. The ring-sizes in the SH group is 1.52 mm. and in the 
NE group 1.17 mm. The cycle variations of the former are about the 
same as FV (34 per cent), but the corresponding variations of NE are 
near 70 per cent. On examining the smoothed curves each seems to 
be free from short interfering cycles, and perhaps this is its special 
quality. The difference between them appears to be a question of 
water-supply, which is abundant very close to the mountain, but 
rapidly decreases to the east. This same characteristic of relative free- 
dom from short-period cycles appears in the Lower Rim and the 
Cibecue groups and in the Charleston Mountain group. 

Soil and bed-rock — Many of the Flagstaff groups grew on soil that 
was not distinctive. The first, for instance, was on deep soil formed 
by an outwash fan from Woody Mountain, which is igneous rock. 
The 500-year trees of FLU grew on a considerable soil over lime- 
stone. Probably the old group at Lake Mary, whose curve is given 
in Volume I, page 26, illustrates best the effect of this limestone 
soil. Its mean ring-size is about 0.75 mm. It shows rather stronger 
variations than the FL curve. For comparison, a group of two trees 
at the Lava Beds, 15 miles northeast of town, may be quoted. These 
trees were about 350 years old and show large growth when the trees 
were small and then a very long continuance of uniform small growth 
(0.50 mm. in one and 0.75 in the other), with slight variation. Lava 



ENVIRONMENT 109 

soil of this sort is full of clay which is formed by decomposition of the 
rock. It is therefore water-tight compared to limestone soils. Hence, 
moisture caught in the former stays in place and produces a uniform 
tree-growth, while moisture entering the limestone soils readily passes 
away from the roots. The growth over limestone has larger percent- 
age variations with better climatic relationship. This confirms the 
reference to this topic in Volume I, page 22. 

Soil-moisture gradient — It is possible that a criterion of this 
difference could be found by the vertical soil-moisture gradient. 
Certain species of pine can grow in very wet land. In such cases the 
soil is wet at the surface, then soaked, and then full of water as one 
goes down a few feet. Tree sections occasionally appear which show 
an enormous increase in growth on draining such land. At an eastern 
point (Cape Cod, Massachusetts) the surface soil near the pine trees 
is sandy and below that are moist glacier gravels, down to water at 
20 feet. In contrast with this, the trees around Flagstaff grow mostly 
on a thin layer of soil, perhaps 2 to 10 feet, upon impervious, igneous 
rocks, or upon porous and cracked limestone. Over the igneous rock 
is often a layer of clay. During a large part of the year one may dig 
about the tree, or near the tree, and find the ground apparently dry. 
Clays and volcanic rocks hold layers of moisture for a considerable 
time, but the soil over the limestone, as observed in some cases, gets 
drier and drier as one goes down. The average soil-moisture gradient, 
therefore, seems promising as a help in determining certain controlling 
factors in tree-growth. 

Root conditions — Mr. G. A. Pearson, director of the Southwestern 
Experiment Station, has very kindly supplied data regarding depth 
of the root systems under certain trees near Flagstaff and per cent of 
available soil-moisture, as follows: The greatest depth attained by 
tree roots is usually around 4 feet, but only a few of them reach this 
depth; the great masses of roots are found in the upper 2 feet. In the 
case of spruce, very few roots are found below 1 foot in depth. These 
measures cover the woodland (cedar), yellow pine, Douglas fir, and 
Engelmann spruce. In his bulletin entitled "Natural Reproduction 
of Western Yellow Pine," a series of graphs shows the available soil- 
moisture in per cent of dry weight of soil, for the summer months, 
including May to September. At 6 inches in depth the amount for 
cedar and yellow pine varies from 1 to 9 per cent, and for the other 
trees about twice as much. At 12 and 24 inches of depth the amount 
for pines and cedars is between 5 and per cent, and for the other 
trees about twice as much. The precipitation curves during the same 
seasons, 1918 and 1919, show that rainfall in the preceding months is 
felt by these trees at 6 inches, and by the high-level trees, fir and spruce, 
at 12 inches of depth, for at such levels the rainfall is greater, but at 2 
feet only the Douglas fir shows it. 



110 CLIMATIC CYCLES AND TREE-GROWTH 

CHANGING CONDITIONS 

The preceding topographic conditions are constant and their 
effects are sought by comparing trees in one location with those in 
another. The results are practically constant in any one tree. But 
changing conditions produce internal alterations in each tree and 
may often be recognized in the ring record after allowing for the normal 
change of ring appearance with age. 

Shade — The Vermont hemlocks from the edge of Mount Ascutney, 
near Windsor, showed a doubling of yearly growth about 1808, due prob- 
ably to cutting of adjacent trees at that time (Volume I, pages 41, 42). 

Drainage — A small section of Scotch pine in the Berlin Museum 
shows minute rings for some 40 years and then suddenly the growth is 
quadrupled. As the history of the tree showed, this was caused by 
draining the very wet land on which it grew. 

Soil deficiency — A very interesting relationship was recognized 
by studies in Chaco Canyon in 1926. For 10 years it had been noticed 
that certain prehistoric or early historic trees showed normal growth 
to a very good size and then rather quickly the growth dwindled down 
to a great number of microscopic compressed rings from which there 
was no recovery. In human language, the tree starved to death. 
Some of these specimens came from Chaco Canyon and a number came 
in 1926 from Wupatki, a ruin 35 miles northeast of Flagstaff, in the 
region of the Lava Beds and volcanic cinders, which suggested showers 
of volcanic ashes as a means of killing forests. But on the bare rock 
mesas about Chaco a few pines were found in favorable spots where a 
little soil covered the bed-rock. Some were dying, some dead, and a 
very few in good condition, but most of them showed the compressed 
rings for the last 50 or 100 years. Evidently there was enough soil for 
small trees, but not enough to support full-grown trees, and the 
shallow beds of soil were drying out and in many cases blowing away. 
One small pine in bad condition had 2 feet of horizontal roots bare 
before any of them were covered by soil. This lack of soil and change 
in its condition, then, is the common cause of that sort of outer com- 
pressed rings in this arid area. 

Close grouping — A test for the effect of close grouping of trees was 
made on the Fort Valley group. These effects have already been 
described in connection with tree selection, page 12, and eccentricity 
of ring-growth, page 22. 

Injuries — The injuries chiefly recognized in the western groups are 
fire and lightning-scars, already referred to in the selection of trees, 
page 14. 

Pests — This topic is a recognition that such effects are of great 
importance in the general consideration of tree-rings. Where moisture 



ENVIRONMENT 111 

and sunlight are abundant and vegetation is densely crowded and 
competition is intense, as in wet-climate forests, many individuals 
must perish, and pests are largely the agent. Climatic conditions 
influence these pests and we find therefore climatic variations in the 
trees injured by them, but such effects are apt to be more hidden and 
less clear and direct than in the dry Southwest, where the trees are 
isolated and rainfall is the controlling factor. Pests, of course, attack 
the trees in different ways, but when the growth is seriously interfered 
with the rings show diminished size and may disappear, and abnormal 
growths may enter. 

ENVIRONMENT INDICATORS 

The preceding pages of this chapter have dealt with the effects in 
tree-rings of various exterior forces; the present paragraphs are 
intended as a brief introduction to the general reversal of this process, 
namely, estimation of exterior conditions by internal evidence in the 
trees. So far as rainfall is concerned this is not new, for most of the 
work done by the writer has had that purpose as its central theme. 
But in approaching the study of prehistoric and geologic material, 
the general consideration of all information contained in the rings 
becomes more and more important. So long as one can apply the 
principles of cross-identification, it is easy to isolate the climatic 
effects, for climatic effects prevail over large areas for a short time, 
while topographic influences modify the growth-rates in small areas 
more or less permanently. Thus, as the use of groups of trees becomes 
less and less possible in studying climates more and more remote, the 
separation of climatic from topographic features requires notice to be 
taken of all indicators of environment found in the trees. Without 
any pretension to completeness, the following classification paves the 
way to a future study of this interesting subject. 

EVIDENCE IN INDIVIDUAL RINGS 

This varies in different species, but in the yellow pine a widely 
double ring means a double rainy season, especially if habitually 
recurring. Narrow and indistinct doubles and multiples probably 
mean the same, but in the extreme, multiple rings may refer merely 
to individual storms. 

Average ring-size — This reflects water-supply, which consists (1) 
of rainfall modified by continent, mountain ranges, latitude, and 
altitude; (2) of ground- water, or secondary rainfall, modified by 
drainage contours and kind of soil. 

EVIDENCE IN SINGLE TREES 

Ring-type — Ring-types are: (1) complacent, meaning reasonably 
sure water each year; (2) complacent surges, meaning some slow 



112 CLIMATIC CYCLES AND TREE-GROWTH 

variation in the complacent type; (3) sensitive, meaning limited water- 
supply from lessened rainfall and greatly diminished ground-water; 
(4) shadow or sensitive surges, meaning very great variations in slow- 
growing trees, such as come near the lower (dry) margin of the forest; 
and (5) erratic, meaning immense variations in water-supply, causing 
some rings to be omitted, while others are very large. 

Missing rings — This occurs more often in old age of the trees and 
on very dry ridges, where the moisture is not likely to stay in the 
ground nearby. 

Merging rings — These occur in the pines in dry periods. It does 
not usually mean close grouping. It occurs normally in the junipers 
and pinyons without close grouping. It probably does not usually 
mean close grouping in the big sequoias, but in coast redwood it does 
indicate it. 

Gross rings — Gross rings in the sequoias are understood to mean 
root success with a slight climatic relationship, and to point toward 
certain variable conditions of grouping. 

Lightning scars — Lightning scars are easily recognized in the tree 
section, but not in the core. They are climatic and occur in torrential 
summer-type storms. 

Fire injury — This also is easily recognized in the section. Such 
fires are usually started by lightning and so become climatic in inter- 
pretation. 

CHANGING RING-SIZE 

The change with age is always conspicuous in the diminishing size 
from center to back. Rings growing smaller and then larger to a 
marked degree, in Arizona, mean drought. Badly compressed outside 
rings mean shallow and perhaps denuded soil. Probably soil denuda- 
tion is better indicated when the compression lasts 50 or 100 years. 
Drainage of soil and relief from too much shade are of rare occurrence, 
but when they do come, are recognized by a very considerable change 
that is fairly quick and practically permanent. Reinforced rings mean 
wind whose season of occurrence may sometimes be estimated. 

Climatic variations — Outside the various effects mentioned above, 
the further variations from year to year are mostly climatic. If 
several trees over some area can be cross-identified, it helps in the 
climatic interpretation. But the normal average tree in all ages, 
judged from large numbers of prehistoric beams and many fossils 
examined and measured, is practically free from other disturbances, 
and most of its variations, apart from age changes, can be taken as 
climatic. So also the smoothed curve and its cycle analysis tell a story 
of climatic variations. 



IX. CYCLES 
CYCLE ORIGINS 

It is now generally recognized that certain small climatic variations 
are caused by changes in the sun. The study of tree-growth in this 
volume, and especially its correlation with solar cycles described in 
this chapter, provide the motive for seeking in the sun the real origin 
of larger climatic cycles and in the trees a detailed history of the 
effects of such cycles on organic life. 

SOLAR THEORY* 

Nature of sunspots — The work at the Mount Wilson Solar Obser- 
vatory and elsewhere shows that two-thirds of the sunspot groups are 
dual, with a leader and follower in the direction of daily rotation. 
These are connected below the apparent surface of the sun and form 
the two exposed ends of a partial vortex-ring. The brilliant work of 
Hale has shown that during the recent sunspot cycles the leaders in 
the north and south hemispheres have exhibited opposite magnetic 
polarity and that during the two minima under observation, 1913 and 
1923, the polarity reversed between the two hemispheres. This 
suggests a double sunspot cycle as the fundamental period. Hale 
(1926 to 1927) finds evidence that this polarity results from direction 
of rotation in the lower parts of the spot. Lighter gases in the upper 
and thinner layers of the solar atmosphere are sucked downward into 
the spot. Their direction of rotation resembles usually the rotation of 
storms on the earth and so is independent of sunspot minimum. 

Periodicity theories — No recent advance has been made in explain- 
ing the periodicity of sunspots. The weight of evidence favors internal 
causes; for example, the polarity phenomenon and the " butterfly" 
diagram (by Maunder; it refers to the continued decrease in mean 
latitude of sunspots, as each cycle begins, reaches maximum, and ends) 
both point to internal causes. The possible extension of solar cycles 
back into geologic ages is more agreeable with an internal cause than 
with a meteoric hypothesis, using a swarm subject to perturbations 
and possible dissipation. On the other hand, there is a possibility that 
several cycles will need explanation, and it is hard to think of several 
mechanical pulsations in the sun going on at the same time. Mechani- 
cal disturbance between a dense core and a lighter shell have been the 
foundation of some thought on this subject. Snyder and others have 
been at work on a theory involving atomic energy. This might be 
called chemical pulsation. 

♦Continuing a related topic in Vol. I, p. 84. 

113 



114 CLIMATIC CYCLES AND TREE-GROWTH 

Turner's meteor-swarm theory has the merit of simplicity, since 
it merely becomes an extension of the accretion hypothesis (Chamber- 
lin and Moulton) and offers many choices in periods. Perhaps size 
and shape of a meteor swarm could be invoked to explain crudely the 
butterfly diagram, but it is exceedingly difficult to reach with this 
theory the polarity and rotation of spots. 

Short-period cycles in sunspots — An analysis of monthly sunspot 
numbers since 1750 gave a number of possible cycles, of which 7.9 
months and especially 10.5 months were the best. The former of 
these is the period required by a meteor swarm to pass in a very 
elliptical orbit out to the orbit of Mars and back to the sun. The 
latter is the period a swarm would have with aphelion near the inner 
asteroids. The various periods noted in monthly sunspot numbers 
were found to be multiples of 35 days, which is very nearly the sidereal 
time of polar rotation of the sun (Abbot, 1925, p. 100). But to the 
present time no one has found any satisfactory evidence of planetary 
influence in the formation of sunspots, and this coincidence may be 
accidental. If there were a tidal effect from any planet, it would 
presumably take place twice in the solar rotation. 

Solar rotation — Adams and others have applied the spectroscope 
to solar rotation at different latitudes and find sidereal periods for 
average surface rotation as follows: latitude 0°, 24.6 days; 30°, 26.3 
days; 60°, 31.2 days; 80°, 35.3 days. High levels in the solar atmos- 
phere rotate faster at all latitudes. 

Radiation — Abbot (1925) has done important work upon radiation, 
and now has an accurate record of the solar constant from 1918 on. 
The values passed below normal in 1922 and stayed so during the 
sunspot minimum of 1923. With the beginning of the new sunspot 
cycle this constant has come back to normal. All this change seems 
to be a correlation with the sunspot cycle, with radiation 3 per cent 
above normal at the maximum activity. However, this is subject to 
sudden brief decreases, reaching even 10 per cent, when unusually 
large spot-groups are about one day past the sun's central meridian. 

Ultra-violet radiation — Pettit and Nicholson (1926) have con- 
structed a recorder of ultra-violet radiation (which has a powerful 
effect on plant life), using a thin silver film as screen and producing 
galvanometer deflections by a thermo-couple. The variations follow 
the sunspot activity with accuracy and at the same time exhibit a far 
greater sensitiveness to its changes than found in the solar-constant 
records, reaching perhaps 80 per cent difference between readings at 
times of maximum and minimum sunspot activity. The instrument 
promises to be of unusual value. Perhaps in this way will come the 
solution of a problem formulated years ago on finding the remarkable 
solar records in trees around the Baltic Sea. 



CYCLES 115 

TERRESTRIAL REACTION 

Radiation and terrestrial temperatures — H. H. Clayton (1917 to 
1926), while in the Argentine Republic, began using daily reports of 
the solar constant wired from Calama, Chile, in prediction of weather 
conditions for the succeeding 10 days over northern Argentina. This 
work he is continuing over parts of the United States in collaboration 
with C. G. Abbot, of the Smithsonian Astrophysical Observatory, 
under whose direction the solar-constant measures are made. Such 
prediction is based on direct effects in temperature observed in the two 
weeks or so following changes in the solar constant. Though still not 
accepted as conclusive by some (Marvin, 1925, etc.), the abundant 
tests already made seem to the writer to indicate a positive link in the 
chain of solar influence and terrestrial reaction. The full set of reactions 
as they spread over the earth is doubtless incredibly complex, and 
this appears to indicate something of the way the larger effects begin. 

Radiation and drought — Dr. F. E. Clements (1921), who is work- 
ing on the relation of drought to sunspot numbers, found from the 
rainfall records that when the relative numbers exceeded 80, a drought 
period of two or more years followed in the western United States. 

Electrostatic reactions — The electrostatic charge in the atmosphere, 
earth-currents, and other electric conditions show response to solar 
activity. Dr. L. A. Bauer, of the Department of Terrestrial Mag- 
netism of the Carnegie Institution, has done extensive correlation work 
(1923) and considers that terrestrial magnetic conditions vary with 
" agitated" solar conditions perhaps, rather than merely with extreme 
solar departures from the normal. Dr. Fernando Sanford, at Palo Alto, 
California, is making extensive records of atmospheric electricity and 
earth-currents and finds solar influence in a marked degree. 

Glacial varves — Baron Gerard de Geer, of Sweden (1910, etc., 
1926, 1927), has invented a method of measuring time by the annual 
clay layers, or varves, deposited under water during the retreat of the 
glaciers on the Scandinavian Peninsula and elsewhere. The process is 
given a firm scientific basis by a system of cross-identification of 
layers in different localities, similar to the cross-identification of tree- 
rings used in the present work. By this means he is able to enumerate 
several series of years, totaling some 18,000 since the glacial period. 
Measurements are made of the thickness of the layers, and thus evi- 
dence is found of temperature variations over long periods. The 
absolute date of these clay layers is known only within several hundred 
years. Dr. E. Antevs has applied the process in the valleys of the 
Connecticut and Hudson Rivers and at other points, finding some 4,000 
years in the retreat of the glacial ice up the Connecticut Valley. 
These long sequences of annual layers displaying a temperature effect 
will be of greatest value in studying past climates. 



116 CLIMATIC CYCLES AND TREE-GROWTH 

Antevs's big-tree tests — Dr. Antevs (1925 3 ) has made certain trials 
of the sequoias with reference to their use in studying past climates 
and reached an indecisive conclusion. But this result was anticipated 
from his selection of material and method of procedure. He divided 
Huntington's trees into basin and ridge trees, standardized them, and 
averaged these two classes separately without correcting the dating, 
and then compared the two curves obtained. These curves agreed 
for something like the last thousand years and before that disagreed. 
The difficulty lies in Huntington's incorrect dates (and possibly 
climatic change affecting the two groups differently). Basin trees 
grow rapidly and can be counted easily and so contain few errors, 
while the ridge trees are slow-growing and contain most of the errors. 
Hence, in them the average error would be of the order of twice the 
average error found in his dating, which was ±35 years in the last 1900. 
In view of these details, given in previous publications (Douglass, 
1919, 1922), it should hardly have been expected that undated basin 
and ridge curves would show satisfactory agreement. On the other 
hand, it should be remembered that carefully dated basin and ridge 
sequoias show perfect cross-identification and only differ in the larger 
and more complacent growth of the former due to moist soil, as 
described in publications referred to. 

Ocean rotation effects — One indirect effect of solar causes has been 
studied by Dr. C. F. Brooks (1926), namely, the rotation of the 
Atlantic Ocean under the pushing effect of the normal winds in different 
latitudes. The ocean is a vast storehouse of heat, whose variations 
are thus borne to different shores. The circuit takes some 2 years, 
and thus could originate short cycles of that order of length. Similar 
motion exists in the Pacific Ocean with probably an increased time of 
circuit. 

Closely associated with the study of this ocean movement is the 
work of McEwen (1918, etc.) and Helland-Hanson and Nanson (1920) 
and others. 

Solar cycle and terrestrial seasons — If a solar cycle of 10.5 months 
should exert a precipitation effect on the earth, it would alter the dis- 
tribution of rainfall in different seasons, say in the temperate zone, and 
produce a 7-year cycle. We shall see that a cycle of this length plays a 
part in Arizona tree-growth, but it seems more likely produced by 
corresponding changes in solar activity and not as suggested above. 
If this short solar cycle were double the length given, or 21 months, 
and if its effect did not interfere with the seasons but increased tree- 
growth in each year of its occurrence, then we would find rings alter- 
nately large and small, as has been extensively observed. This is 
referred to in Volume I, page 106. Extended search has been made 
for a 2-year period by taking successive annual differences in growth 



CYCLES 117 

and reversing alternate signs, and plotting. Such curves have shown 
extensive 14-year cycles and half-sunspot cycles. However, on testing 
rainfall records for such period, the weight of evidence favors a broken 
or variable cycle of some 28 months (Douglass, 1915; Clough, 1924). 

CYCLES IN TREE-GROWTH 

CYCLE RELIABILITY 

Definitions — The value of a record of the past is its service for the 
future, and prediction becomes possible as repetition is recognized. 
Repetition may come at irregular intervals, in which case it may be 
wholly accidental; or it may come at nearly equal intervals, in which 
case it constitutes a cycle; or it may come at exactly equal intervals, 
in which case it can be called a true period. 

Short variations — In studying variations of weather and trees, 
the first characteristic observed is the great number of short varia- 
tions. These are usually interpreted as accidental and without sig- 
nificance, for if any large number of annual values be drawn by lot 
and plotted, we shall find in the curve a maximum number of 2-year 
periods, a lesser number of 3-year periods, and so on in decreasing 
rate, all of which, of course, are accidental. So the weather at any 
one locality is full of small variations which it is useless to work 
on at the start. Such variations remind one of waves on water. We 
can picture a combination of land outline and winds which would 
produce an exceedingly complex wave system, but we could probably 
determine the origin of each. We do not get the same bird's-eye view 
in the distribution of weather and we have to class small variations 
as accidental in the sense that they are far too complex to disclose 
their origins at present. But while these variations are now of no 
value in weather prediction, their existence does not prevent the 
existence of certain short-period variations buried in them which are 
not accidental and whose origins are worth tracing. 

Long variations — Accidental and illusive periods decrease in 
probability as the length of the period under test increases. Many 
accidental 2-year and 3-year periods have been found, and even one 
11-year period in numbers drawn by lot, but 20-year periods or over 
have proved extremely rare in accidental sequences. Therefore, in 
the analyses which follow, periods under 10 years have been given 
little weight unless extraordinarily prominent, and as the length of 
period advanced from 10 to 20 years and beyond, more and more 
reliability has been credited to any evidence of periodic variation. 

Criterion of reliability — A criterion for judging the reliability of 
cycles has been suggested which for simple reasons has not yet received 
extensive use. It is applied by taking all the values in a curve con- 



118 CLIMATIC CYCLES AND TREE-GROWTH 

taining the cycle, and twice drawing them out by lot; thus producing 
three curves, of which one is genuine and two spurious. If the genuine 
one can be distinguished from the others by the cycles alone, without 
other marks of identity, then the cycles are there. We can hardly 
yet make application of this to rainfall or tree-growth curves, because 
we do not know (or are just learning) what cycles ought to be there. 
On this account a half dozen criterion tests have resolved themselves 
largely into solving the question of the existence of cycles over 20 
years, for that was the only known mark of identity. That in turn 
depended vitally on the length of the curve under test, for a cycle 
does not carry conviction unless it is repeated five or ten times in the 
record. So the trials on short curves of 50 or 75 years were not suc- 
cessful, while those on curves of 200 years were. It is probable that 
there will be extended use for this criterion, but in the absence of 
better knowledge of the cycles to be expected it has not been thoroughly 
tried and another method of judging reliability has been applied, 
namely, identifying similar cycles in many trees and over wide areas. 

Cycle identification in small areas — In the early use of the cyclo- 
graph it became a matter of interest to know whether cross-identifica- 
tion could be done by cycles. To test this, an early general curve of 
the Flagstaff region was prepared as a standard. An assistant selected 
125-year portions of other Flagstaff trees without letting me know 
to what tree or to what part of the 500 years they belonged. By 
cycles alone each unknown was compared with the standard 500-year 
curve. In the first trial of 10 unknowns, 7 were dated correctly, and 
in the next trial of 10, 8 were dated correctly. In other words, the 
cycles in any given tree in the region specified bear 75 per cent resem- 
blance to a good average cyclogram of that region. Dating by size of 
individual rings is considered to have a reliability of 95 per cent or 
more. This decreased reliance in cycles is due in part to over- 
importance given in those tests to short-period cycles, before their 
unreliability was recognized. 

Cycle identification at 200 miles — Two groups of 8 or 10 trees each, 
one from 40 miles north of Aztec, New Mexico (BMH), and the other 
from 18 miles east (AE), were compared with the Flagstaff records. 
The resemblance in the cycles is extremely close. Periods of 14, 17, 
and 21 years appear in all three groups in practically identical form. 
In this comparison cross-identification by cycles was carried over 225 
miles of country (see Fig. 19 and Plate 9, page 132). 

Cycle identification between Arizona and California — A still more 
difficult test was made between the Flagstaff area and the big-tree 
area. A selection of California trees was made in the following manner : 
The last 500 years of each of 34 trees were plotted and the resemblance 
of the cycles to Arizona and New Mexico cycles was reviewed and 



CYCLES 119 

each tree marked in some way to represent its resemblance. The best 
four (D^4, 16, 20, and 21) were then taken by themselves, having a 
regard both to this resemblance and to their wide distribution in 
California, and the average record of the 4 trees plotted for 2,000 years. 
These plots were slightly smoothed and duplicated so that each one 
overlapped its neighbor half-way, and nearly every part of each tree's 
record appeared twice. In exactly the same manner two other com- 
plete sequoia records were prepared; one was an average of D-3, 12, 
20, and 23, preferred for showing the sunspot cycle, and the second was 
the "best selected" sequoias, with good consistent records. All these 
were prepared by an assistant and marked by him with a reference 
letter, so that I had no idea of the date or identity of any curve. The 
assistant then selected 250 years of Flagstaff tree-records whose exact 
dating was also unknown to me. Comparison was made by cycles 
between the Flagstaff record and the unknown sequoia records. After 
they were completed, all dates of resemblance were looked up, and it 
proved that instead of the six possible correct coincidences, there were 
a dozen apparent agreements, of which six, or 50 per cent, were correct 
and the other six scattering. Thus it appeared that in group averages 
there is a 50 per cent resemblance between the cycles in tree-growth 
in Arizona and those in tree-growth in California, and that a fair 
assurance in cross-dating between these two regions can be reached, 
if one uses, as in this method, enough data from which to obtain a 
convergence of results. 

Advantages of the cyclograph — This instrument, which converts 
mathematical integration into a photometric process, has been used 
almost exclusively in the analyses about to be described. Its extra- 
ordinary advantage is its rapidity of analysis and its flexibility in 
showing the analysis of every part of the curve at the same time in the 
cyclogram or differential pattern, and also in its independence of 
fixed periods, for it shows many periods at once, whether fixed, variable, 
or broken. 

Disadvantages of the cyclograph — The chief disadvantage is that 
in its present form one can not assign quantitative amplitudes. This 
could be done by passing the photographic negative of the cyclogram 
under a recording photometer, of which there are several types suffi- 
ciently accurate. The amplitudes could be derived easily from the 
galvanometer curve. 

PERIODOCRITE 

Professor C. F. Marvin, chief of the United States Weather Bureau, 

has suggested (1921) the use of a process which he names the period- 

ocrite. It simply solves the question : does the application of a given 

cycle reduce the probable error? If so, the use of the cycle is justified. 

9 



120 CLIMATIC CYCLES AND TREE-GROWTH 

ZONE CENTERS AND THEIR MEAN CURVES 

The material collected over western areas has opened such a field 
for immediate development that the contents of this chapter can only 
be regarded as a transition rather than a conclusion. Such progress 
and results as have appeared to date will be given, but they must be 
taken as subject to revision at a later time. 

Cross-identification — Introductory to the comparison of smoothed 
curves, it should be recalled that cross-identification by individual 
rings is the exact and reliable method of comparing curves over large 
or small areas. In the western States it is found to grow easier and 
more reliable as the climatic stress of the arid regions is approached, 
that is to say, such dating is highly satisfactory within the Arizona 
region, which extends to the Rio Grande on the east and the coast- 
line on the west. It is fairly satisfactory between Arizona and Central 
California, as also from Arizona to the central Rockies, but the northern 
States, with a very different tree-record, do not cross-date with Arizona. 
An electrical instrument is now under construction which it is hoped 
will reduce this cross-dating by individual rings to mechanical quanti- 
tative measurement. When that is accomplished it will perhaps be 
possible to express similarity between groups by a single coefficient. 

Comparison of smoothed curves — The crests of these curves give 
the phase or epoch of maximum of the various cycles which may not 
be the same in different regions. Two results appear in this curve 
comparison, namely, first, a real separation into the three zones, and 
second, a latitude effect in which there is much more similarity east 
and west between the zones in their southerly or drier parts, than in 
the northerly moist latitudes. 

Flagstaff area mean curve — In consequence of the southern sim- 
ilarity just mentioned, the Arizona area could be regarded as exceed- 
ing the others in size, for Pine Valley and Charleston Mountains show 
similarity on the west, and Basin Mountain, Aztec East, and Santa 
Fe repeat Arizona features on the east. However, the Catalina and 
Santa Rita Mountain groups near Tucson show marked differences. 
The Flagstaff area presents an excellent central homogeneous collec- 
tion of curves from the Grand Canyon to the Rim and Cibecue, a 
distance of 175 miles (GC, FV, SH, NE, FL, FLU, RL, and J). These 
curves have been combined together graphically and the mean result, 
1702 to 1920, is shown in figure 18, upper curve, page 128. This curve 
is important, because it is probably a better rainfall curve than those 
of the other zones. We note that shorter periods are largely smoothed 
out, except parts of a 7-year cycle. A period of 21 years (with lesser 
14-year effects) strongly dominates, thus agreeing with a result reached 
in 1908 and referred to in the previous volume (p. 104). The sunspot 
cycle with its half and double appear in the early parts of the curve, 



CYCLES 



121 



as also 8.5 and 17 year cycles. Further discussion will be found below 
under Solar Records in Tree-Growth, page 125. 

Pike's Peak area mean curve — The groups in the Rocky Mountain 
zone cover a smaller area than those in the other zones. Thus the 
area represented by the mean curve is limited to the east slopes of 
Pike's Peak in the vicinity of the Cog Railroad. The homogeneous 

























l.b 
1.0 

0.5 































































1700 



80 



a 0.5 



















j~, s 


\ /\ 


r\ 


/\ 


















/*"■" \s \/ \y v \ 



~ 1300 10 20 30 40 1850 60 70 80 90 1900 10 1920 

YEARS 

Fig. 13 — Pike's Peak area mean curve, PPM ; average of six groups, standardized 

and smoothed 

collection of groups includes six, PPB, HNT, LNT, C, ST, and BDF. 
The Laramie group and those from Santa Fe and the Aztec region are 
similar, but not quite enough like the central collection to be included. 
The mean curve of the six named is shown in figure 13. It appears to 
show strongly a 5, 10, 20 year cycle and a triple sunspot cycle divided 
into halves and quarters (that is, an 8, 17, 34 year cycle). 

Sierra Nevada mean curve — The distribution of groups in this 
zone is better than in the other zones. From The Dalles in northern 



4.0 










































2.0 











































1700 10 20 30 40 1750 60 70 80 90 1800 



4.0 






















































2.0 























































a 
a 
< 



I8C0 10 20 30 40 1950 60 70 80 90 1900 10 20 1930 

Fig. 14 — Sierra Nevada area mean curve, SNM ; average of four groups, standardized 

and smoothed 

Oregon to Pine Valley near San Diego the nine locations are fairly 
well spaced. There is pronounced similarity in the smoothed curves 
in all of these except Klamath Falls and Pine Valley, but the best 
agreement occurs between those in the Sierra Nevada Mountains from 
Calaveras to Mount Wilson and the mean curve is the average of 
these, namely, CVP, BC, EP, and W groups. It is given in figure 14. 



122 CLIMATIC CYCLES AND TREE-GROWTH 

It will be noted that this inner group does not include the trees from 
San Bernardino Mountain, which show a remarkable double sunspot 
cycle. These were not included because they seemed to represent an 
extreme condition of some sort which should be studied by itself. 
A preliminary analysis of the Sierra Nevada mean curve shows a 5, 
10, 20 year cycle, very strong in early half (1700-1800), a 5.8, 11.8, 
22.8 year cycle, strong in the late half (after 1800), and a 7±, 14-year 
cycle growing strong in the late half. 

METEOROLOGICAL AREAS: THE PROBLEM OF COMBINATION 

Use of trees in outlining meteorological areas — Very few weather 
records reach 100 years in length, and they are apt to be at widely 
scattered places, subject to different conditions, such that the records 
can not be combined advantageously, but a forest gives a vast number 
of long records in some definite region. With proper care we do not 
need to mix records of different types. No doubt we have exaggera- 
tions, and in young trees we have a smoothing-down of variations. 
In terms of thermometer and measuring-rule, our values are not of the 
highest precision, but as seen from the viewpoint of actual growing 
vegetation the tree record is hard to surpass. 

Disadvantages — While we have as yet no substitute for the length 
of record given by the trees, the chief difficulty is that the reaction 
of trees to certain weather elements that physical conditions make it 
easy for us to measure (temperature, precipitation, etc.) is not every- 
where proportionate to these causes and under certain conditions may 
be fundamentally changed, as, for example, in the reaction to moisture 
in wet climates. The differences between the zones as shown below 
is perhaps in part an illustration of this. That investigation is as yet 
unfinished. 

Problem of combination — Meteorological reports are collected in 
various districts which are political subdivisions, and are not outlined 
by weather conditions. When the student begins to combine areas in 
order to get general averages, he is confronted at once by the problem 
of combination, for before combining he has to find out what areas 
it is safe to combine without losing valuable material. The error of 
too large combination kept meteorologists from admitting solar effects 
in weather for a score of years. 

Tree-record combinations — In work with the western groups the 
general experience has been that trees in the same forest are very 
much alike and may be combined without loss, if care is taken to use 
trees exposed to similar conditions of soil-moisture. Thus the groups 
were formed. In combining groups the guides have been: (1) geo- 
graphical outlines of zones, (2) obvious similarity in smoothed curves 
which probably is equivalent to phase similarity in cycles, and (3) 



CYCLES 



123 



obvious similarity in cycle-length. The relations between phase 
and zone have been described above in connection with smoothed 
curves. The relations between cycle-length and zone are now under 
consideration. 

Effect of combination on cycles — In a previous chapter the cycle 
analysis of each group was given, some 42 groups. Here we have a 
large number of widely scattered small units. The dominance of 
certain cycles in these zones seems very significant. When we com- 
bine the curves and use the mean curve for a homogeneous area, the 
cycles in this general curve are reduced in number, giving a few 
powerful ones and only traces of others. 

Present importance of small units — It is felt that the group is still 
the important unit for analysis, and though more general combinations 
are illuminating and helpful, the fundamental information is in the 
group. 

CYCLES IN WESTERN ZONES 

Arcigram — In a periodogram the ordinates give the amplitudes of 
the various periods in a given curve. In the summaries below the 
ordinates give the number of occurrences of each cycle-length over a 
given area, and for the present the word " arcigram" is used to refer 
to this kind of a diagram. The distribution of cycle-lengths in the 
three western zones is shown in figure 15. 

Derivation of ordinates — The number of groups in the three zones 
is nearly the same: Arizona, 14; Rockies, 15; Coast, 13. In the first 
plotting of figure 15, the ordinates consisted of the number of occur- 
rences of cycles in each half unit of period; for example, those between 
12.0 and 12.4 inclusive, and those within 12.5 and 12.9. But in the 
original analyses three weights had been assigned, and in the curves in 
figure 15 each occurrence is counted one, two, or three times as it was 
assigned weight. This inclusion of weights made no essential change 
in the curves. 

Western area cycles — The cycle occurrences in the three zones 
were counted and plotted separately, and the important characteristic 
appeared that the cycles are much the same in each, with somewhat 
different emphasis. This similarity, as shown in the figure, is evidence 
in favor of the approximate values here given, which appear to be very 
nearly simple fractions of 34 or 35 years, as can be seen in the following 
list: 



6.8 | 

7.6 (rare) T \ or 

8.6 i 

10.2 f 

11.2 to 11.7 i 

14.2 | 



17.2 £ 

20.5±1 for 

22.5 to 24.0 f 

25 + (rare) | 

28±1 ft 

31± (rare) f 

35± 1 



124 



CLIMATIC CYCLES AND TREE-GROWTH 



This relationship of western cycles only appeared in recent work 
and is still provisional. It may be real, but, on the other hand, there 
may be some preferential selection by the analyzing instrument or the 
observer, in spite of great effort to get rid of such errors. It should be 
added that the cj'cle given as 20.5±1, really covers the interval from 
19 to 21, and could have interpretations at 19, 20, or 21 years. The 
brief study, given later, of solar records in the long Flagstaff tree- 
records, throws a little more light on this.* 



5 6 7 3 10 II 12 13 K 15 16 17 18 19 20 2; 22 23 24 25 U 27 28 29 30 31 32 33 34 3b ?G 37 38 39 40 




5 6 7 8 3 10 II 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 3940 

Cycle length in years 
Fio. 15 — Cycles in western zones 



Arizona zone — The Arizona zone is distinguished by the absence 
of 8, 10, 11, and 17 year cycles and the great dominance of 14 and 20 
years. Its double sunspot cycle averages a little over 23 years. 

Rocky Mountain zone — Cycles of 10, 11, and 14 years are largely 
lacking. The 8+ and 17 year cycles have more prominence here than 
in the other zones, but the 20 and 23 year cycles are the strongest in 
the zone. 

♦Recent independent tests sustain these results. 



CYCLES 



125 



Coast zone: — Cycles 17 and 20 years are largely lacking. The 10 
and 11 year cycles are stronger here than in the other zones, but the 
23-year cycle is the strongest in this zone. 

Zone summary — The characteristics of the three zones are brought 
out in the following list : 



Zone 


Prominent 


Deficient 


Arizona 


14 20 years 
8 17 
20 23 
10 11 
14 23 


10 11 17 years 
10 11 14 

17 20 


Rockies 


Coast 





Sequoia cycles — The above summary deals almost entirely with 
the yellow pine; for comparison the cycle analyses of some 32 sequoias, 
from 1400 on, have been combined into one arcigram which agrees 




7 B 9 10 II 12 13 14 IS 16 17 16 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 39. 

Cycle length in years 
Fig. 16 — Sequoia cycles 

with the pines in the coast zone in giving prominence to cycles of 10, 
11, and 14 years, but differs from them in having a very prominent 
20-year cycle with lowered emphasis on the 23-year cycle. This 
includes the entire list of sequoias in the General Grant Park region 
without selection of any kind, and indicates more resemblance to the 
Arizona reaction than appears in the pines of the same area. 

SOLAR RECORDS IN TREE-GROWTH 

Historical confirmation — From the start the sunspot cycle was 
sought in the Arizona pines, and during large portions of their growth 
it seemed perfectly evident, but for scores of years near 1700 it failed 
entirely; in 1914 the writer very nearly gave up the idea that the trees 
show it. In 1919 (Volume I, p. 102) the cycle record was given with 
the statement that from 1660 to 1720 the sunspot curve " flattens out 
in a striking manner," and again, "the sequoias show strikingly the 
flattening of the curve from 1670 or 1680 to 1727," and again, "it 
seems likely that the sunspot cycle has been operating since 1400 a. d., 



126 CLIMATIC CYCLES AND TREE-GROWTH 

with some possible interference for a considerable interval about the 
end of the seventeenth century." Early in 1922 a letter was received 
from Professor E. W. Maunder, of England, calling attention to the 
prolonged dearth of sunspots between 1645 and 1715, and saying that 
if there were a connection between solar activity and the weather and 
tree-growth, this extended minimum should show in the weather and 
in the trees. On receipt of the letter, this period was immediately 
recognized as the interval referred to in which there was entire failure 
in attempting to trace effects of the well-known solar cycle. The 
sequoia record for the last 500 years, as summarized in figure 33, page 
103, of the previous volume, confirms minutely the result. So also do 
the Vermont hemlocks and other tree-records. 

Dearth cycles — In 1922 or before it was noticed that when the 
11-year cycle disappeared from the trees near 1700, two other cycles, 
one of 10 or 20 years and the other of 7 or its smaller multiples, became 
prominent in its place in the Arizona pines (see Plate 9 and Fig. 19). 
Soon after, it was noticed that the Vermont hemlocks and the sequoias 
of California show similar change at that time. And then it was 
observed that these three cycles appear generally in the western trees; 
they are, first, the known sunspot cycle of about 11£ and its double 
of 23 years; second, 10 or 20 years; and, third, 7, 14, 21, or 28 years. 
These three cycles, with others mentioned below, have been confirmed 
in the present study of the 42 western groups. There is some reason 
to think that all of these cycles come from the sun, for at different 
times the sunspot cycle itself has changed to one or the other of them. 
For example, from 1748 to 1788 there were four complete cycles of 
close to 10 years each; and from 1788 to 1837, 49 years, there were 
three complete cycles of about 14 years each and one of 7. It seems 
at least likely that these other two cycles, found in western trees with 
extraordinary persistence, are also of solar origin. 

Wet and dry climatic effects — In this study of cycles in the western 
yellow pine it was found that in this dry region, where trees are 
specially sensitive to rainfall, they show, besides other cycles, a double- 
crested 11-year variation, just as the rainfall itself does, but in the 
moist coastal regions this solar cycle has more often a single crest 
like that of the sunspot numbers. This agrees with the result of 10 
years ago, in which the wet-climate Scotch pines of North Europe, 
especially near the Baltic Sea, showed a direct single-crested cycle 
having a remarkable resemblance to the curve of sunspot numbers 
(Volume I, p. 77). Their growth gave the solar changes with an 
accuracy exceeding that of any trees of the southwestern area. (See 
S-14 in Plate 9.) This remarkable solar record is a wet-climate 
phenomenon, but it is not yet clear just what causes its accuracy. 
It seems probable that these trees follow the sunspot cycle more 



%(* 



Carnegie Inst, of Wash. Pub. 289, Vol. II (Douglass) 




Spruce, S-14, from South Sweden, showing sunspot cycle; wet climate reac- 
tion. Dots give dates of sunspot maxima beginning with 1830 



CYCLES 



127 



closely than do the weather elements in which they live, and it is 
perhaps safe to repeat the suggestion made by the writer in 1922 that 
there may be some more direct line of cause and effect from the sun 
to these trees than we have taken into account, such, for example, as 
radiation (possibly of short wave-length), that is especially favorable 
to trees growing generally under cloudy skies. In tree-groups along 
the Atlantic coast of this continent, the 11-year cycle is also prominent, 
but it has a phase displacement of 2 or 3 years. 

SOLAR CYCLES 
Eleven-year cycle in long Flagstaff record — Combining the long 
Flagstaff century curve beginning in 1285 with the Flagstaff mean 



usr 




1500 10 20 30 40 1550 60 70 80 \ ,' ' 90 1600 



I.S 




A 










j\ 


i 


\ 




Ul 


/' 


\J 


"W> 


^L A 


A/ 


\ / 


\ 


r 


\r 


^N/\ 


/ 






y\j 


\j 


Y 


\ 


/ 


V 




n* 














\ 


/ 







*600 10 20 30 40 1650 60 70 80 90 1700 

YEARS 

Fig. 17 — Flagstaff century curve, FLC, a.d. 1285-1700; standardized 
and smoothed 

area curve from 1700 on, one has full 625 years of sensitive tree-growth 
(see Figs. 17 and 18). To this a superficial graphic analysis has been 
applied with a number of interesting provisional results. The first 
test deals with the extended half-sunspot cycle in the early Flagstaff 
curve, found in 1908 and shown on page 102 of the previous volume. 
The first hundred years of our present curve is made up of several 
radials of one tree which had suffered a considerable injury in 1295. 
It begins to show the cycle with certainty about 1320. The cycle 
continues without interruption till 9 other trees join it between 1385 
and 1419, during which time it is discordant, probably in part from 
poor merging process in adding the new trees. Then it continues 
without discord till 1541, 1550, and 1566-67. After that it is in 



128 



CLIMATIC CYCLES AND TREE-GROWTH 



accord again till 1617, and from there on it decreases its accuracy, and 
the variations typical up to that point disappear from the curve. 
The curve from 1700 on shows much less of the sunspot variations, 
but in the Grand Canyon group, one of its components, and others 
also, the half cycle shows well from 1850 to the time of collecting and 
with almost the early regularity. Brief calculations show that the 



L5 
























/ 


v 




A 












1 '° 
1.5 


j 


y 


Va 




,A 




/N 






A 


-V 




\ 


A/ 


r % 


\J 




S 


/V\> 


1 \ 


V 






\j 




\s 




VJ 


/ 




2 i.o 

. 1.25 

3 l0 
























/> 






A 


K ^^- 










A/ 


\J 


v 




A 


r 


k y\ 






A 


'V 




V- 


V 


j 


\J 


°\ 


S\ 


L -^ 






















K/^ 


\ 



1800 


























1.0 


/ 


w 


















/ 


'^v 


















1.0 

0.75 
1.0 


J/ 








































y 


k 


















/ 


\y^ 




















V 





















1900 



1950 



60 



80 



Fia. 18 — (1) Flagstaff area mean curve, FAM; average of eight groups, 
standardized and smoothed; (2) synthetic curve; (3) residuals 



long variation in the earlier curve agrees exactly in phase with the 
recent years, and so we find through practically 600 years a mean 
value of the sunspot cycle of 11.30 ± 0.02 years. From the correlation 
diagram already referred to on page 104 of Volume I, we see that the 
most direct relation between the double-crested growth-curve of the 
above stated length and the single-crested sunspot curve is that a 
growth maximum occurs at the time of a sunspot minimum. On 



CYCLES 129 

plotting in the early times of sunspot maxima and minima, according 
to Wolfer, we find that the telescope was invented and spots observed 
just in time to show that it has always been the same maximum of the 
double-crested tree-cycle that came at sunspot minimum. This in 
itself is an interesting fact, for it intimates that the 11 -year cycle can 
be called a well-defined period which the sunspots do not always follow 
exactly. Apparently, the 11.30-year period and the sunspot cycle are 
two different things. 

Seven years and multiples — There is further information in the 
tree-records which perhaps adds light but does not fully solve the 
solar puzzle. The Flagstaff area mean curve in figure 18 has some 
large variations which are roughly solved without difficulty. A 21- 
year cycle is very prominent and a 14-year and a 7-year cycle easily 
evident. These values seem to be very close to 7.0 and its multiples. 
The time of maximum of the shorter periods is about 1910 and for the 
21-year period possibly 4 years later. This, however, is not a rigorous 
solution. The amplitudes (from the mean value) increase from 5 or 
10 per cent in the 7-year to double that in the 14-year and triple in the 
21-year periods. This group of multiples of 7.0 becomes evident about 
1663 with a large maximum of the 21-year type. It rather fails in the 
1680 's, but after 1700 comes in regularly. Its beginning is thus con- 
nected with the great dearth of sunspots described by Maunder (1922). 
A single maximum of this apparent type occurred in 1479. 

Nine-year-plus cycle — A very crude graphic synthesis of these 
periods has been made (and extended to 1980) whose resemblance to 
the original curve is fair. This is shown in the central curve in figure 
18. So a set of residuals between it and the original was plotted 
and two interesting features appeared, as shown in the third curve of 
Figure 18. A set of crests came in 1747, 1758, 1766, 1777, 1786, and 
1794, all of which except the last came close to the sunspot minima 
during that unique interval when the sunspot cycle averaged about 
9.3 years in length. (The minima were 1755, 1766, 1776, 1784, 1797.) 
The length derived from these crests is 9.4 years, which thus gives us 
a terrestrial cycle related immediately to a definite solar cycle. It is 
possible that the fairly common climatic cycle of 19 years is the double 
of this solar cycle. From 1800 to 1880 the agreement between the 
natural and synthetic curves is good, except for the extreme minimum 
growth in 1847 and 1880, 33 years apart, and from 1880 to 1905 the 
7-year cycle is practically absent, reappearing again subsequently. 

Historical changes — In a general way it is safe to say that the 
sunspot cycle and its double and triple values are very common. The 
double value has persisted in Arizona for 600 years with interruption 
from 1630 to 1850 or thereabout, and in some North European locali- 
ties it shows for the last century and a half covered by our tree groups. 



130 CLIMATIC CYCLES AND TREE-GROWTH 

The triple period, essentially Bruckner 's cycle, has operated in Arizona 
for the last 200 years and in Norway for 400 at least. Western zone 
cycles are largely its simple fractions. A hundred-year cycle is promi- 
nent throughout the 3,000 years of sequoia record, and a cycle of 
about 150 years shows in the 600 years of yellow pine. It seems fairly 
probable that the 11-year cycle can be judged by the variations in its 
double value, which in some cases is more easily traced through long 
periods. A very incomplete review of the sequoia record suggests that 
from 1300 b. c to well after 1100 b. c, the 11-year cycle was strongly 
developed. Near 300 b. c. it was again apparent, though not very 
conspicuous. During the first two centuries of our era it was again 
highly dominant. It reappeared from 375 to 475 and from 600 to 650 
and was operating during much of the ninth century, though mixed 
with other cycles. Then it appears only occasionally until after 1300, 
when it again becomes fairly continuous, except for the changes in 
the seventeenth century (1633 to 1712) above noted. This is a pro- 
visional report and will, without doubt, receive changes when the 
sequoia records are minutely examined for the purpose. 

Climatic patterns — From this study of the geographical and his- 
torical distribution of climatic cycles it is inferred that they are 
climatic patterns made up of interferences between a number of simple 
fractions of a few fundamentals, traceable to solar influence. This 
form of interference seems to produce pseudo-cycles which vary with 
the phase relationship of the fundamentals and whose resulting tem- 
porary character has always been a stumbling-block in the way of 
investigation. 

CYCLOGRAMS 

An analytical review of some of the cycles mentioned in this chapter 
is given in Plate 9. To one who understands the extent of information 
in the cyclogram, and, if I may add, the spirit of this information, that 
is, its frankness in showing its own accuracy or error, these figures 
visualize the facts in a most compact and convenient way. 

Cycle identity across 200 miles — The first three cyclograms, taken 
in immediate succession on the same plate, show an analysis at a 
period of 18.1 years (represented by the thread) of the Flagstaff curve 
and the two points near Aztec in northwest New Mexico, from 1700 
to about 1910. The most conspicuous alignment is the 21-year cycle, 
but 17- and 14-year cycles also usually show. The similarity in general 
pattern is apparent at once. This is evidence of the reality of the 
cycles and of their climatic significance (page 118). 

Dearth cycles at A. D. 1700 — The Vermont hemlocks give an analy- 
sis shown in cyclogram 4. Here the Bruckner cycle dominates from 



CYCLES 131 

1650 for more than 100 years, accompanied by a 28-year cycle, of 
which traces are found to continue even in the late half (1775 to 
1900), in which the sunspot cycle and its double prevail. The latter 
condition extends from about 1750 to the present time. In the early 
half also a 20-year cycle is faintly shown by a distinct alignment, as 
marked in the explanation diagram. So in this record also we find the 
11 -year cycle replaced by 20- and 28-year cycles during the dearth 
of sunspots near 1700 and for a brief time after, that is, to about 1750. 

Cyclogram No. 5 gives an analysis of the sequoia record in four 
trees, D-3, 12, 20, 23, which were selected for their excellence in show- 
ing the solar cycle. The interval covered is the 400 years from 1450 
to 1850 at a set period of 23 years, represented by the thread. The 
change from the double sunspot cycle to the 10, 20-year cycle took 
place near 1630. At about 1700 all three cycles (10, 20, 23, and 28) 
begin to show. In the last half century or so, the 20-year cycle domin- 
ates, which agrees with the "arcigram" of the sequoias mentioned a 
few pages above. The dearth cycles (20 and 28) were forming by 1550 
more or less, and they are the ones which prevail during the absence of 
sunspots near 1700. 

The Flagstaff evidence of dearth cycles is shown in cyclogram 6. 
Here it is easy to trace the double sunspot cycle from 1400 to its 
end near the center at 1650. The 14, 28-year cycle enters at about 
1550, but after 1700 it is practically lost, due to smoothing and the 
great dominance of the 21-year variation, which continues to the end. 
The 35-year variant begins not far from 1700. This cyclogram was 
taken in 1921 from the original Flagstaff group, smoothed by 5-year 
overlapping means; all the others shown are from original unsmoothed 
plots or from Hanned curves. 

Flagstaff long record — Cyclograms 6, 7, and 8 show the analysis 
of the long Flagstaff record (500 years used here) at three different 
settings for cycle-length, 22.1, 14.0, and 7.0 years. The first, as just 
described, shows the main features of the sunspot cycle to 1650 and 
the 21-year cycle since 1700. The second gives more detail. The 14- 
year cycle enters near 1500 and continues to the end. The 11-year 
period, often double, may be traced from 1400 to well after 1600. 
A 9- to 10-year cycle is evident from about 1650 to 1775 or so. Thus 
the "extra" cycles (10 and 14) are clearly found connected with the 
dearth of sunspots about 1700. 

The Flagstaff analysis at 7.0 years is given in cyclogram 8, but the 
numerous short cycles shown are not so important and sure as the 
longer ones already described. 

Arizona drought cycles — There is no doubt that a demonstration 
of the periodic action of droughts would be of great value to the South- 
west. Accordingly, in 1925 a "skeleton" plot of Arizona droughts, 



132 



CLIMATIC CYCLES AND TREE-GROWTH 



shown in the trees, was made and analyzed. The major dry periods 
came at 1440, 1580, 1735, and 1880 to 1900, or an average of about 
150 years apart. Also, the single tree which gives a record beginning 
at 1285 shows a great depression at 1295 to 1300, which conforms to 
this 150-year spacing. Thus the major droughts give a cycle which 
was long since (1914) noted as occurring in the Arizona record. Cyclo- 
grams 9 and 10 show analyses at 14.6 and 20.2 years as the best to 





1700 1900 


1 

Flagstaff 


17 




< 




17 


00 , l» 


JO 


2 








Aztec 


/7 






East 




< 




"f 








1 


700 19 


00 


3 














Basin Mtn 




• %^* 








*#^« 


* 




»/ 




^A. 



18.) 



IS. I 



Cycle identity across 200 miles 

1650 



4 

Vermont 
hemlocks 




Dearth cycles at 1700 A.D. 




400 


me 


- 5- <- 





Flagstaff cycles near 7,l4and 22 

1442 1580 1735 1900 



M \* »« 4 # ,,(* ****** 



/*x 



10 



»>", 



I #£«««* 


^ « \»\ » <0 


»V • iN * 


s w »W « « V 


,«*<» <(M*«» 


/* V* WW ft(, #> 


tfV #>#* 


^ « \«« «»v\Ki 






Arizona drouth cycles 



Fig. 19 — Details of cyclogram patterns in Plate 9 

cover this 575-year lapse of time. These cycles are near the 14.0 
and 21.0 values and may be identical. It will be seen that there is a 
tendency to group the droughts at intervals of something under 50 
years. This could be 42 years, the interval at which 14- and 21-year 
cycles have their major effect on each other. Probably the 150-year 
effect emphasizes whichever 21-year multiple is nearest, with some 
modification from the 14-year cycle. 



0^ 



Carnegie Inst, of Wash. Pub. 289, Vol. II (Douglass) 




1, 2, 3 — Identity across 
200 miles 



6, 7, 8 — Analyses of 
Flagstaff pines 




4, 5 — Dearth cycles 
near 1700 a.d. 



9, 10 — Cycles in Arizona 
droughts 



Cyclograms 
Explanatory diagram on opposite page 



10 



CYCLES 133 

CYCLES AND CLIMATE 

Three major lines of interest have emerged in this study of cycles 
as it has developed in this chapter. The first was the distribution of 
cycles over western areas in approximate simple fractions of 35 years 
(or perhaps the triple sunspot value of 33.94 years) ; the second is the 
history of cycles in the long Flagstaff record and their agreement with 
solar changes, thus throwing light on solar history; the third now to be 
considered is the problem of prediction, which depends directly on the 
climatic significance of the cycles previously discussed. Their climatic 
character seems open to no reasonable doubt. Dating and prediction, 
the backward look and the forward look, both depend on a knowledge 
of the historic and geographical distribution of these cycles. In each 
it is better to test out a small locality first, such as the Flagstaff region, 
in order to avoid the complexities which arise over too large areas. 

First caution: Interpretation differs with locality — The Arizona 
trees respond closely to a definite weather element, rainfall, the most 
important element in the prosperity of the country, but in the moist 
areas this direct response decreases and even disappears. Hence, the 
first caution in this process is that we must not assume relationships 
similar to those in Arizona in any given place until that place has been 
thoroughly investigated. 

Second caution: Cycle changes not understood — The second 
caution is very important. Until we know the physical cause of cycles 
we can not say how long a mechanical repetition will last, for it may 
break down at any time. This is well illustrated in the solar changes 
shown in the long Flagstaff record. For hundreds of years the 11 -year 
cycle was dominant, and then in the middle of the seventeenth century 
it faded out and gave place to others, and we do not yet know the 
reason. Until we know the reason we can not be sure it will not happen 
again in the near future. Fortunately, we have the long-lived sequoia 
for testing out secular changes. The best results from it at the present 
time were given in a historical summary above. 

Variable star analogy — There are several variable stars which are 
dominated by different periods for irregular intervals of time. One of 
the best is SS Cygni, which has been observed carefully for more than 
30 years. It is not visible to the naked eye, but by telescopic observa- 
tion has been found to rise suddenly from the twelfth to the eighth 
magnitude at intervals of 50 or 60 days, more or less. Alternate 
maxima are often of different length, reminding us of alternate sun- 
spot maxima. Then without warning the period changes. Dr. Leon 
Campbell, of Harvard College Observatory, has given me data and 
for years I have tried to find the rule which governs these changes. 

Third caution: Cycle subdivisions — The splitting of cycles that 
may differ in different localities causes an uncertainty in place of 



134 CLIMATIC CYCLES AND TREE-GROWTH 

maximum or minimum. Consider, for example, a yearly curve of 
temperature, low in winter and high in summer. Impress upon this, 
as we have in Arizona, a summer rainy season which lowers the daily 
averages and produces a slight summer minimum. The maximum is 
split and driven each way, but owing to the lag in effects the higher 
maximum comes in June. If a cycle is split we need to know whether 
it is the maximum or minimum that changes. If only one changes we 
get a double-crested curve and if both maximum and minimum split 
we get a three-crested curve. In the 120 or 130 analyses of western 
groups, certain cycles, obviously the same in each case, were sometimes 
found single, sometimes double, and very rarely triple. Hence, it is 
evident that the comparison of dates of maxima and minima is a 
complicated process. 

Fourth caution: Interference cycles — If some tree cycles arise, 
as is possible, from an interference between some external short cycle, 
say 10.5 months, and the annual seasons, then it is evident that the 
time of maxima would not necessarily be the same in different geo- 
graphical locations, for the time of favorable season is different. Com- 
parison between the northern and southern hemispheres would be 
needed to settle such cases, for similar conditions in the two hemi- 
spheres would reverse the cycle. A single curve from Tasmania 
suggests a split 35-year cycle, with major maximum about 1891 and 
minor maximum in 1908. In the early Arizona curve the maximum 
of the 35-year cycle was put about 1900, but in the recent study of 
western groups this 35-year cycle is usually split into two 17-year 
cycles whose maxima come in 1892 and 1909, thus agreeing with 
Tasmania. 

Fifth caution: Cycle centers — In the western zones it was found 
that each zone had a homogeneous central area with scattering varia- 
tions about it and that intermediate points, such as the Charleston 
Mountains, partook of the variations of each zone near it. It is not 
impossible that we shall find several more central homogeneous areas 
from which certain typical effects spread out. It is evident that in 
such conditions many intermediate places will have badly mixed 
conditions, so that prediction of any kind will become additionally 
difficult. 

Flagstaff area synthetic curve — The mean curve covering the area 
from the Grand Canyon to the Rim shows very excellent similarity 
to the individual curves composing it, but many of the short periods 
have disappeared and multiples of 7.0 years are left prominent, 21 
years being by far the strongest. Residuals between the synthetic 
curve and the real growth-curve show a 9.4-year cycle in the latter 
part of the eighteenth century. Crests are too high (in the natural 
curve) at 1793 and 1891 and the minima at 1847 and perhaps 1880 



CYCLES 135 

are too low to be accounted for by the synthetic curve. The 7-year 
cycle was almost absent from 1880 to 1905. Yet on the whole there 
is a good deal of similarity. The prolongation of the synthetic curve 
shows a small depression near 1927 and deeper ones at 1942 and 1947. 
The interval during the 1930 's has high ordinates with an unimportant 
depression at 1933. It is possible that the 1947 depression may 
resemble the one of 1847 and be rather extreme. During the 1950 's 
the curve is again high. High crests occur at 1937 and 1953. It is not 
expected that this is entirely right, but the details are given here in 
order to assist ultimately in finding the true variations. 



10 



SUMMARY 

The foregoing book includes the following descriptive matter : 

1. The technique of collection and preparation of material brought 
up to the latest development, with special studies of trees and rings. 

2. New instruments constructed and used, namely, the tubular 
borer, the automatic plotter, the longitudinal plotter, and the White 
cyclograph (periodograph without the attachment for producing the 
periodogram) ; the cyclogram is here definitely used in place of the 
periodogram. 

3. The collection of long tree-records including (a) sequoia groups 
from Calaveras and Springville, (b) coast redwood groups from Santa 
Cruz and Scotia, (c) a 640-year yellow pine, and (d) much archaeo- 
logical material for constructing a very long yellow-pine growth record. 

4. The collection and measurement of 305 yellow-pine ring records 
in 42 groups, from 10 western mountain states, representing the area 
from the eastern slope of the Rockies to the Pacific coast and extending 
from the Mexican border to the latitude of the Columbia River. 
Practically all these trees were standardized individually before obtain- 
ing group averages. 

The results obtained and described are as follows : 

1. All the sequoia groves from Calaveras to Springville give the 
same climatic record and can be cross-identified throughout their 
records; the northern groves are more complacent in ring- type. 

2. The coast redwoods, carefully selected and most carefully com- 
pared, could not be cross-identified and therefore are not used. 

3. Ten-inch boring tests every 20 feet on a sequoia 265 feet long 
and 15 feet in diameter, which fell in 1901, gave almost perfect simi- 
larity throughout in the heartwood, but very considerable differences 
in the water-soaked sapwood. The problem of change in ring-size 
is opened. In living trees the change is probably very small and con- 
nected with conservation of moisture, sometimes possibly retroactive 
on the rings. 

4. Topographic studies show that soil moisture is a strongly con- 
trolling factor in ring-type, both in sequoia and yellow pine. Soil- 
moisture gradient below the trees could be used as an indicator of ring 
characters. 

5. Trees at higher altitudes and at higher latitudes (than about 
32° N.) show more complacent rings. 

6. Close grouping in the pines and sequoias produces objectionable 
alterations in rings only under extreme conditions and can be avoided 
with trifling care in selection of trees. 

7. Deficient soil-depths and denudation of soil about trees pro- 
duce intensely compressed outer rings in the pines of dry areas, and 
this character can be recognized in much prehistoric material. 

136 



SUMMARY 137 



8. Mean sensitivity is a good indicator of climatic correlation, but 
it is strongly affected by injuries to the tree. 

9. Average ring-size, doubling, changing, and other characters of 
rings can be used as indicators in judging the surroundings, and 
especially the climates, of prehistoric and geologic times. 

10. The Prescott correlation between rainfall and tree-growth is 
continued and a similar correlation is found between the Flagstaff 
trees and the winter rainfall recorded there, which, in turn, closely 
resembles California precipitation. A close correlation is also found 
between carefully selected (dry ground) sequoias and San Francisco 
rainfall. 

11. By comparison of smoothed curves, three western centers 
appear; Pike's Peak, Flagstaff, and Sierra Nevada. The Pike's Peak 
area as worked out covers the eastern slope of the mountain; the Flag- 
staff area extends from the Grand Canyon to the Rim and Cibecue, 
175 miles; the Sierra Nevada area extends from the Calaveras Grove 
and even farther north to Mount Wilson and farther south, 500 miles. 
In each of these the curves of growth are homogeneous, and at points 
between these major centers, such as Charleston Mountain or Aztec, 
mixed effects are found. 

12. Dating comparisons of cycles in 200-year curves show 75 per 
cent resemblance in local curves of individual trees, and 50 per cent 
resemblance between Arizona pines and California sequoias, by large 
groups of trees. Practical identity of cycles in yellow-pine groups is 
found across 200 miles between Flagstaff and northwest New Mexico. 

13. The cycles found in the yellow pines of the western zones 
emphasize the approximate simple fractions of 34 or 35 years, with 11 
and 14 years dominating on the coast, 14 and 21 years in Arizona, and 
10 and 11 (or 23) in the Rockies; the coast is deficient in the 20-year 
variations (the separation of 19, 20, and 21 is not yet fully determined 
in these zones); Arizona has less of the 11, 23 year cycles and the 
Rockies are short in the 14, 28 year cycles; they, however, show the 
8.6- and 17.5-year cycles better than the other zones. 

14. A sequoia arcigram (cycle summary over an area) shows a 
little more of the Arizona character in the sequoias than in the yellow 
pines of that region. 

15. The long Flagstaff record, from 1300 to 1925, perhaps the 
best in the three zones for rainfall history, gives cycles which check 
with the known solar record. From them we get a solar period of 
11.30 years lasting for 600 years, but with an interruption from 1630 
to 1850; we get also a group of 7, 14, and 21 year cycles beginning 
near 1660 and well established after 1700. The 21-year cycle has 
dominated Arizona tree-growth for 200 years. A 9.4-year cycle 
shows in the late 1700 's, when the sunspot cycle was of that length. 
The 7-year cycle was less active from 1880 to 1905 (in the Flagstaff 
area mean curve). Growth maxima occur at observed sunspot minima. 

16. Wet and dry climate effects in trees in relation to the solar 
cycle are confirmed. 



138 CLIMATIC CYCLES AND TREE-GROWTH 

17. Provisional results indicate that the 11-year cycle appears in 
the long sequoia records at 1300 to 1100 b. c, 300 b. c, a. d. 35 to 
240; 375 to 475; 600 to 650; 800 to 900 and 1250 onward, with the 
interruption following 1700. 

18. The dry years in the Flagstaff area tree-growth analyze best 
on 14- and 21-year cycles with major droughts at about 150-year 
intervals and minor droughts at 40- or 50-year intervals. 

19. The extension of the cycles observed in the last 200 years in 
the Flagstaff area indicates possible large growth of trees in the 1930 's 
and 1950*8, with depressions in the early and late 1940 's. 

It is recognized that much of this work is new and that time is 
needed to test and improve it, but it is hoped that these preliminary 
results are not greatly in error. 



APPENDIX 



TABLES OF GROUP AVERAGES, STANDARDIZED 

ARIZONA ZONE 

Flagstaff (FL), Appendix, Volume I, Page 113 

Flagstaff University Section (FLU), 500-year trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1700 


0.98 


1.07 


1.00 


0.86 


1.03 


1.22 


1.40 


0.77 


0.69 


0.85 


1710 


1.01 


0.79 


0.85 


0.85 


1.05 


1.08 


1.17 


1.08 


1.20 


1.03 


1720 


1.27 


1.04 


0.93 


1.34 


1.00 


1.22 


1.57 


0.80 


0.94 


0.64 


1730 


1.04 


0.84 


0.95 


0.85 


0.90 


0.51 


0.84 


0.76 


1.14 


0.76 


1740 


0.93 


1.11 


1.11 


1.08 


1.13 


1.11 


1.39 


1.09 


0.64 


1.21 


1750 


0.91 


0.75 


0.45 


0.69 


0.61 


0.72 


0.65 


0.83 


1.15 


0.98 


1760 


1.05 


1.10 


1.37 


1.24 


1.54 


1.23 


0.79 


0.96 


0.82 


0.76 


1770 


0.95 


1.12 


0.88 


0.67 


0.85 


0.97 


0.88 


0.97 


0.60 


0.60 


1780 


0.62 


0.72 


0.51 


1.01 


1.32 


0.62 


0.70 


1.11 


0.95 


0.67 


1790 


0.90 


0.86 


0.99 


1.21 


1.20 


0.92 


0.90 


0.98 


0.79 


0.95 


1800 


0.76 


0.56 


0.97 


0.85 


0.61 


0.77 


0.99 


0.69 


0.86 


0.96 


1810 


0.98 


1.18 


1.09 


0.49 


0.94 


0.86 


0.80 


0.67 


0.60 


0.85 


1820 


0.69 


0.61 


0.53 


0.62 


0.64 


0.92 


1.12 


0.87 


0.96 


0.85 


1830 


0.96 


0.82 


0.98 


1.02 


0.70 


0.80 


0.80 


0.80 


0.76 


0.92 


1840 


1.00 


0.70 


0.72 


0.82 


0.74 


0.67 


0.58 


0.40 


0.80 


0.91 


1850 


1.00 


0.77 


1.13 


1.29 


1.09 


1.02 


1.06 


0.84 


1.11 


0.88 


1860 


0.98 


0.92 


1.07 


0.78 


0.70 


0.86 


1.04 


1.02 


1.33 


1.04 


1870 


1.14 


0.84 


0.94 


0.82 


1.05 


1.06 


0.72 


0.70 


0.85 


0.75 


1880 


0.69 


1.01 


0.88 


0.86 


0.81 


1.10 


0.80 


0.86 


0.95 


0.96 


1890 


1.12 


1.12 


0.98 


1.36 


1.21 


1.05 


1.34 


1.18 


1.26 


0.95 


1900 


0.71 


0.83 


0.80 


0.79 


0.63 


1.14 


1.24 


1.28 


1.64 


1.80 


1910 


1.68 


1.66 


1.42 


1.19 


1.42 


1.36 


1.36 


1.00 


0.95 






Fort Valley (FV), 6 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1680 














0.50 


0.83 


0.85 


0.90 


1690 


6.86 


6.82 


6.90 


1.06 


0.85 


6.76 


0.89 


1.43 


1.30 


1.61 


1700 


1.24 


1.35 


0.97 


1.05 


0.88 


0.70 


1.20 


1.36 


1.28 


1.61 


1710 


1.91 


1.56 


1.54 


1.71 


1.66 


1.54 


1.04 


1.48 


1.59 + 


1.73 


1720 


1.90 


1.33 


1.12 


1.29 


0.95 


1.69 + 


1.65 


0.92 


0.83 


0.43 


1730 


1.04 


0.82 


1.48 


1.44 


1.18 


0.38 


1.11 


0.90 


1.04 


0.81 


1740 


1.33 


1.15 


0.88 


1.54 


1.64 


1.84 


1.98 


1.20 


0.52 


1.26 


1750 


0.77 


0.85 


0.45 


0.79 


0.95 


0.83 


0.84 


0.87 + 


1.28 


1.03 


1760 


1.30 


1.36 


1.33 


0.76 


1.46 


1.07 


1.29 


1.10 


1.01 


10.5 


1770 


1.05 


1.50 


1.48 


0.69 + 


0.83 


1.03 


1.04 


0.81 


0.48 


0.85 


1780 


0.47 


0.60 


0.38 


0.87 


1.28 


1.06 


1.55 


1.93 


1.29 


1.32 


1790 


1.16 


1.12 


1.17 


1.62 


1.43 


1.17 


0.64 


0.95 


0.77 


1.34 


1800 


0.78 


0.81 


1.27 


1.05 


0.98 


0.82 


1.04 


0.93 


0.84 


1.01 


1810 


0.88 


1.01 


0.94 


0.44 


0.51 


0.76 


0.79 


0.65 


0.58 


0.97 


1820 


0.72 


0.71 


0.56 


0.66 


0.81 


1.09 


1.47 + 


1.17 


1.39 


0.75 


1830 


0.92 


1.15 


1.32 


1.37 


1.30 


1.46 


0.83 + 


0.97 + 


1.21 


1.10 


1840 


1.03 


0.54 


0.57 


0.49 


0.81 


0.65 


0.57 


0.36 


0.83 


1.07 


1850 


1.14 


0.58 


1.18 


1.17 


1.24 


1.19 


0.78 


0.74 


1.08- 


0.79 


1860 


0.92 + 


0.96 


1.09 


0.76 


0.66 


0.87- 


1.55 


1.38 


1.90 


1.26 


1870 


1.30 


1.10 


1.26 


1.24 


1.53 


1.17 


0.87 


0.81 


0.91 


0.37 


1880 


0.73 


0.65 


0.76 


0.75 


0.57 


0.80 


0.76 


0.75 


1.06 


1.25 


1890 


1.14 


1.01 


1.07 


1.09 


0.94 


0.67 


0.89 


0.93 


1.14 


0.80 


1900 


1.02 + 


1.43 


1.03 


1.49 + 


1.05 


1.58 


1.62 


1.94 


2.30 


2.19 


1910 


1.49 + 


1.25 


1.39 


1.05 + 


1.30 


1.20 


1.57 


1.54 


0.95 


1.80 


1920 


0.90 









.... 

















139 



140 



CLIMATIC CYCLES AND TREE-GROWTH 



Flagstaff High (FLH), 10 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1630 


. . • • 




.... 


.... 


.... 






4.60 


3.80 


2.90 


1640 


3.60 


4.40 


1.70 


2.50 


3.00 


2.70 


8.50 


3.80 


3.00 


3.50 


1650 


4.30 


4.00 


3.80 


4.20 


3.50 


4.20 


3.90 


2.50 


2.00 


2.30 


1660 


1.20 


0.30 


1.00 


0.90 


0.80 


0.80 


0.80 


0.50 


0.70 


0.50 


1670 


0.50 


0.60 


1.00 


1.00 


1.10 


0.60 


0.90 


1.10 


2.10 


1.50 


1680 


1.80 


1.70 


1.80 


2.50 


3.30 


2.40 


1.90? 


2.90 


2.00 


2.50 


1690 


2.20 


1.50 


2.30 


1.70 


1.60 


1.80 


1.50 


1.30 


1.40 


2.20 


1700 


1.70 


1.60 


1.40 


0.90 


1.60 


2.10 


1.60 


1.40 


1.20 


2.00 


1710 


2.20 


1.20 


1.20 


1.30 


1.40 


1.40 


1.40 


0.90 


1.10 


1.40 


1720 


1.40 


1.30 


1.20 


1.30 


1.20 


1.00 


1.40 


1.60 


1.30 


1.40 


1730 


1.30 


1.30 


1.40 


1.40 


1.10 


0.70 


1.20 


1.00 


1.30 


0.90 


1740 


0.40 


1.00 


2.00 


1.00 


1.00 


1.10 


1.10 


1.00 


0.50 


0.90 


1750 


0.70 


1.10 


0.90 


1.00 


0.80 


0.70 


1.00 


0.90 


0.60 


0.80 


1760 


0.80 


0.80 


0.90 


0.80 


0.70 


0.70 


0.80 


0.80 


0.70 


0.70 


1770 


1.15 


2.10 


2.55 


1.70 


2.15 


2.15 


1.65 


1.90 


2.05 


1.50 


1780 


1.97 


1.93 


1.83 


2.53 


2.37 


2.07 


2.26 


2.63 


1.97 


2.23 


1790 


2.40 


3.08 


2.43 


1.83 


2.08 


1.55 


2.12 


2.33 


2.10 


2.37 


1800 


2.32 


2.21 


2.14 


2.40 


2.31 


2.09 


2.51 


1.99 


2.21 


2.29 


1810 


2.27 


2.04 


2.11 


1.40 


1.87 


1.41 


1.36 


1.44 


1.43 


1.63 


1820 


1.51 


1.36 


1.11 


1.36 


1.57 


1.74 


1.86 


1.27 


1.24 


1.53 


1830 


1.57 


1.40 


1.67 


1.23 


1.84 


1.47 


1.24 


1.68 


1.73 


1.84 


1840 


1.95 


1.40 


1.16 


1.61 


2.08 


1.84 


1.67 


1.61 


1.43 


1.79 


1850 


1.58 


2.03 


2.17 


2.45 


1.80 


2.00 


1.94 


2.49 


2.41 


1.69 


1860 


2.18 


1.79 


1.87 


1.85 


1.71 


1.87 


1.45 


1.72 


1.92 


2.18 


1870 


2.25 


2.01 


1.63 


2.05 


1.58 


2.10 


1.62 


1.81 


1.85 


2.27 


1880 


1.20 


1.60 


1.53 


1.81 


1.49 


1.76 


1.61 


1.80 


1.74 


1.92 


1890 


2.04 


1.72 


1.94 


1.58 


1.80 


1.85 


1.03 


1.31 


1.45 


1.09 


1900 


1.23 


1.18 


1.20 


1.49 


1.55 


1.25 


1.42 


1.74 


1.95 


1.99 


1910 


1.87 


1.62 


1.60 


1.70 


1.75 


1.50 


1.22 


1.33 


1.29 


1.18 


1920 


1.18 


1.06 


1.23 


1.12 


0.52 








.... | 





Flagstaff Shadow (SH), 6 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1710 
















4.80 


6.10 


5.40 


1720 


5.90 


3.60 


4.00 


6.90 


2.60 


3.80 


4.10 


3.30 


3.50 


2.00 


1730 


3.90 


2.20 


2.60 


2.70 


4.50 


1.20 


2.50 


1.30 


0.40 


1.10 


1740 


2.30 


2.10 


2.10 


3.90 


4.30 


4.10 


4.60 


3.70 


1.00 


3.90 


1750 


2.20 


2.30 


0.50 


1.30 


2.90 


2.50 


3.50 


3.00 


3.90 


2.95 


1760 


2.60 


1.85 


2.40 


1.20 


3.05 


2.45 


2.85 


1.95 


2.20 


1.95 


1770 


1.95 


1.65 


1.76 


0.45 


0.80 


1.20 


1.65 


1.00 


0.70 


0.50 


1780 


0.45 


1.05 


1.73 


1.33 


2.00 


0.77 


0.53 


1.80 


0.70 


1.43 


1790 


0.83 


1.53 


2.23 


3.33 


2.23 


2.45 


1.80 


2.08 


1.33 


2.30 


1800 


0.80 


0.83 


1.45 


0.43 


1.03 


0.70 


1.33 


1.23 


1.78 


1.30 


1810 


1.53 


1.70 


1.85 


0.50 


0.55 


0.90 


1.62 


1.15 


0.75 


10.8 


1820 


0.30 


1.40 


0.62 


0.70 


1.60 


1.80 


2.15 


2.38 


2.76 


1.66 


1830 


2.52 


2.45 


2.45 


2.20 


2.18 


2.23 


1.78 


1.55 


2.15 


2.55 


1840 


2.15 


1.30 


1.63 


1.38 


1.98 


1.53 


0.65 


0.75 


1.48 


1.60 


1850 


1.98 


1.45 


2.25 


2.00 


1.80 


1.80 


1.32 


0.58 


0.80 


0.75 


1860 


1.13 


1.35 


1.55 


1.13 


1.08 


1.35 


2.50 


2.75 


3.02 


2.70 


1870 


2.23 


1.50 


1.13 


0.63 


0.87 


0.97 


0.65 


0.60 


0.72 


0.60 


1880 


0.42 


0.60 


0.75 


1.30 


1.52 


1.98 


1.16 


1.12 


1.52 


1.54 


1890 


1.78 


1.76 


1.74 


1.68 


1.60 


1.58 


0.74 


1.10 


1.12 


0.68 


1900 


0.70 


0.68 


0.32 


1.38 


0.94 


1.40 


2.48 


3.02 


2.90 


3.28 


1910 


2.84 


2.40 


2.02 


1.32 


2.08 


2.06 


2.15 


1.38 


2.06 


2.76 


1920 


2.40 


2.02 


2.04 


1.76 


*1.28 






.... 


.... 





* Incomplete. 



APPENDIX 



141 



Flagstaff Northeast (NE), 4 trees 
(Dates prior to 1685 marked "doubtful") 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1670 
















1.10 


1.08 


2.70 


1680 




2.55 


1.33 


1.83 


0.42 


1.05 


i.io 


2.05 


1.90 


1.90 


1690 


1.15 


1.92 


2.24 


2.22 


1.60 


1.60 


0.82 


0.65 


1.68 


1.40 


1700 


0.45 


2.20 


0.87 


0.38 


0.68 


1.05 


0.55 


0.83 


0.42 


0.55 


1710 


1.20 


1.15 


1.50 


1.65 


1.75 


1.95 


2.30 


2.50 


3.48 


4.70 


1720 


4.45 


2.40 


0.95 


1.78 


1.46 


2.37 


4.23 


2.76 


2.29 


1.14 


1730 


1.13 


1.38 


1.49 


0.56 


1.37 


0.39 


1.26 


0.74 


1.36 


1.02 


1740 


1.70 


1.89 


1.08 


2.31 


2.09 


2.72 


3.83 


3.35 


1.10 


2.11 


1750 


1.47 


1.53 


0.83 


1.49 


1.82 


0.68 


1.80 


2.03 


3.02 


3.53 


1760 


3.42 


1.77 


2.31 


1.18 


1.40 


1.85 


1.98 


1.66 


1.79 


1.39 


1770 


1.21 


1.51 


0.90 


0.64 


0.79 


0.93 


1.41 


1.34 


0.75 


0.91 


1780 


0.79 


0.73 


0.89 


1.75 


1.33 


0.54 


0.62 


1.27 


0.85 


0.77 


1790 


1.00 


1.24 


1.56 


2.12 


1.84 


1.67 


1.83 


1.41 


0.80 


1.08 


1800 


0.63 


0.41 


0.47 


0.45 


1.08 


0.46 


1.02 


0.89 


1.12 


1.14 


1810 


1.22 


1.55 


1.37 


0.60 


1.44 


1.81 


1.67 


1.67 


1.43 


1.36 


1820 


0.87 


1.15 


0.91 


1.31 


1.54 


1.53 


1.98 


1.63 


2.01 


1.21 


1830 


1.64 


1.61 


1.59 


1.64 


0.89 


1.38 


1.18 


1.02 


1.59 


1.71 


1840 


1.88 


1.46 


0.68 


1.14 


1.55 


0.31 


0.61 


0.12 


0.85 


0.87 


1850 


1.06 


0.77 


1.09 


1.07 


0.71 


0.90 


0.74 


0.09 


0.77 


0.40 


1860 


0.63 


0.60 


0.58 


0.49 


0.26 


0.57 


0.65 


0.83 


1.20 


1.19 


1870 


0.77 


0.40 


0.43 


0.57 


0.62 


0.80 


0.61 


0.26 


0.35 


0.25 


1880 


0.33 


0.10 


0.35 


0.29 


0.43 


0.77 


0.63 


0.68 


0.71 


0.72 


1890 


0.97 


0.85 


1.12 


0.85 


1.07 


0.95 


0.59 


0.84 


0.70 


0.35 


1900 


0.50 


0.41 


0.13 


0.48 


0.13 


0.66 


0.83 


1.32 


1.38 


1.62 


1910 


1.51 


1.74 


1.35 


0.94 


1.24 


1.11 


1.12 


1.20 


1.22 


1.29 


1920 


1.38 


1.25 


1.27 

















Grand Canyon (GC), 7 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


, 


1710 














1.25 


1.55 


2.95 


1.20 


1720 


2.66 


2.15 


6.60 


1.90 


6.60 


6.90 


1.50 


1.25 


0.95 


0.50 


1730 


0.80 


1.15 


2.00 


1.10 


0.60 


0.30 


0.60 


0.45 


1.10 


0.40 


1740 


1.25 


1.30 


0.90 


1.30 


1.05 


1.20 


2.05 


2.12 


0.67 


1.90 


1750 


1.25 


0.92 


0.35 


0.47 


0.48 


0.47 


0.67 


0.82 


1.27 


0.95 


1760 


1.15 


0.92 


1.28 


0.93 


1.83 


1.03 


1.13 


1.35 


1.60 


0.93 


1770 


0.77 


1.50 


1.27 


0.58 


0.80 


0.90 


1.30 


0.95 


0.38 


0.92 


1780 


1.23 


0.93 


0.50 


0.98 


1.50 


0.53 


0.95 


1.42 


0.78 


0.93 


1790 


0.80 


1.13 


0.95 


2.00 


0.76 


1.22 


0.84 


0.70 


0.53 


1.09 


1800 


0.45 


0.45 


0.81 


0.44 


0.71 


0.62 


0.44 


0.78 


0.81 


0.64 


1810 


0.30 


0.74 


0.96 


0.24 


0.52 


0.50 


0.73 


0.65 


0.31 


0.52 


1820 


0.28 


0.61 


0.25 


0.39 


0.52 


0.86 


0.89 


0.87 


1.03 


0.36 


1830 


0.49 


0.74 


0.68 


0.85 


0.60 


0.87 


0.54 


0.86 


0.81 


1.11 


1840 


1.16 


0.69 


0.42 


0.44 


0.75 


0.13 


0.23 


0.07 


0.55 


0.83 


1850 


0.89 


0.61 


0.74 


0.74 


0.87 


0.96 


0.79 + 


0.66 


0.84 


0.49 


1860 


0.51 


0.44 


0.83 


0.52 


0.31 


0.63 


1.18 


0.85 


1.66 


1.33 


1870 


0.80 


0.66- 


0.61 


0.45 


0.90 


0.88 


0.55 


0.48 


0.79 


0.27 


1880 


0.28 


0.25 


0.30 


0.35 


0.69 + 


1.08 


0.97 


0.50 


1.16 + 


1.18 


1890 


1.68 


1.66 + 


1.66 


1.41 


0.84 


1.17 


0.32 + 


0.86 


0.79 + 


0.16 + 


1900 


0.28 + 


0.35 


0.37 


0.67 


0.06 


0.61 


1.01 


1.32 


1.23 


2.17 


1910 


1.08 


1.39 + 


1.07 


0.67 


1.19 


1.07 


1.14 


0.82 


0.39 + 


0.89 



142 



CLIMATIC CYCLES AND TREE-GROWTH 



Dixie Forest (DF), 10 trees 



A.D. 





1 


2 


3 


4 


S 


6 


7 


8 


9 
1.26 


1610 


• • • • 


• • • • 


• . • • 


• • 






1.56 


1.62 


2.20 


1620 


1.26 


2.26 


1.06 


1.76 


i.oo 


i.Yo 


1.95 


1.85 


2.20 


2.40 


1630 


1.85 


1.50 


1.40 


2.50 


2.30 


2.35 


2.60 


1.65 


2.15 


1.40 


1640 


2.20 


1.75 


2.25 


2.30 


2.50 


2.20 


1.65 


2.35 


1.85 


2.10 


1650 


2.30 


3.10 


3.75 


1.35 


2.60 


1.50 


2.05 


2.20 


2.45 


2.25 


1660 


2.28 


2.70 


2.70 


2.05 


2.45 


1.80 


1.85 


2.40 


1.80 


1.95 


1670 


1.30 


2.40 


2.45 


2.10 


2.35 


1.65 


1.50 


2.10 


1.75 


1.75 


1680 


2.10 


2.15 


1.50 


2.90 


1.60 


2.50 


1.40 


2.10 


1.65 


1.75 


1690 


1.15 


1.65 


1.80 


1.65 


2.10 


2.15 


1.75 


1.55 


1.65 


1.95 


1700 


2.10 


1.95 


1.85 


1.30 


1.65 


2.10 


2.15 


0.70 


0.55 


0.95 


1710 


1.30 


1.55 


0.95 


0.85 


1.10 


1.05 


1.42 


1.35 


1.52 


1.70 


1720 


2.10 


1.85 


1.87 


1.80 


2.37 


1.77 


2.31 


1.74 


1.79 


1.02 


1730 


1.56 


1.71 


1.21 


1.50 


1.44 


0.35 


1.32 


1.09 


1.35 


1.24 


1740 


1.52 


1.56 


1.14 


1.40 


1.45 


1.51 


1.76 


1.76 


1.35 


1.94 


1750 


1.26 


1.46 


0.89 


1.21 


1.19 


1.24 


1.02 


1.41 


1.15 


1.11 


1760 


1.24 


1.15 


1.09 


0.77 


0.89 


1.13 


1.34 


1.27 


1.11 


1.27 


1770 


1.36 


1.30 


1.16 


1.40 


1.46 


1.46 


1.40 


1.17 


1.39 


1.33 


1780 


1.38 


1.21 


1.01 


1.22 


1.78 


1.12 


1.14 


1.50 


1.13 


1.68 


1790 


1.46 


1.45 


1.62 


1.36 


1.56 


1.17 


1.26 


1.36 


1.18 


1.42 


1800 


1.24 


1.44 


1.60 


1.06 


1.24 


1.43 


1.27 


1.24 


1.28 


1.47 


1810 


1.32 


1.52 


1.27 


1.16 


1.34 


1.24 


1.30 


1.28 


1.27 


1.30 


1820 


0.96 


1.30 


0.94 


0.92 


0.97 


1.26 


1.20 


1.22 


1.53 


1.40 


1830 


1.23 


1.48 


1.70 


1.60 


1.16 


1.22 


1.01 


1.20 


0.98 


1.18 


1840 


1.33 


0.98 


0.90 


1.04 


1.18 


1.03 


1.17 


0.94 


1.03 


1.53 


1850 


1.34 


1.04 


1.12 


1.30 


1.26 


1.35 


1.14 


1.26 


1.22 


1.18 


1860 


1.15 


1.02 


1.34 


1.37 


0.91 


1.02 


1.43 


1.41 


1.45 


1.40 


1870 


1.61 


1.22 


1.20 


1.10 


1.38 


1.34 


1.00 


1.30 


1.14 


0.68 


1880 


0.85 


0.97 


1.17 


1.18 


1.19 


1.58 


1.14 


1.44 


1.42 


1.16 


1890 


1.30 


1.45 


1.43 


1.37 


1.52 


1.40 


1.34 


1.43 


1.50 


1.34 


1900 


1.30 


1.57 


1.34 


1.38 


1.59 


1.46 


1.59 


1.79 


1.78 


1.66 


1910 


1.79 


1.64 


1.60 


1.55 


1.63 


1.61 


1.67 


1.39 


1.34 


1.44 


1920 


1.17 


1.21 


1.35 


1.00 

























Rim High (RH) 


2 trees 










A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1690 
















0.98 


1.22 


1.58 


1700 


1.20 


1.26 


1.05 


1.22 


0.75 


0.98 


i!o4 


0.55 


0.79 


1.31 


1710 


1.42 


0.66 


0.92 


1.19 


1.12 


1.17 


0.97 


0.96 


1.22 


0.98 


1720 


1.26 


0.92 


0.60 


1.13 


0.90 


0.82 


1.09 


0.53 


0.70 


0.55 


1730 


0.69 


0.60 


0.78 


0.47 


1.00 


0.37 


0.84 


0.74 


0.66 


0.53 


1740 


1.03 


0.63 


0.72 


0.80 


0.56 


0.86 


1.12 


0.93 


0.25 


0.79 


1750 


0.91 


0.66 


0.40 


0.65 


0.92 


1.04 


0.86 


0.75 


0.86 


1.15 


1760 


1.22 


0.70 


0.90 


0.90 


1.55 


1.30 


1.50 


1.80 


1.20 


1.00 


1770 


1.45 


1.40 


0.80 


0.90 


0.85 


0.60 


1.00 


0.85 


1.06 


0.83 


1780 


1.00 


1.10 


0.63 


0.82 


1.69 


0.80 


1.20 


1.40 


1.08 


0.79 


1790 


0.71 


0.79 


0.88 


1.20 


1.01 


0.88 


0.70 


0.65 


0.53 


0.70 


1800 


0.65 


0.60 


0.98 


0.93 


1.00 


1.18 


0.75 


0.96 


1.00 


0.92 


1810 


0.81 


1.12 


0.87 


0.68 


0.65 


0.90 


0.83 


0.55 


0.69 


0.51 


1820 


0.56 


0.55 


0.51 


0.41 


0.45 


0.57 


0.63 


0.48 


0.48 


0.35 


1830 


0.52 


0.46 


0.48 


0.45 


0.65 


0.58 


0.70 


0.70 


0.80 


0.73 


1840 


0.72 


0.44 


0.57 


0.68 


0.71 


0.29 


0.70 


0.42 


0.68 


0.80 


1850 


0.70 


0.70 


0.91 


0.63 


0.70 


0.55 


0.78 


0.61 


0.76 


0.72 


1860 


0.72 


0.80 


0.65 


0.66 


0.68 


0.82 


1.20 


0.76 


1.10 


0.48 


1870 


0.78 


0.76 


0.73 


0.43 


0.83 


0.83 


0.72 


0.81 


0.98 


0.65 


1880 


0.78 


0.80 


0.66 


0.80 


0.82 


0.72 


0.52 


0.80 


0.82 


0.70 


1890 


0.85 


0.63 


0.59 


1.02 


0.50 


0.62 


0.88 


0.79 


0.78 


0.78 


1900 


0.50 


0.75 


0.48 


0.76 


0.25 


0.75 


0.76 


0.84 


1.06 


0.90 


1910 


0.70 


0.80 


0.75 


0.58 


0.80 


0.68 


0.62 


0.82 


0.52 


0.66 


1920 


0.59 


0.76 


0.55 










.... 











APPENDIX 



143 











Rim Low (RL) , 


2 trees 










A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1770 


1.00 


1.43 


1.43 


0.98 


1.02 


1.10 


1.35 


1.27 


0.84 


0.71 


1780 


0.68 


0.75 


0.51 


0.77 


1.49 


0.92 


0.95 


1.35 


0.97 


0.99 


1790 


0.93 


1.27 


1.14 


1.69 


1.00 


0.84 


0.70 


0.95 


0.65 


0.87 


1800 


0.72 


0.71 


0.84 


0.50 


0.79 


0.68 


0.83 


1.00 


1.05 


0.95 


1810 


0.49 


1.18 


1.16 


0.56 


0.94 


1.13 


0.65 


0.85 


0.77 


0.41 


1820 


0.12 


0.70 


0.36 


0.28 


0.85 


0.75 


1.13 


1.43 


1.50 


1.53 


1830 


1.29 


0.61 


1.50 


1.22 


0.86 


1.06 


1.08 


0.82 


0.71 


1.52 


1840 


1.46 


0.78 


0.78 


0.84 


0.89 


0.62 


0.63 


0.27 


0.83 


0.75 


1850 


0.60 


0.78 


1.32 


0.85 


0.73 


0.96 


0.55 


0.28 


0.77 


0.38 


1860 


0.58 


0.44 


0.62 


0.39 


0.24 


0.70 


0.60 


0.90 


1.41 


1.44 


1870 


0.95 


0.74 


0.66 


0.48 


0.39 


0.86 


0.70 


0.68 


0.93 


0.32 


1880 


0.58 


0.41 


0.35 


0.45 


0.92 


1.38 


0.92 


0.78 


1.36 


1.08 


1890 


1.25 


1.42 


0.90 


1.26 


0.39 


1.19 


0.44 


0.84 


0.84 


0.60 


1900 


0.36 


0.79 


0.06 


0.42 


0.08 


0.95 


0.98 


1.31 


1.85 


1.49 


1910 


1.31 


1.41 


1.32 


0.63 


1.45 


1.01 


1.12 


1.28 


1.05 


1.22 


1920 


1.33 


1.02 














.... 





Cibecue (J), 5 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1650 






1.02 


1.43 


1.10 


0.75 


1.13 


0.86 


0.43 


0.66 


1660 


0.80 


1.09 


1.12 


1.40 


1.33 


1.37 


1.11 


1.00 


0.75 


0.63 


1670 


0.21 


1.02 


0.77 


1.00 


0.88 


0.80 


0.90 


0.87 


0.67 


0.95 


1680 


1.30 


1.43 


0.92 


1.43 


0.27 


0.13 


1.20 


1.40 


1.60 


1.55 


1690 


1.66 


1.20 


1.60 


1.05 


1.80 


1.70 


1.00 


1.70 


0.93 


2.83 


1700 


1.03 


0.98 


1.24 


0.87 


1.13 


1.35 


1.34 


0.35 


0.55 


0.72 


1710 


1.24 


0.68 


0.71 


0.69 


1.35 


0.62 


0.40 


0.90 


1.17 


0.96 


1720 


1.10 


1.02 


0.66 


1.03 


0.44 


0.95 


1.15 


0.90 


0.75 


0.33 


1730 


0.73 


0.41 


0.90 


0.48 


0.85 


0.18 


0.72 


0.83 


1.10 


0.53 


1740 


1.28 


1.16 


0.73 


1.00 


0.82 


1.11 


1.35 


1.62 


0.80 


1.96 


1750 


1.33 


0.58 


0.18 


0.40 


0.65 


0.45 


0.48 


0.38 


0.68 


0.72 


1760 


0.66 


0.60 


1.18 


0.40 


1.59 


0.81 


1.38 


0.92 


1.16 


0.93 


1770 


0.99 


1.22 


0.96 


0.29 


0.86 


0.82 


0.81 


0.62 


0.39 


0.58 


1780 


0.27 


0.36 


0.12 


0.59 


1.08 


0.43 


0.69 


1.10 


0.67 


0.59 


1790 


0.52 


0.82 


1.08 


1.77 


0.86 


1.06 


0.89 


0.43 


0.52 


0.61 


1800 


0.38 


0.27 


0.43 


0.12 


0.47 


0.29 


0.36 


0.44 


0.51 


0.47 


1810 


0.29 


0.50 


0.47 


0.39 


0.41 


0.53 


0.68 


0.58 


0.40 


0.12 


1820 


0.04 


0.34 


0.03 


0.28 


0.28 


0.48 


0.33 


0.13 


0.72 


0.44 


1830 


0.38 


0.42 


0.43 


0.68 


0.62 


0.50 


0.52 


0.44 


0.62 


0.91 


1840 


0.68 


0.42 


0.40 


0.33 


0.70 


0.20 


0.20 


0.12 


0.15 


0.46 


1850 


0.55 


0.45 


0.82 


0.73 


0.43 


0.47 


0.88 


0.57 


0.88 


0.55 


1860 


0.90 


0.49 


1.03 


0.77 


0.26 


0.92 


0.91 


1.01 


1.28 


1.23 


1870 


0.84 


0.38 


0.83 


0.38 


0.47 


0.78 


0.57 


0.49 


0.44 


0.60 


1880 


0.43 


0.41 


0.42 


0.49 


0.57 


0.66 + 


0.64 


0.46 


0.57 


0.59 


1890 


0.90 


0.82 


0.78 


0.41 


0.20 


0.34 


0.44 


0.40 


0.40 


0.37 


1900 


0.12 


0.35 


0.10 


0.21 


0.12 


0.47 


0.71 


0.76 


0.91 


1.01 


1910 


0.76 


1.04 


0.65 


0.42 


1.03 


0.84 


0.96 


1.17 


0.90 


0.88 


1920 


0.67 
















.... 






144 



CLIMATIC CYCLES AND TREE-GROWTH 











Pined (PNL), 


S trees 










A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1760 


0.73 


1.10 


1.35 


0.72 


1.30 


0.92 


0.65 


0.60 


0.90 


0.80 


1770 


0.80 


1.15 


0.80 


0.45 


0.55 


0.70 


0.42 


0.50 


0.65 


0.60 


1780 


0.63 


0.55 


0.35 


0.58 


0.68 


0.63 


0.78 


1.05 


0.55 


0.92 


1790 


0.75 


0.58 


0.73 


0.60 


0.68 


0.55 


0.68 


0.65 


0.75 


0.98 


1800 


0.95 


0.75 


0.95 


0.85 


0.78 


0.96 


0.69 


0.64 


0.86 


0.93 


1810 


0.67 


0.46 


0.50 


0.42 


0.59 


0.56 


0.47 


0.62 


0.44 


0.38 


1820 


0.27 


0.69 


0.36 


0.33 


1.08 


1.11 


0.98 


1.00 


1.23 


0.88 


1830 


1.36 


0.92 


1.37 


1.37 


0.83 


0.90 


0.87 


0.69 


0.90 


1.14 


1840 


0.89 


0.47 


0.84 


1.09 


1.36 


0.84 


0.90 


0.44 


1.15 


1.00 


1850 


1.35 


1.52 


2.17 


1.11 


0.94 


0.84 


0.86 


0.79 


1.07 


0.73 


1860 


0.91 


0.75 


0.94 


0.42 


0.33 


0.80 


1.15 


0.55 


0.95 


0.99 


1870 


0.57 


0.43 


0.56 


0.44 


0.49 


0.88 


1.03 


0.78 


0.95 


0.90 


1880 


0.48 


0.95 


0.80 


0.60 


0.85 


0.87 


0.50 


0.64 


0.48 


0.41 


1890 


0.87 


0.79 


0.36 


0.51 


0.47 


0.46 


0.57 


1.07 


0.83 


1.01 


1900 


0.015 


0.36 


0.73 


0.56 


0.42 


1.09 


1.28 


1.22 


2.14 


2.13 


1910 


0.66 


0.68 


0.64 


0.40 


0.54 


0.68 


0.53 


0.41 


0.27 


0.32 


1920 


0.36 


0.47 


0.43 


0.23 















Santa Catalina (SO, 8 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1560 
















1.02 


1.46 


1.85 


1570 


1.47 


1.67 


6.87 


1.20 


6.98 


1.42 


1.42 


1.27 


1.03 


0.88 


1580 


1.08 


1.63 


1.46 


1.10 


1.11 


1.60 


1.50 


1.20 


1.20 


1.30 


1590 


0.68 


0.95 


1.17 


1.16 


1.04 


1.10 


1.11 


1.40 


1.22 


1.14 


1600 


1.75 


1.44 


1.51 


1.20 


0.93 


1.38 


0.91 


1.45 


1.29 


1.24 


1610 


1.60 


1.10 


0.80 


1.23 


1.21 


0.87 


1.39 


1.19 


0.98 


1.43 


1620 


1.31 


0.85 


0.91 


0.81 


0.68 


0.47 


0.19 


0.26 


0.30 


0.39 


1630 


0.65 


0.78 


1.30 


2.02 


1.73 


1.10 


1.56 


1.16 


1.03 


1.35 


1640 


1.21 


0.90 


0.96 


0.72 


0.68 


0.83 


1.07 


1.65 


1.53 


1.00 


1650 


1.81 


0.67 


0.72 


0.89 


1.00 


1.40 


1.00 


0.59 


0.65 


0.61 


1660 


0.34 


0.65 


0.41 


0.51 


0.55 


0.80 


1.34 


1.04 


2.02 


1.86 


1670 


1.80 


1.74 


1.48 


1.49 


1.19 


1.52 


1.54 


1.25 


1.71 


0.94 


1680 


0.71 


1.51 


1.05 


1.10 


1.15 


0.87 


1.17 


1.22 


1.44 


0.96 


1690 


1.48 


1.13 


1.15 


1.06 


0.74 


0.48 


0.78 


1.06 


0.43 


1.08 


1700 


0.89 


0.80 


1.07 


1.12 


1.09 


0.81 


0.79 


0.85 


0.99 


0.96 


1710 


0.82 


0.58 


0.70 


0.85 


0.65 


0.59 


0.48 


0.59 


0.68 


0.85 


1720 


0.66 


0.84 


0.78 


0.79 


0.84 


0.81 


0.83 


0.91 


0.83 


1.46 


1730 


1.36 


1.51 


1.51 + 


1.39 


1.11 


1.00 


1.06 


1.20 


1.17 


0.88 


1740 


0.81 


1.21 


0.95 


1.08 


0.77 


0.77 


0.80 


0.76 


0.41 


0.73 


1750 


0.74- 


0.68 + 


0.51 


0.56 


0.80 


0.91 


0.82 


0.98 


0.96 


1.01 


1760 


0.86 


1.06 


0.98 


1.03 


1.18 


1.16 


1.12 


1.10 


1.01 


0.96 


1770 


1.09 


1.02 


1.04 


0.98 


1.07 


1.14 


1.14 


1.19 


1.38 


1.09 


1780 


1.17 


1.32 


1.01 


1.19 


1.18 


1.13 


0.79 + 


0.78- 


0.75 


0.65 


1790 


0.72 


0.97 


1.29 


1.29 


1.39 


1.13 


0.87 


0.95 


0.83 


0.99 


1800 


1.20 


1.11 


0.95 


0.99 + 


1.09 


1.21 


1.41 


1.21 


1.04 


1.37 


1810 


1.29 


1.21 


1.04 


1.10 


1.32 


1.33 


1.32 


1.03 


0.80 


0.73 


1820 


0.85 


0.74 


0.65 


0.83 


0.84 


0.91 


1.08 


1.01 


0.90 


1.12 


1830 


1.28 


0.82 


1.24 


0.82 


0.56 


0.94 


0.67 


0.82 


0.93 


1.08 


1840 


1.14 


0.94 


0.94 


1.34 


1.59 


1.80 


1.20 


1.42 


1.38 


1.08 


1850 


1.19 


0.72 


0.96 


1.16 


0.82 


0.51 


0.78 


0.97 


0.95- 


0.69- 


1860 


1.13 


1.07 


0.74 


0.89 


0.70 


0.50 


0.83 


0.51 


0.54 


0.53 


1870 


0.64 


0.74 


0.89 


0.79 


0.77 + 


0.97 


0.89 


0.80 


1.13 


1.35 


1880 


0.94 + 


0.88 


1.02 


0.91 


1.10 


1.18 


0.88 


0.82 


1.01 


0.98 


1890 


0.95 


0.68 


0.74 


0.96 


0.81 


0.80 


0.88 


0.70 


1.09 


0.89 


1900 


0.78 


0.89 


0.76 


0.76 


0.74 


0.96 


0.53 


0.74 + 


0.95 


0.68 


1910 


0.46 


0.57 


0.58 


0.62 


0.83 


0.45 


0.65 


0.79 


0.52 


0.75 


1920 


0.79 + 





















APPENDIX 



145 



Santa Rita (SR), 5 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1670 


0.82 


0.52 


0.47 


0.64 


0.74 


1.00 


2.18 


1.20 


1.87 


1.00 


1680 


1.07 


1.20 


1.09 


0.95 


1.14 


1.11 


1.13 


1.41 


1.43 


0.85 


1690 


0.59 


0.77 


0.98 


1.12 


1.38 


0.80 


0.72 


1.05 


1.18 


1.27 


1700 


1.00 


1.20 


1.00 


1.58 


1.30 


1.04 


0.91 


0.85 


1.12 


1.14 


1710 


1.30 


0.72 


0.72 


0.44 


1.04 


0.84 


0.85 


1.12 


1.25 


1.22 


1720 


1.31 


1.06 


1.06 


1.10 


1.40 


1.18 


1.51 


0.61 


1.20 


1.02 


1730 


0.97 


1.61 


1.68 


0.86 


0.87 


0.56 


1.18 


0.88 


0.87 


0.58 


1740 


0.86 


0.78 


1.03 


1.93 


1.74 


1.21 


1.42 


1.70 


0.62 


0.46 


1750 


0.78 


0.12 


0.69 


0.40 


0.42 


0.66 


0.78 


1.00 


1.10 


0.76 


1760 


1.08 


1.22 


0.66 


1.11 


1.01 


0.79 


1.04 


1.04 


1.13 


0.98 


1770 


0.98 


0.67 


0.90 


0.53 


0.50 


0.55 


0.60 


0.75 


0.59 


0.70 


1780 


0.80 


0.67 


1.02 


0.90 


1.10 


0.70 


0.62 


0.81 


1.01 


0.99 


1790 


0.69 


0.66 


0.85 


0.83 


0.57 


0.66 


0.78 


0.39 


0.39 


1.08 


1800 


0.56 


0.23 


0.77 


1.03 


1.18 


1.28 


1.11 


1.22 


0.87 


1.30 


1810 


1.58 


1.31 


1.54 


1.06 


1.51 


1.49 


1.47 


0.97 


1.22 


0.41 


1820 


0.61 


0.62 


0.68 


0.82 


0.95 


0.89 


1.50 


1.42 


1.45 


1.32 


1830 


1.35 


1.14 


1.30 


1.05 


0.78 


0.97 


0.83 


0.95 


0.96 


1.41 


1840 


1.53 


0.84 


0.62 


1.12 


1.55 


1.32 


1.05 


0.39 


0.58 


0.78 


1850 


0.95 + 


0.87 


1.03 


1.32 


1.26 


1.33 


1.29 


0.97 


1.00 


1.12 


1860 


1.23 


1.17 


0.86 


0.81 


0.72 


0.85 


0.79 


0.68 


0.94 


0.98 


1870 


0.80 


0.77 


0.65 


0.78 


0.64 


0.77 


0.44 


0.88 + 


0.80 


0.75 


1880 


0.53 


1.02 


1.22 


1.19 


1.04 


1.05 


0.46 


0.54 


0.92 


0.76 


1890 


0.75 


0.66 


0.39 + 


0.37 


0.53 


0.43 


0.97 


0.90 


1.22 


1.21 


1900 


0.77 


0.91 


0.63 


1.13 


0.71 


1.24 


1.09 


1.25 


1.39 


1.13 


1910 


0.84 


1.30 


0.71 


0.96 


1.30 


0.92 


1.06 


1.15 


0.91 


1.19 


1920 


0.84 


0.62 



















ROCKY MOUNTAIN ZONE 
Yellowstone (F), 5 trees 



A.D. 





1 


2 


3 


4 


5 


6 


!7 


8 


9 


1690 








1.00 


1.16 


1.16 


0.88 


0.66 


1.02 


0.77 


1700 


0.74 


1.09 


i.oo 


1.12 


0.98 


1.06 


0.95 


0.79 


1.00 


1.29 


1710 


1.00 


0.95 


1.22 


1.16 


1.16 


1.09 


1.12 


0.81 


0.83 


0.87 


1720 


0.89 


0.87 


0.80 


1.06 


0.97 


1.00 


0.95 


1.06 


1.26 


1.23 


1730 


1.02 


0.85 


1.03 


1.21 


1.24 


0.95 


0.93 


1.46 


1.08 


1.11 


1740 


1.00 


1.15 


1.03 


0.85 


0.75 


1.05 


1.13 


1.17 


1.20 


1.18 


1750 


1.04 


1.05 


1.13 


1.13 


0.91 


0.95 


1.06 


1.05 


1.11 


1.50 


1760 


1.36 


0.98 


0.98 


1.11 


1.01 


1.11 


1.01 


1.25 


1.37 


1.35 


1770 


1.10 


1.04 


1.16 


1.21 


1.36 


1.00 


1.43 


1.29 


1.28 


1.17 


1780 


1.43 


1.00 


0.87 


0.86 


0.97 


0.78 


0.94 


1.16 


1.03 


1.29 


1790 


1.03 


1.33 


1.27 


1.35 


1.17 


1.38 


1.16 


0.90 


0.98 


0.84 


1800 


1.00 


0.94 


1.00 


0.91 


1.10 


0.93 


0.89 


0.75 


1.03 


0.79 


1810 


0.92 


0.88 


0.93 


1.12 


0.91 


1.26 


1.24 


1.48 


1.36 


1.27 


1820 


1.40 


1.12 


1.04 


0.96 


1.02 


0.96 


1.15 


1.33 


1.11 


1.13 


1830 


1.06 


1.13 


0.97 


0.97 


1.22 


1.14 


1.14 


1.18 


1.08 


1.19 


1840 


1.04 


1.35 


1.47 


1.78 


1.55 


1.10 


1.32 


1.02 


0.94 


1.04 


1850 


1.00 


1.09 


0.83 


1.09 


1.08 


0.82 


0.92 


1.12 


0.94 


1.01 


1860 


1.13 


1.37 


1.01 


1.10 


0.87 


0.83 


1.04 


1.00 


1.15 


0.98 


1870 


0.88 


0.84 


0.89 


0.86 


0.97 


0.94 


0.95 


1.11 


1.17 


1.38 


1880 


1.12 


1.17 


1.20 


0.75 


1.05 


1.09 


1.09 


1.12 


1.26 


1.15 


1890 


1.18 


1.19 


1.14 


1.11 


1.15 


1.12 


0.92 


1.17 


0.95 


0.74 


1900 


1.03 


0.96 


0.74 


0.83 


0.83 


0.98 


0.77 


0.90 


1.02 


0.98 


1910 


1.16 


1.06 


0.99 


1.09 


1.08 


0.89 


0.84 


0.79 


0.88 


0.87 


1920 


0.87 





















146 



CLIMATIC CYCLES AND TREE-GROWTH 



Laramie, Wyoming (LW) , 3 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1750 










1.95 


1.20 


0.55 


0.35 


0.65 


0.80 


1760 


6.80 


1.75 


0.95 


1.15 


0.95 


1.10 


1.20 


1.35 


1.70 


1.80 


1770 


0.90 


1.35 


1.00 


0.80 


1.05 


1.20 


1.20 


0.50 


1.50 


1.50 


1780 


1.60 


1.90 


1.00 


1.30 


2.15 


1.95 


1.10 


2.05 


0.85 


0.50 


1790 


1.40 


1.30 


1.15 


1.70 


2.00 


1.25 


1.20 


0.30 


0.45 


1.60 


1800 


1.60 


1.30 


2.40 


2.55 


0.70 


0.45 


0.95 


0.50 


1.05 


0.85 


1810 


1.30 


1.25 


1.05 


1.05 


1.10 


1.00 


1.05 


1.20 


1.00 


1.25 


1820 


0.55 


1.20 


1.65 


1.25 


0.60 


1.40 


1.10 


1.05 


1.85 


1.32 


1830 


0.96 


0.90 


0.94 


1.12 


1.16 


1.37 


1.58 


1.78 


1.69 


1.84 


1840 


1.52 


1.46 


0.53 


1.89 


1.48 


0.86 


1.04 


0.61 


0.57 


0.98 


1850 


1.05 


0.72 


1.14 


1.56 


1.09 


0.59 


0.59 


0.59 


1.16 


1.31 


1860 


1.51 


0.43 


1.63 


0.56 


1.05 


0.92 


1.54 


1.53 


1.68 


1.86 


1870 


1.63 


0.91 


1.75 


1.31 


0.66 


1.56 


1.36 


0.65 


1.63 


0.92 


1880 


0.26 


0.18 


0.99 


0.78 


0.81 


0.98 


0.82 


0.78 


1.19 


1.32 


1890 


1.03 


1.83 


1.24 


0.93 


0.93 


1.21 


1.08 


1.46 


1.42 


1.21 


1900 


0.92 


1.39 


1.18 


1.66 


1.65 


1.46 


2.14 


1.99 


1.84 


1.72 


1910 


1.43 


1.18 


1.31 


1.74 


1.46 


1.93 


1.00 


1.55 


1.48 


0.58 


1920 


1.47 


1.60 


1.15 


1.62 


1.41 










.... 



Clements' Pike's Peak (O, 8 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1770 




.... 


.... 












1.41 


1.86 


1780 


1.78 


2.38 


2.16 


1.26 


1.62 


1.41 


1.79 


1.75 


2.00 


1.41 


1790 


2.27 


2.20 


2.56 


2.52 


2.42 


2.36 


2.46 


1.91 


1.83 


1.23 


1800 


1.73 


1.14 


1.65 


2.13 


1.60 


1.12 


1.77 


1.77 


1.32 


1.53 


1810 


1.60 


1.55 


1.92 


1.65 


1.31 


1.71 


1.95 


1.68 


1.53 


1.71 


1820 


1.54 


1.31 


1.19 


1.33 


0.913 


1.19 


1.45 


1.48 


1.80 


1.45 


1830 


1.34 


1.68 


1.08 


1.41 


1.49 


1.72 


1.83 


1.95 


2.31 


2.08 


1840 


2.15 


1.51 


1.32 


1.58 


1.65 


1.44 


1.39 


1.27 


1.41 


1.48 


1850 


1.25 


0.567 


1.49 


1.47 


1.76 


1.17 


0.92 


1.35 


1.81 


1.07 


1860 


1.32 


0.523 


1.00 


0.603 


1.10 


0.81 


1.23 


1.36 


1.13 


1.68 


1870 


1.08 


0.863 


1.09 


1.08 


1.06 


1.22 


1.18 


1.08 


1.37 


0.937 


1880 


0.357 


0.891 


0.801 


0.885 


0.672 


0.782 


0.702 


0.693 


0.654 


0.794 


1890 


0.57 


0.705 


0.734 


0.439 


0.581 


0.720 


0.594 


0.796 


0.970 


0.351 


1900 


0.808 


0.729 


0.823 


0.952 


1.31 


1.12 


1.01 


0.979 


0.623 


0.953 


1910 


0.917 


0.668 


0.842 


0.95 


1.08 


1.18 


0.994 


0.734 


0.67 


0.81 









Pike 


s Peak, 11,600 Feet (PPT), 


5 trees 








A.D. 





1 


2 


3 


4 


S 


6 


7 


8 


9 


1730 










0.81 


0.78 


0.70 


0.79 


0.82 


0.91 


1740 


6.98 


1.12 


1.16 


i.66 


1.18 


1.00 


1.09 


1.20 


0.82 


1.15 


1750 


1.18 


1.06 


1.09 


1.10 


1.05 


0.92 


1.08 


0.98 


1.08 


1.36 


1760 


1.10 


0.99 


1.22 


1.14 


1.03 


1.27 


1.09 


1.12 


0.81 


0.86 


1770 


0.75 


0.86 


0.97 


0.74 


0.93 


0.84 


0.97 


0.95 


0.93 


1.02 


1780 


1.18 


1.01 


0.82 


1.07 


1.21 


1.06 


1.13 


1.09 


0.90 


0.96 


1790 


1.02 


0.90 


1.18 


0.95 


1.05 


0.96 


1.03 


1.05 


1.15 


1.16 


1800 


0.92 


0.94 


1.05 


0.94 


0.80 


0.68 


0.78 


0.94 


0.80 


0.87 


1810 


1.01 


0.95 


0.92 


0.85 


0.99 + 


0.79 + 


0.89 + 


1.07 


0.83 


0.97 


1820 


0.90 


0.98 


0.90 


0.84 


0.94 


0.98 


0.94 


1.07 


0.86 


0.83 


1830 


0.96 


0.91 


1.04 


1.11 


1.07 


0.94 


0.73 


1.06 


0.90 


0.80 


1840 


0.90 


1.00 


0.73 


0.95 


1.03 


0.92 


0.85 


0.85 


1.05 


1.02 


1850 


0.88 


0.45 


0.81 


0.88 


0.90 


0.92 


0.97 


0.89 + 


0.84 


0.85 


1860 


0.90 


0.85 


1.01 


1.03 


1.04 


0.82 


1.07 


1.29 


1.09 


0.51 


1870 


1.47 


1.21 


1.17 


1.29 


1.36 


1.40 


1.57 


1.27 


1.32 


1.17 


1880 


1.00 


1.23 


1.00 


1.12 


1.15 


1.17 


1.35 


1.22 


1.34 


1.27 


1890 


1.02 


1.01 


1.01 


0.79 


0.84 


0.77 


1.01 


1.02 


1.07 


0.76 


1900 


0.94 


0.91 


0.87 


0.95 


0.83 


0.80 


0.73 


1.01 


0.69 


0.87 


1910 


1.01 


0.77 


0.85 


0.86 


0.79 + 


0.78 


0.95 


0.91 


1.02 


0.95 


1920 


0.77 










.... 
















APPENDIX 



147 



Pike's Peak, 9,500 Feet (PPB), S trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1690 








1.35 


1.07 


1.38 


1.14 


0.96 


1.18 


1.24 


1700 


1.26 


1.39 


1.04 


1.17 


1.06 


1.18 


1.22 


1.21 


1.26 


1.08 


1710 


1.30 


1.13 


1.25 


0.84 


1.13 


0.89 + 


1.00 


1.18 


1.26 


1.10 


1720 


1.13 


1.18 


1.22 


1.17 


1.15 


0.86 


0.87 


0.66 


0.84 


0.92 


1730 


0.88 


1.02 


1.02 


0.93 


1.07 


0.57 


0.72 


0.86 


0.92 


1.21 


1740 


1.32 


1.27 


0.68 


1.14 


0.99 


0.65 


1.19 


1.22 


0.74 


0.85 


1750 


0.76 


0.80 


0.72 


0.75 


0.23 


0.75 


0.62 


0.89 + 


0.79 


0.89 


1760 


0.67 


0.77 


0.99- 


0.24 


0.87 


0.71 


0.97 


0.98 


1.12 


1.23 


1770 


1.49 + 


1.37 


1.57 


1.84 


1.67 


1.17 


1.16 


1.31 


1.12 


1.23 


1780 


1.11 


0.85 


0.94 


1.03 


0.99 


1.30 


0.85 


0.88 


1.05 


0.32 


1790 


1.04 


0.81 


0.98 


1.06 


1.18 


1.09 


1.04 


1.07 


1.17 


0.96 


1800 


1.20 


0.80 


1.27 


0.82 


0.96 


0.75 


0.71 


0.86 


0.69 


0.74 


1810 


0.87 


0.75 


0.88 


0.86 


0.89 


0.88 


0.99 + 


0.99 + 


0.62 


0.77 


1820 


0.70 


0.53 


0.70 


0.66 


0.66 


1.07 


0.84 


0.83 


0.90 


0.75 


1830 


0.64 


0.91 


0.54 


0.95 


0.80 


0.88 


0.81 


0.87 


0.79 


0.67 


1840 


0.54 


0.49 


0.49 


0.60 


0.49 


0.43 


0.81 


0.68 


0.65 


0.45 


1850 


0.62 


0.15 


0.09 


0.24 


0.32 


0.54 


0.70 


0.69 


0.72 


0.64 


1860 


0.82 


0.62 


1.08 


0.85 


1.23 


0.96 


1.69 + 


1.08 


0.93 


1.60 


1870 


1.70 


1.27 


1.89 + 


2.19 


1.86 


1.68 


2.08 


1.50 


1.68 


1.17 


1880 


0.72 


1.14 


1.17 


1.53 


1.49 


1.59 


1.52 


1.59 + 


1.97 


2.13 


1890 


1.67 


1.74 


1.78 


0.79 


1.66 


1.67 


1.27 


1.33 


1.39 + 


0.55 


1900 


1.48 


1.58 


1.36 


1.56 


1.07 


1.37 


1.18 


1.12 


0.67 


1.21 


1910 


1.24 


1.24 


1.19 


1.18 


1.43 


1.31 


1.44 


1.04 


0.84 


0.90 


1920 


0.72 


.... 




.... 


















Pike's Peak, High North Transect (HNT), 10 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1650 












1.78 


1.72 


1.76 


1.56 


1.14 


1660 


1.85 


1.32 


1.42 


1.32 


6.99 


1.13 


0.76 


0.99 


0.55 


1.02 


1670 


0.78 


1.01 


1.10 


1.39 


1.19 


0.46 


0.78 


0.88 


1.25 


1.25 


1680 


1.82 


1.35 


0.41 


0.49 


0.62 


0.54 


0.88 


0.93 


1.07 


1.30 


1690 


0.68 


0.98 


1.50 


1.20 


0.72 


0.89 


0.92 


1.07 


0.83 


0.88 


1700 


0.87 


1.37 


1.37 


1.24 


1.13 


0.98 


1.33 


0.87 


1.02 


0.73 


1710 


1.34 


0.99 


1.43 


1.15 


1.52 


0.55 


0.74 


0.85 


1.04 


1.04 


1720 


1.36 


1.07 


1.09 


1.00 


1.11 


1.34 


1.58 


0.79 


1.14 


0.98 


1730 


0.54 


0.48 


0.76 


0.88 


0.87 


0.73 


0.65 


0.75 


0.83 


1.29 


1740 


1.09 


0.78 


0.36 


0.81 


0.81 


0.48 


1.11 


1.17 


0.48 


0.62 


1750 


0.69 


0.93 


0.69 


0.65 


0.56 


0.64 


0.42 


0.69- 


0.49 


0.71 


1760 


0.67 


1.16 


0.90 


0.62 


0.89- 


0.85 


1.24 


0.91 


1.60 


1.33 


1770 


1.37 


1.86 


1.59 + 


1.32 


1.19 + 


1.14 


1.27 


1.00 


0.86 


1.26+ 


1780 


0.74 + 


1.05 


0.81 


1.21 


1.09 + 


1.27 


1.12 


1.23 


1.39+ 


0.57 


1790 


1.37 


1.24 


1.17 


1.27 


1.11 


0.91 


1.19 + 


1.06 


0.79+ 


0.99+ 


1800 


1.31 


0.79 + 


1.37 + 


1.39- 


1.24 


0.63 


1.21 


1.20 


0.64- 


0.88- 


1810 


1.25- 


1.20 


1.29 


1.22 


1.48 


1.24 


1.23 


1.11 


0.71 


1.14+ 


1820 


0.70 


0.61 


0.57 


0.69 


0.40 


0.66 


0.90 + 


1.12 


1.28 


0.96 


1830 


0.80 


1.13 


0.65 


1.07 


1.05 


1.63 


1.29 + 


1.27 + 


1.58 


1.52 


1840 


1.73 


1.04 


0.98 + 


1.32 


1.22 


1.06 


1.16- 


0.91 


0.93 


0.91 


1850 


0.81- 


0.29- 


0.87 


0.81 


0.93 + 


1.02 


1.04 


1.31 


1.49 


1.12 


1860 


1.56 


0.85 + 


1.10 


0.64 


1.16 


0.69 


1.02 


1.04 


0.98 


1.41 


1870 


1.09 


0.88 + 


1.55 + 


1.19 


1.21 


1.04- 


1.41 


1.02- 


1.45 


0.96- 


1880 


0.41 


0.76- 


0.97 


1.07- 


0.71 


0.79 + 


0.77 


0.80 


0.80 


1.12 


1890 


0.93 


0.79 


0.76- 


0.59 + 


0.83 


1.03 


1.04 


0.84 + 


1.01 


0.32 + 


1900 


0.82 


0.78 


0.84 


0.97 


1.05 


0.83 


0.92 


1.05 


0.65- 


1.03 


1910 


0.93- 


0.84 


0.74 


0.88- 


0.92 


0.99 


0.89 


0.71 


0.86 + 


0.79 + 


1920 


0.61 





















148 



CLIMATIC CYCLES AND TREE-GROWTH 



Pike's Peak, Low North Transect (LNT), 7 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1640 


■ • 


.... 


.... 




0.72 


0.60 


0.98 


1.13 


1.10 


1.20 


1650 


0.68 


i.i8 


1.15 


1.13 


0.33 


1.33 


1.38 


1.33 


1.17 


0.56 


1660 


1.45 


1.48 


1.16 


1.00 


0.80 


1.32 


0.72 


0.89 


0.68 


0.87 


1670 


0.77 


1.18 


1.17 


1.22 


1.02 


0.57 


0.41 


0.48 


0.79 


0.70 


1680 


0.98 


0.55 


0.60 


0.72 


0.56 


0.33 


0.70 


0.73 


0.96 


1.06 


1690 


0.54 


0.81 


1.15 


0.98 


0.61 


0.87 


0.80 


1.05 


0.81 


0.81 


1700 


0.79 + 


0.89 + 


0.82 


0.89 


0.86 


1.00 


1.07 


0.92 


0.79 


0.95 


1710 


1.27 


0.89 


0.98 


0.96 


1.12 


0.67 


0.83 


0.68 


0.65 


1.17 


1720 


1.26 


1.25 


1.16 


0.86 


0.91 


0.75 


0.93 


0.76 


0.88 


0.79 


1730 


0.56 


0.39 


0.56 


0.59 


0.51 


0.56 


0.49 


0.51 


0.55 


0.83 


1740 


0.84 


0.82 


0.69 


0.89 


1.07 


0.72 


1.06 


1.02 


0.48 


0.69 + 


1750 


0.71 


0.82 


0.89 


1.10 


0.89 


1.03 


0.85 


1.29 


0.56 


0.69 + 


1760 


0.71 


0.89 


1.07 


0.87 


0.79 


0.73 


0.91 


0.80 


0.96 


0.72 


1770 


0.82 


1.00 


1.25 


1.20 


1.07 


0.84 


1.01 


0.90 


0.85 


0.90 


1780 


0.63 


0.93 


0.78 


0.93 


0.86 


0.86 


0.96 


1.04 


1.06 


0.52 


1790 


1.02 


0.98 


1.09 


0.98 


0.86 


0.88 


0.91 


0.81 


0.57 


0.86 


1800 


0.91 


0.70 


1.20 


1.09 


0.85 


0.71 


0.93 


0.99 


0.71 


0.69 


1810 


0.87 


0.75 


0.80 


0.85 


1.05 


0.88 


1.02 


1.14 


0.78 


0.78 


1820 


0.62 


0.58 


0.57 


0.51 


0.50 


0.70 


0.77 


0.98 


0.96 


0.80 


1830 


0.64 


0.91 


0.50 


0.73 


0.71 


0.68 


0.81 


0.90 


1.02 


0.86 


1840 


0.96 


0.66 


0.63 


0.77 


0.81 


0.68 


0.98 


0.79 + 


0.91 


0.75 


1850 


0.86 


0.24 


0.87 


0.96 


1.05 


1.16 


0.90 


1.08 


1.24 


1.09 + 


1860 


1.07 


0.69 


1.03 


0.58 


1.17 


0.83 


1.01 


1.09 


0.85 


1.32 


1870 


1.05 


0.85 


1.18 


1.19 


0.96 


0.93 


1.09 


0,92 


1.13 


0.71 


1880 


0.42 


0.88 


0.95 


0.86 


0.57 


0.68 


0.71 


0.76 


0.75 


0.73 


1890 


0.61 


0.78 


0.85 


0.64 


0.78 + 


0.82 


0.72 


0.92 


1.07 


0.39- 


1900 


0.90 


0.77 + 


0.88 + 


1.00 


0.98- 


0.87 


0.88 


0.87 + 


0.69 


1.11 


1910 


0.97 


0.79 


0.91 


1.04 


1.25 


1.21 


1.09 + 


0.91 


0.75 


0.95 + 


1920 


0.70 








.... 















Pike's Peak, South Transect (ST), 8 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1570 


1.40 


2.15 


2.03 


1.12 


1.37 


0.84 


0.73 


0.78 


0.70 


0.68 


1580 


0.61 


1.17 


0.93 


1.00 


1.09 


107 


1.20 


0.65 


0.63 


0.76 


1590 


0.92 


1.00 


0.90 


0.85 


0.95 


0.99 


0.81 


1.02 


0.92 


1.00 


1600 


1.18 


0.96 


0.91 


0.92 


1.35 


0.76 


0.73 


0.93 


0.73 


0.95 


1610 


1.19 


1.04 


0.66 


0.98 


0.72 


0.98 


0.98 


0.96 


1.19 


1.25 


1620 


0.91 


0.80 


0.85 


1.12 


1.19 


1.09 


1.10 


0.82 


0.95 


1.09 


1630 


1.10 


0.75 


1.36 


1.32 


1.36 


0.98 


1.13 


1.20 


0.25 


0.16 


1640 


0.36 


0.29 


0.42 


0.20 


0.36 


0.41 


0.55 


0.45 


0.66 


0.77 


1650 


0.80 


0.87 


0.64 


0.95 


0.82 


1.28 


1.27 


1.47 


1.41 


1.16 


1660 


1.44 


1.53 


1.44 


1.35 


1.08 


1.15 


0.97 


0.42 


0.32 


0.60 


1670 


0.53 


0.65 


0.68 


0.61 


0.78 


0.68 


0.27 + 


0.22 


0.52 


0.52 


1680 


0.46 


0.51 


0.70 


0.62 


0.74 


0.83 


0.96 


1.01 


1.14 


1.17 


1690 


1.43 


1.01 


1.25 


1.02 


0.95 


1.05 


1.15 


1.17 


1.27 


1.16 


1700 


1.48 


1.12 


1.19 


1.23 


1.42 


1.58 


1.28 


1.33 


1.18 


1.33 


1710 


1.49 


1.46 


1.38 


1.37 


1.84 


1.01 


0.95 


0.99 + 


1.27 


1.49 + 


1720 


1.45 


1.12 


0.78 


0.62 


0.89 


1.00 


1.01 


0.81 


0.95 


1.27 


1730 


1.35 


0.56 


0.22 


0.49 


0.49 


0.80 


0.63 


0.82 


0.86 


1.13 


1740 


1.05 


1.06 


0.91 


1.12 


0.98 


0.77 


0.82 


0.95 


0.88 


0.73 


1750 


0.62 


0.79 


0.72 


1.05 


0.68 


0.88 


1.25 


1.12 


0.09 


0.18 


1760 


0.55 


0.68 


0.74 


0.70 


0.73 


0.66 


0.77 


1.14 


0.84 


0.97 


1770 


0.73 


0.93 


1.14 


1.09 


1.07 


1.13 


1.49 


1.52 


1.44 


1.48 


1780 


1.01 


1.26 


0.99- 


1.20 


1.37 


1.29 


1.28- 


1.21 


1.54- 


1.30 


1790 


1.46 


1.30 


1.39 + 


1.65 


1.57 


1.60 


1.71 


1.25 


0.99 + 


1.17 


1800 


1.25 


0.91 


1.18 


1.17 


1.34 


1.19 


1.29 + 


1.31 


1.23 


1.36- 



APPENDIX 



149 







Pike'a Peak, 


South Transect (ST), 8 trees 


— Continued 






A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1810 


1.29 


1.35 


1.59 


1.34 


1.65 


1.42 


1.71 


1.70 


1.38 


1.14 


1820 


1.24 


1.11 


1.16 


1.31 


0.94- 


1.19- 


1.32 


1.42 


1.37 


1.11 


1830 


0.94 


1.17 


0.74 


0.88 + 


0.88+ 


1.07+ 


0.97 


1.04 


1.16- 


1.04 


1840 


1.09- 


1.04 


0.99 + 


1.06 


1.03 


0.89+ 


1.08- 


0.92 


0.90 


0.88 


1850 


0.98+ 


0.43- 


0.95 


0.96 


1.15 


1.07 


0.81 


0.95 + 


1.12 


0.78 


1860 


0.81 


0.77 


0.80 


0.66 


0.93 


0.76 


0.83 


0.81 


0.86 + 


0.89+ 


1870 


0.87- 


0.74 


0.89 


0.98 


0.81 


0.92 


0.99 + 


0.88 + 


1.11 


0.76- 


1880 


0.73 


0.76 


0.80 


0.59 + 


0.56 


0.50 


0.68 + 


0.76 


0.71 


0.73 


1890 


0.71 


0.82 


0.79 


0.80 


0.97 


0.95 


0.91 


0.99 + 


0.98 


0.49+ 


1900 


0.87 


0.71 


0.87 


1.05 


0.86 


0.81 


0.64 


0.67 


0.56 


0.79+ 


1910 


0.70 


0.63 


0.84 + 


0.91 


0.82 


0.87 


0.79 + 


0.73 


0.66 + 


0.76+ 


1920 


0.69 + 

























Pike's Peak, Brook, Douglas Fir and Pine (BDF), 


6 trees 






A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1780 






0.64 


0.61 


0.58 


0.88 


0.87 


1.18 


1.36 


0.73 


1790 


1.13 


1.37 


1.65 


1.20 


1.08 


1.10 


1.33 


1.28 


0.38 


0.32 


1800 


0.60 


0.59 


0.90 


1.01 


1.28 


0.87 


1.26 


1.33 


1.21 


1.03 


1810 


1.22 


1.07 


1.30 


1.11 


1.17 


1.15 


1.07 


0.89 


0.62 


0.80 


1820 


0.82 


0.73 


0.71 


0.67 


0.60 


0.83 


1.20 


1.32 


1.45 


1.33 


1830 


1.24 + 


1.22 


0.92 


0.97 


0.94 


1.00 


0.87 


1.05 


0.96 


1.05 


1840 


1.13 


0.67- 


0.64 


0.81 


0.84 


0.77 


0.84 


0.87 + 


0.96 


0.92 + 


1850 


0.90 


0.58+ 


1.05 


1.20 


1.41 


1.06 


0.73 


1.12 + 


1.39 + 


1.20 


1860 


1.15 


0.75 


1.02 


0.62 


0.90 


0.59 


0.97 


1.00 


0.78 


1.13 


1870 


0.94 


0.79 


0.90 


0.76 


0.93 


0.94 


0.99 


0.84 


0.93 


0.71 


1880 


0.35 


0.79- 


0.88 


0.76 


0.80 


0.77 


0.77 


0.70 


0.78 


0.83 


1890 


0.75 


0.76 


0.71 


0.58 


0.76 


0.94 


0.80 


0.94 


0.95 


0.46 


1900 


0.53- 


0.65+ 


0.67 


0.92 


1.10 


1.11 


0.94 


1.08 


0.53 


1.01 


1910 


1.03- 


0.68- 


0.81 


1.03- 


1.03- 


1.37 


1.25 


0.73 


0.64 


1.00 


1920 


0.63- 



























Pike's Peak 


, Brook, Engelmann Spruce 


(BES), 4 trees 






A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1770 












1.11 


0.78 


1.07 


1.09 


1.15 


1780 


1.35 


1.00 


1.39 


1.34 


1.12 


1.04 


1.04 


1.02 


0.92 


0.92 


1790 


1.04 


1.08 


1.43 


1.07 


1.11 


1.13 


1.12 


1.00 


0.98 


0.74 


1800 


1.11 


0.69 + 


0.99 


1.17 


1.05 


0.82 


0.88 + 


1.02 


0.78 


0.97 


1810 


0.87 


0.97 


1.00 


0.86 


1.00 


1.09 


1.07 


1.19 + 


1.00 


1.10 


1820 


0.73 


0.61 


0.56 


0.64 


0.46 


0.80 


1.07 


1.17 


1.31 


1.10 


1830 


0.95 


1.11 


0.74 


0.72 


0.81 


1.00 


1.19 


1.09 


1.15 


1.11 


1840 


1.17 + 


1.26 


0.92 


1.35 


1.14 


1.07 


1.02 


0.93 


0.84 


0.94 


1850 


0.87 


0.64 


0.74 


0.82 


0.97 


0.99 


0.66 


0.61 


0.81 


0.38 + 


1860 


0.72 


0.43 


0.63 


0.66 


0.70 


0.50 


0.60 


0.70 


0.80 


0.90 


1870 


1.09 + 


1.10 


1.10 


1.00 


1.03 + 


1.07 + 


1.09 


1.09 


1.42 


1.40 


1880 


1.16 


1.25 


0.94 


1.08 


1.05 


1.33 


1.09 


1.40 


1.32 + 


1.42 


1890 


1.06 


0.84 + 


0.79 


0.53 


0.71 


0.87 


0.83 + 


1.01 


1.12 


0.82 


1900 


1.28 


1.14 


1.15 


1.24 


0.85 


0.83 


0.62 


0.63 


0.74 + 


0.86 


1910 


0.76 + 


0.93 


0.64 


1.15 


1.16- 


1.26 


1.14 


0.71 


0.60 


0.73 


1920 


0.57 



















.... 





150 



CLIMATIC CYCLES AND TREE-GROWTH 









Cloudcroft, New Mexico (CC), S trees 








A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1730 














1.21 


1.27 


1.27 


0.90 


1740 


1.13 


1.73 


1.12 


1.60 


2.11 


2.23 


2.88 


3.49 


1.69 


2.11 


1750 


1.88 


2.62 


0.87 


2.10 


2.08 


2.42 


2.45 


3.02 


3.39 


2.81 


1760 


2.83 


3.46 


2.96 


1.67 


2.72 


2.87 


3.78 


2.06 


1.42 


2.70 


1770 


2.10 


2.48 


1.92 


2.13 


2.21 


1.96 


2.74 


2.34 


1.70 


2.47 


1780 


1.82 


1.92 


1.05 


1.48 


2.26 


1.48 


1.80 


2.37 


2.03 


1.33 


1790 


2.51 


2.29 


2.87 


3.11 


2.28 


1.58 


2.71 


1.97 


1.34 


2.40 


1800 


2.49 


1.91 


2.18 


2.42 


2.15 


2.62 


2.70 


1.83 


2.09 


1.78 


1810 


1.98 


2.00 


1.33 


2.01 


2.24 


2.86 


2.26 


1.42 


1.88 


0.95 


1820 


0.84 


0.66 


1.00 


1.39 


1.49 


1.30 


1.44 


1.96 


1.13 


1.96 


1830 


1.17 


0.91 


1.30 


1.35 


1.74 


1.22 


0.95 


0.54 


0.61 


0.90 


1840 


1.01 


0.70 


0.54 


0.58 


1.05 


0.91 


1.14 


0.45 


0.85 


0.71 


1850 


0.40 


0.38 


1.05 


1.08 


1.13 


0.68 


1.37 


0.92 


1.07 


0.32 


1860 


0.66 


1.38 


0.45 


1.09 


0.85 


0.96 


1.28 


1.12 


1.89 


2.14 


1870 


1.12 


1.52 


1.60 


1.24 


1.18 


1.38 


2.03 


1.31 


1.29 


1.13 


1880 


1.15 


1.28 


1.88 


1.66 


2.05 


2.13 


1.58 


2.04 


1.39 


1.51 


1890 


1.66 


1.32 


0.75 


0.56 


0.81 


1.06 


0.92 


1.20 


1.96 


1.08 


1900 


1.38 


1.19 


0.87 


1.41 


0.51 


1.11 


0.87 


1.48 


0.99 


0.73 


1910 


0.72 


1.25 


1.01 


1.20 


1.27 


0.70 


1.17 


1.38 


1.36 


1.32 


1920 


1.28 























Santa Fe, New Mexico (SF), 6 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1740 


















• • 


4.94 


1750 


3.12 


3.48 


3.72 


3.20 


5.18 


5.56 


2.72 


3.52 


2.80 


3.66 


1760 


2.80 


5.52 


4.70 


2.88 


5.00 


3.40 


4.94 


4.32 


2.64 


2.96 


1770 


1.98 


3.28 


2.38 


1.48 


2.08 


2.08 


2.12 


2.16 


2.40 


1.76 


1780 


2.24 


2.20 


2.10 


2.20 


1.70 


2.06 


2.00 


1.94 


1.60 


1.28 


1790 


1.24 


2.62 


2.36 


3.12 


2.42 


2.50 


2.64 


1.96 


2.30 


2.30 


1800 


2.56 


1.90 


2.30 


2.02 


2.50 


1.64 


1.38 


1.80 


2.32 


1.50 


1810 


1.98 


1.42 


1.32 


2.00 


1.70 


2.60 


2.74 


1.92 


1.46 


1.94 


1820 


2.32 


2.02 


1.16 


1.64 


1.64 


2.28 


2.24 


2.30 


2.42 


2.24 


1830 


2.20 


2.06 


2.36 


2.10 


2.82 


2.58 


2.20 


2.22 


2.78 


2.76 


1840 


2.54 


2.08 


0.90 


1.32 


2.12 


1.58 


1.92 


1.20 


1.14 


1.74 


1950 


1.58 


1.90 


2.56 


1.92 


2.64 


2.12 


2.12 


2.02 


2.34 


1.64 


1860 


1.56 


1.78 


1.76 


1.80 


1.42 


1.94 


2.68 


2.50 


3.02 


2.96 


1870 


2.22 


2.12 


2.38 


1.34 


1.90 


2.62 


2.06 


2.34 


2.18 


1.86 


1880 


1.02 


1.22 


1.96 


1.82 


2.50 


2.14 


2.40 


2.62 


1.98 


1.68 


1890 


1.28 


1.60 


1.80 


1.38 


1.84 


2.00 


1.24 


2.48 


1.96 


1.24 


1900 


1.92 


2.08 


1.42 


2.12 


0.72 


2.10 


2.02 


2.84 


2.64 


1.64 


1910 


1.62 


1.74 


1.84 


1.88 


2.10 


1.54 


2.06 


1.10 


1.24 


1.76 


1920 


1.64 


2.28 
























Modern H, 17, 22, 28, 24, 25, 26 (BMH), 6 trees 






A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1580 


















0.71 


1.02 


1590 


0.94 


1.36 


1.06 


1.12 


1.48 


2.10 


1.97 


2.04 


2.08 


2.99 


1600 


1.78 


2.14 


2.64 


2.87 


3.41 


3.36 


3.14 


2.77 


3.13 


2.77 


1610 


3.48 


3.56 


2.70 


2.59 


2.67 


2.67 


2.48 


2.30 


2.39 


2.68 


1620 


2.26 


2.81 


1.86 


1.39 


1.66 


2.30 


1.94 


2.72 


2.28 


2.73 


1630 


1.84 


1.13 


1.04 


1.82 


2.01 


2.13 


2.26 


2.07 


1.35 


1.87 


1640 


2.52 


1.90 


1.58 


1.60 


2.87 


2.13 


2.54 


2.05 


1.64 


1.86 



APPENDIX 



151 







Modern H, 17, 22, 23, 24, 25, 26 (BMH), 6 trees— Continued 






A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1650 


2.32 


2.14 


2.25 


2.38 


1.70 


2.57 


2.30 


1.80 


1.47 


1.63 


1660 


1.81 


2.22 


1.97 


1.72 


1.34 


1.61 


1.18 


1.18 


1.03 


1.34 


1670 


1.18 


1.62 


2.77 


1.84 


1.60 


1.72 


0.95 


1.38 


1.50 


1.74 


1680 


2.06 


2.05 


1.38 


2.08 


1.41 


0.18 


1.31 


1.92 


2.36 


2.18 


1690 


1.65 


1.42 


1.95 


1.44 


1.35 


1.41 


1.02 


1.38 


1.34 


1.91 


1700 


1.50 


2.18 


1.50 


1.12 


1.16 


1.92 


1.72 


0.99 


1.32 


1.72 


1710 


1.48 


1.73 


1.22 


1.47 


1.30 


1.47 


1.32 


1.33 


1.48 


1.42 


1720 


1.79 


1.59 


1.54 


1.78 


1.60 


2.10 


1.87 


1.31 


1.45 


0.75 


1730 


0.74 


0.81 


0.86 


0.79 


1.06 


0.28 


0.54 


0.59 


0.82 


0.78 


1740 


0.72 


0.79 


0.97 


1.21 


1.06 


1.50 


1.67 


1.78 


0.42 


1.36 


1750 


1.44 


1.04 


0.91 


1.15 


1.23 


0.59 


0.62 


0.67 


0.76 


1.12 


1760 


1.01 


1.27 


1.48 


1.48 


1.68 


1.24 


1.63 


1.64 


1.40 


0.97 


1770 


1.30 


1.57 


1.58 


0.61 


1.12 


0.80 


0.79 


0.79 


0.71 


0.72 


1780 


0.64 


0.67 


0.74 


0.81 


1.08 


0.56 


0.84 


0.97 


0.60 


0.80 


1790 


0.81 


1.13 


1.05 


1.25 


1.24 


1.10 


0.91 


0.91 


1.02 


1.12 


1800 


1.35 


1.06 


1.28 


1.05 


0.88 


0.91 


0.77 


0.77 


0.66 


0.75 


1810 


0.87 


0.90 


0.81 


0.43 


0.65 


1.03 


1.07 


0.72 


0.16 


0.45 


1820 


0.36 


0.48 


0.26 


0.25 


0.50 


0.51 


0.61 


0.48 


0.85 


0.67 


1830 


1.02 


0.87 


0.81 


0.90 


0.70 


0.84 


0.82 


0.82 


0.87 


0.92 


1840 


0.88 


1.00 


0.71 


0.85 


0.76 


0.76 


0.69 


0.07 


0.66 


0.87 


1850 


0.71 


0.30 


0.87 


0.95 


0.65 


0.66 


0.65 


0.89 


0.89 


0.54 


1860 


0.80 


0.16 


0.85 


0.72 


0.33 


0.72 


0.89 


0.91 


1.23 


1.19 


1870 


0.73 


0.32 


0.62 


0.72 


0.62 


0.92 


0.72 


0.85 


0.92 


0.45 


1880 


0.68 


0.76 


0.57 


0.65 


0.76 


0.93 


0.68 


0.87 


0.84 


0.72 


1890 


0.84 


0.94 


0.78 


0.59 


0.60 


0.59 


0.37 


0.74 


0.70 


0.39 


1900 


0.28 


0.42 


0.12 


0.75 


0.37 


0.78 


0.70 


1.04 


1.12 


1.02 


1910 


1.16 


1.14 


0.82 


0.82 


1.06 


0.94 


1.05 


0.82 


0.81 


0.72 









Modern H, 27 


, 28 (BML), 2 trees 








A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1700 


1.28 


1.25 


1.76 


1.28 


0.96 


1.23 


1.59 


0.97 


1.15 


1.21 


1710 


1.70 


1.99 


1.72 


1.65 


1.34 


1.50 


1.57 


1.47 


1.84 


2.55 


1720 


2.96 


3.07 


3.26 


2.78 


2.74 


4.00 


4.06 


2.88 


3.04 


1.75 


1730 


3.75 


3.26 


3.20 


3.55 


3.39 


1.26 


1.99 


1.94 


2.67 


2.02 


1740 


1.94 


1.82 


2.49 


2.61 


2.94 


3.43 


4.32 


3.48 


1.56 


3.11 


1750 


2.44 


1.98 


1.99 


1.74 


2.37 


1.19 


1.35 


1.37 


1.61 


2.27 


1760 


2.13 


2.00 


2.83 


2.17 


2.47 


1.72 


2.57 


2.66 


2.75 


1.77 


1770 


1.84 


2.79 


2.85 


1.28 


1.82 


1.50 


1.37 


1.11 


1.37 


1.13 


1780 


1.13 


1.36 


1.38 


1.75 


2.02 


1.05 


1.58 


2.21 


1.12 


1.11 


1790 


1.48 


1.69 


1.59 


2.28 


1.88 


1.65 


1.08 


1.31 


1.46 


1.67 


1800 


1.84 


1.24 


2.03 


1.43 


1.65 


1.43 


1.31 


1.35 


1.57 


1.03 


1810 


1.33 


1.66 


1.41 


1.07 


1.49 


1.85 


1.72 


1.52 


0.64 


0.94 


1820 


0.82 


0.71 


0.27 


0.31 


0.62 


0.68 


1.02 


0.98 


1.46 


1.05 


1830 


1.70 


1.08 


1.57 


1.31 


1.31 


1.41 


1.37 


1.58 


1.56 


1.53 


1840 


1.33 


1.67 


1.25 


1.32 


1.09 


1.17 


0.83 


0.35 


0.70 


1.04 


1850 


0.75 


0.39 


1.07 


1.12 


0.91 


0.94 


1.05 


1.22 


0.92 


0.66 


1860 


1.20 


0.44 


1.14 


0.80 


0.50 


0.96 


1.28 


1.09 


1.22 


1.39 


1870 


1.10 


0.40 


0.67 


0.74 


0.66 


1.24 


0.57 


1.08 


1.17 


0.68 


1880 


0.80 


1.17 


0.88 


0.66 


1.28 


1.39 


0.88 


1.36 


1.40 


1.13 


1890 


1.43 


1.29 


1.15 


0.90 


0.81 


0.71 


0.51 


0.98 


0.84 


0.41 


1900 


0.33 


0.48 


0.02 


0.81 


0.26 


0.75 


0.84 


1.51 


1.45 


1.37 


1910 


1.37 


1.64 


1.33 


1.28 


1.61 


1.47 


1.70 


0.88 







11 



152 



CLIMATIC CYCLES AND TREE-GROWTH 









Modern H, 89 


40,41,42 (AE), 4 trees 








A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1660 






2.30 


1.50 


1.20 


2.25 


0.72 


0.82 


0.72 


0.45 


1670 


6.79 


1.13 


1.21 


1.40 


1.70 


1.43 


0.83 


1.24 


1.72 


1.06 


1680 


1.81 


1.72 


1.31 


1.67 


0.85 


0.17 


1.80 


1.68 


1.23 


1.87 


1690 


2.55 


1.60 


2.55 


2.63 


1.61 


1.40 


0.90 


1.30 


1.97 


2.42 


1700 


1.79 


2.37 


1.20 


1.38 


0.98 


1.64 


2.07 


1.07 


1.54 


1.41 


1710 


2.49 


2.01 


1.46 


1.04 


0.76 


1.22 


1.00 


1.24 


1.75 


1.70 


1720 


2.30 


1.78 


1.30 


1.67 


0.97 


1.30 


1.90 


2.04 


1.66 


0.29 


1730 


0.95 


1.16 


1.51 


1.21 


1.45 


0.36 


1.04 


0.77 


0.96 


1.00 


1740 


0.86 


0.90 


0.77 


1.16 


0.80 


1.08 


1.45 


1.98 


0.61 


1.82 


1750 


1.26 


1.06 


0.93 


0.72 


1.21 


0.82 


0.70 


0.69 


0.71 


0.81 


1760 


0.73 


0.73 


0.96 


0.93 


0.99 


0.66 


1.50 


0.85 


1.26 


1.10 


1770 


1.44 


1.56 


1.18 


0.34 


0.84 


0.95 


0.55 


0.53 


0.66 


0.57 


1780 


0.52 


0.68 


0.58 


0.77 


0.75 


0.68 


0.70 


0.97 


0.52 


0.40 


1790 


0.47 


0.63 


0.76 


0.91 


0.48 


0.66 


0.64 


0.44 


0.52 


0.59 


1800 


0.62 


0.31 


0.86 


0.60 


0.62 


0.43 


0.24 


0.66 


0.59 


0.62 


1810 


0.42 


0.75 


0.80 


0.54 


0.63 


1.09 


1.44 


1.29 


0.37 


0.40 


1820 


0.31 


1.00 


0.43 


0.41 


0.35 


0.58 


0.56 


0.39 


0.87 


0.68 


1830 


0.90 


0.86 


1.25 


1.19 


0.86 


0.93 


0.64 


0.70 


0.83 


1.11 


1840 


1.12 


1.01 


0.84 


0.76 


0.54 


0.59 


0.69 


0.04 


0.76 


0.66 


1850 


0.76 


0.25 


0.77 


0.92 


0.68 


0.66 


0.67 


0.48 


0.65 


0.45 


1860 


0.60 


0.02 


0.69 


0.39 


0.10 


0.38 


0.37 


0.55 


0.65 


0.85 


1870 


0.40 


0.00 


0.42 


0.25 


0.43 


0.44 


0.43 


0.10 


0.46 


0.26 


1880 


0.26 


0.29 


0.27 


0.25 


0.38 


0.21 


0.39 


0.52 


0.59 


0.44 


1890 


0.69 


0.69 


0.73 


0.74 


0.54 


0.27 


0.24 


0.35 


0.16 


0.46 


1900 


0.37 


1.12 


0.25 


0.26 


0.32 


0.38 


0.32 


0.44 


0.38 


0.38 


1910 


0.37 


0.53 


0.66 


0.35 


0.80 


0.85 


0.99 


0.92 


0.52 


0.84 



COAST ZONE 
Boise, Idaho (BI), 10 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1650 






1.70 


0.65 


1.50 


1.65 


2.05 


1.05 


1.70 


2.05 


1660 


1.70 


1.75 


1.30 


1.50 


1.30 


1.00 


1.60 


1.40 


0.90 


1.50 


1670 


1.80 


1.75 


1.15 


1.60 


0.90 


1.15 


0.90 


0.80 


0.80 


1.25 


1680 


0.75 


1.25 


1.10 


1.20 


1.20 


1.05 


1.00 


1.40 


1.40 


1.25 


1690 


2.00 


1.75 


2.15 


2.45 


3.55 


2.35 


1.95 


2.45 


2.15 


2.15 


1700 


2.20 


2.05 


3.15 


3.20 


1.85 


2.30 


2.90 


2.40 


1.75 


1.60 


1710 


2.05 


1.85 


1.95 


1.75 


1.10 


0.90 


1.35 


0.95 


1.10 


1.00 


1720 


1.50 


0.50 


0.60 


0.95 


0.80 


0.75 


0.80 


1.00 


0.75 


0.50 


1730 


0.50 


0.85 


1.20 


1.05 


1.00 


1.20 


1.00 


1.45 


1.60 


1.00 


1740 


1.00 


1.35 


0.90 


1.35 


1.05 


1.35 


1.75 


1.50 


1.45 


1.45 


1750 


1.95 


2.20 


2.35 


1.60 


1.64 


2.28 


1.80 


1.58 


2.21 


2.09 


1760 


1.98 


2.91 


2.79 


2.33 


2.06 


2.45 


2.51 


2.88 


2.51 


2.05 


1770 


1.98 


1.98 


2.28 


1.12 


0.81 


1.28 


1.65 


1.81 


1.32 


1.42 


1780 


1.80 


1.48 


1.74 


1.38 


1.14 


1.62 


1.63 


1.29 


1.57 


1.55 


1790 


1.67 


1.99 


2.19 


1.98 


1.56 


1.27 


1.37 


1.15 


0.93 


1.36 


1800 


1.53 


1.57 


1.49 


1.44 


1.45 


1.61 


1.59 


0.97 


1.11 


1.15 


1810 


0.60 


0.70 


1.02 


0.98 


1.18 


1.10 


1.12 


1.00 


1.15 


1.15 


1820 


1.15 


1.23 


1.11 


1.20 


1.09 


1.07 


0.97 


1.08 


1.25 


1.18 


1830 


1.06 


0.83 


1.36 


1.01 


0.87 


1.00 


1.02 


1.01 


1.00 


0.91 


1840 


0.77 


0.88 


0.92 


0.79 


0.74 


0.89 


0.85 


0.79 


0.72 


0.70 


1850 


0.82 


0.79 


0.71 


0.68 


0.99 


0.83 


0.67 


0.93 


0.88 


0.64 


1860 


0.94 


1.06 


0.90 


0.76 


0.72 


0.68 


0.90 


0.78 


0.92 


0.91 


1870 


0.70 


0.71 


0.88 


0.91 


0.84 


0.91 


0.93 


0.94 


0.94 


0.96 


1880 


0.73 


0.82 


0.70 


0.60 


0.80 


1.07 


0.71 


0.85 


0.76 


0.48 


1890 


0.45 


0.69 


0.78 


0.53 


0.63 


0.72 


0.64 


0.36 


0.59 


0.62 


1900 


0.83 


0.87 


0.85 


0.85 


0.76 


0.75 


0.59 


0.68 


0.86 


0.87 


1910 


0.86 


0.87 


0.78 


0.79 


0.63 


0.58 


0.52 


0.42 


0.74 


0.93 


1920 


0.64 


0.79 


0.75 

















APPENDIX 

Boise, Idaho, 8 trees selected 



153 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1650 






1.70 


0.65 


1.50 


1.65 


2.05 


1.05 


1.70 


2.05 


1660 


i.Vo 


1.75 


1.30 


1.50 


1.30 


1.00 


1.60 


1.40 


0.90 


1.50 


1670 


1.80 


1.75 


1.15 


1.60 


0.90 


1.15 


0.90 


0.80 


0.80 


1.25 


1680 


0.75 


1.25 


1.10 


1.20 


1.20 


1.05 


1.00 


1.40 


1.40 


1.25 


1690 


2.00 


1.75 


2.15 


2.45 


3.55 


2.35 


1.95 


2.45 


2.15 


2.15 


1700 


2.20 


2.05 


3.15 


3.20 


1.85 


2.30 


2.90 


2.40 


1.75 


1.60 


1710 


2.05 


1.85 


1.95 


1.75 


1.10 


0.90 


1.35 


0.95 


1.10 


1.00 


1720 


1.50 


0.50 


0.60 


0.95 


0.80 


0.75 


0.80 


1.00 


0.75 


0.50 


1730 


0.50 


0.85 


1.20 


1.05 


1.00 


1.20 


1.00 


1.45 


1.60 


1.00 


1740 


1.00 


1.35 


0.90 


1.35 


1.05 


1.35 


1.75 


1.50 


1.45 


1.45 


1750 


1.95 


2.20 


2.35 


1.60 


1.64 


2.28 


1.80 


1.58 


2.22 


2.09 


1760 


1.98 


2.91 


2.79 


2.33 


2.06 


2.45 


2.51 


2.82 


2.51 


2.05 


1770 


1.98 


1.98 


2.28 


2.15 


0.84 


1.32 


1.71 


1.88 


1.37 


1.49 


1780 


1.89 


1.50 


1.80 


1.63 


1.12 


1.88 


1.80 


1.39 


1.53 


1.65 


1790 


1.23 


2.45 


2.45 


2.36 


1.89 


1.49 


1.72 


1.45 


1.15 


1.63 


1800 


1.74 


1.55 


1.63 


1.72 


2.01 


1.96 


2.05 


1.20 


0.93 


0.83 


1810 


0.25 


0.33 


0.59 


0.68 


1.10 


1.18 


1.26 


1.23 


1.41 


1.41 


1820 


1.28 


1.45 


1.78 


1.33 


1.36 


1.42 


1.56 


1.45 


1.70 


1.80 


1830 


1.42 


0.90 


1.82 


1.78 


1.12 


1.10 


1.20 


1.25 


1.48 


1.18 


1840 


0.92 


1.25 


1.25 


0.95 


0.75 


0.78 


0.78 


0.35 


0.48 


0.58 


1850 


0.65 


0.68 


0.42 


0.82 


1.08 


0.81 


0.75 


0.93 


0.82 


0.63 


1860 


0.88 


0.95 


0.94 


0.92 


0.81 


0.77 


1.03 


1.03 


1.11 


1.09 


1870 


0.81 


0.78 


0.82 


0.91 


1.15 


1.14 


1.03 


1.16 


1.17 


1.12 


1880 


1.05 


0.93 


0.73 


0.60 


0.73 


1.07 


0.87 


0.92 


0.91 


0.42 


1890 


0.41 


0.65 


0.72 


0.40 


0.53 


0.55 


0.39 


0.16 


0.45 


0.40 


1900 


0.36 


0.49 


0.62 


0.41 


0.63 


0.61 


0.49 


0.55 


0.85 


0.80 


1910 


0.68 


0.85 


0.46 


0.62 


0.58 


0.59 


0.50 


0.31 


0.66 


0.90 


1920 


0.65 


0.41 


0.55 

















Baker, Oregon (BO) , 7 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1660 


1.60 


1.65 


0.55 


1.10 


1.25 


1.10 


2.00 


2.40 


2.00 


2.10 


1670 


2.85 


3.35 


2.70 


2.20 


2.20 


1.90 


1.45 


1.25 


1.80 


1.65 


1680 


0.90 


1.00 


1.00 


0.90 


1.25 


1.35 


1.60 


1.25 


1.35 


1.60 


1690 


1.35 


1.45 


1.45 


1.00 


1.50 


1.20 


1.20 


1.45 


1.05 


0.80 


1700 


0.75 


0.60 


0.80 


1.00 


0.95 


1.30 


1.80 


1.65 


1.50 


1.70 


1710 


2.80 


3.20 


2.95 


2.40 


1.75 


2.70 


2.40 


1.50 


1.65 


1.00 


1720 


1.25 


0.90 


1.10 


1.10 


1.10 


1.65 


2.10 


2.20 


1.45 


1.55 


1730 


1.90 


1.60 


1.75 


1.75 


1.25 


1.70 


1.50 


2.10 


1.60 


1.20 


1740 


1.25 


1.35 


1.05 


1.05 


1.25 


1.45 


1.25 


1.10 


1.10 


1.30 


1750 


1.35 


1.20 


1.30 


0.85 


0.85 


0.80 


0.50 


0.65 


0.65 


0.45 


1760 


1.15 


1.20 


0.80 


0.75 


0.74 


0.64 


0.90 


0.82 


0.78 


0.78 


1770 


0.88 


0.97 


1.02 


0.98 


1.06 


0.90 


0.75 


0.64 


0.85 


0.95 


1780 


1.10 


0.84 


0.86 


0.78 


0.66 


0.47 


0.79 


0.72 


0.86 


1.04 


1790 


1.13 


1.74 


1.92 


1.55 


1.70 


1.50 


1.79 


1.02 


1.32 


1.29 


1800 


1.18 


1.16 


1.14 


1.14 


0.91 


1.03 


0.90 


0.82 


0.89 


1.11 


1810 


1.04 


1.04 


1.64 


1.42 


1.66 


1.23 


1.24 


1.09 


1.22 


1.64 


1820 


1.17 


1.23 


1.65 


0.87 


1.58 


1.84 


1.53 


0.89 


1.08 


0.93 


1830 


0.87 


1.18 


1.15 


1.05 


0.89 


0.89 


1.21 


1.38 


1.67 


1.69 


1840 


1.14 


1.11 


0.83 


0.70 


0.77 


1.12 


0.94 


0.59 


0.84 


0.78 


1850 


0.57 


0.81 


0.77 


0.87 


0.88 


1.23 


0.97 


1.16 


1.23 


1.00 


1860 


1.00 


1.19 


1.06 


1.12 


1.18 


1.29 


1.87 


1.39 


1.66 


1.32 


1870 


1.28 


1.20 


1.26 


1.52 


1.29 


1.35 


1.79 


2.03 


1.89 


1.71 


1880 


1.39 


1.72 


1.29 


0.98 


1.08 


1.44 


1.05 


1.05 


1.18 


0.87 


1890 


0.75 


1.02 


0.85 


0.72 


1.16 


0.95 


1.01 


1.16 


1.21 


0.80 


1900 


1.23 


1.09 


0.99 + 


1.06 


1.17 


1.02 


0.91 


1.10 


0.93 


0.94 


1910 


0.76 


0.69 


0.81 


1.05 


0.78 


0.82 


0.95 


0.60 


0.65 


0.71 


1920 


0.61 


0.76 


0.32 


0.60 


0.52 













154 



CLIMATIC CYCLES AND TREE-GROWTH 



The Dalles, Oregon (DL), S trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1760 












3.00 


3.30 


3.50 


1.94 


2.72 


1770 


1.55 


1.93 


2.23 


1.72 


1.68 


1.57 


0.87 


0.92 


0.93 


1.10 


1780 


0.75 


0.98 


1.30 


1.18 


0.99 


0.90 


1.64 


1.01 


0.82 


0.88 


1790 


0.97 


0.81 


1.20 


1.18 


0.84 


0.60 


0.49 


0.58 


1.10 


1.18 


1800 


1.11 


1.12 


1.25 


0.93 


0.79 


1.10 


1.25 


1.26 


1.68 


1.43 


1810 


1.39 


1.39 


1.56 


1.81 


1.45 


1.35 


1.18 


1.15 


0.80 


1.28 


1820 


1.21 


1.05 


0.93 


0.81 


0.82 


0.84 


0.99 


1.25 


0.88 


1.15 


1830 


1.25 


1.08 


1.00 


1.35 


1.12 


1.21 


1.00 


0.88 


0.99 


0.67 


1840 


0.68 


0.44 


0.66 


0.92 


0.74 


1.02 


0.98 


0.54 


0.48 


0.34 


1850 


0.63 


0.42 


0.65 


0.69 


0.94 


0.88 


0.96 


1.02 


1.05 


1.05 


1860 


1.21 


1.08 


1.09 


1.17 


1.63 


1.06 


1.23 


1.12 


1.07 


1.07 


1870 


1.30 


1.23 


1.39 


1.09 


1.18 


0.74 


1.24 


1.11 


1.03 


1.01 


1880 


1.16 


1.00 


1.34 


1.12 


1.23 


1.16 


1.19 


1.01 


0.77 


0.68 


1890 


0.55 


0.37 


0.38 


0.39 


0.54 


0.73 


0.95 


1.38 


1.21 


1.03 


1900 


1.14 


1.13 


0.85 


1.09 


1.13 


0.79 


0.85 


0.82 


1.14 


0.79 


1910 


0.66 


0.70 


0.83 


0.97 


0.85 


0.91 


0.89 


0.92 


0.74 


0.70 


1920 


0.68 


1.12 


0.89 


0.68 


1.05 













Oregon Coast (OCT) 
(See Volume I, Appendix, page 117) 









Klamath Falls 


, Oregon 


[KF), It trees 








A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1790 






1.01 


1.17 


0.83 


0.69 


0.75 


1.16 


1.25 


1.74 


1800 


1.02 


1.05 


1.32 


1.23 


1.12 


1.23 


1.44 


1.18 


1.15 


1.35 


1810 


1.14 


1.18 


0.94 


1.93 


0.94 


0.86 


0.91 


0.96 


1.16 


1.15 


1820 


0.93 


0.95 


0.81 


0.83 


0.56 


0.92 


0.91 


0.86 


0.94 


0.61 


1830 


1.05 


1.08 


1.47 


0.87 


0.91 


1.47 


1.64 


1.51 


1.43 


0.48 


1840 


1.08 


0.57 


0.73 


0.63 


0.35 


0.76 


0.50 


0.69 


0.81 


0.72 


1850 


0.91 


0.97 


0.84 


1.21 


0.94 


1.00 


0.85 


0.94 


0.79 


0.69 


1860 


1.10 


1.35 


0.99 


0.99 


0.98 


0.84 


1.01 


1.03 


1.09 


0.42 


1870 


0.72 


0.54 


0.66 


0.85 


0.91 


0.80 


1.08 


1.05 


1.15 


0.98 


1880 


0.85 


1.12 


0.81 


0.93 


1.13 


1.04 


0.96 


1.04 


0.99 


0.32 


1890 


0.69 


0.79 


0.85 


1.14 


1.56 


1.12 


1.12 


1.21 


0.35 


0.79 


1900 


0.92 


1.04 


0.99 


1.20 


1.19 


0.92 


0.95 


1.12 


1.00 


1.19 


1910 


1.19 


0.94 


1.08 


1.33 


1.23 


0.77 


1.18 


0.86 


0.50 


0.76 


1920 


0.31 


0.61 


0.51 


0.75 















Meadow Valley Pines, Plumas County, California (CP), 9 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1550 




2.13 


1.95 


1.80 


1.98 


2.91 


2.37 


1.80 


1.50 


1.17 


1560 


1.26 


1.47 


1.62 


1.77 


1.68 


1.92 


1.11 


0.93 


1.26 


1.20 


1570 


0.90 


1.59 


1.32 


1.26 


1.53 


1.68 


2.19 


1.29 


1.38 


0.93 


1580 


1.02 


1.05 


1.23 


1.35 


1.17 


1.23 


1.26 


1.23 


0.75 


0.36 


1590 


0.90 


1.05 


0.90 


0.42 


0.24 


0.51 


0.75 


0.90 


0.90 


0.87 


1600 


1.17 


1.11 


1.50 


0.99 


0.75 


1.20 


1.23 


1.20 


1.05 


1.08 


1610 


1.80 


1.44 


0.96 


1.50 


1.53 


1.20 


1.50 


1.83 


1.44 


1.80 


1620 


1.95 


1.35 


1.53 


2.40 


1.80 


1.74 


1.50 


2.76 


1.80 


2.31 


1630 


2.19 


1.80 


2.01 


2.46 


3.66 


3.51 


3.54 


4.50 


3.03 


2.64 


1640 


2.88 


3.60 


3.09 


3.84 


4.02 


2.91 


3.84 


3.39 


2.55 


3.21 


1650 


3.24 


3.69 


2.70 


2.67 


2.76 


3.66 


3.42 


2.94 


3.12 


3.63 


1660 


2.43 


3.30 


3.30 


2.40 


3.30 


2.79 


3.15 


3.51 


2.94 


3.27 



APPENDIX 



155 









Meadow Valley Pines (CP), 


9 trees — 


Continued 






A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1670 


2.88 


2.67 


3.00 


3.72 


3.42 


3.48 


2.88 


2.97 


3.09 


3.24 


1680 


3.12 


3.75 


3.39 


2.82 


3.27 


3.57 


3.39 


2.94 


3.18 


2.16 


1690 


2.52 


3.48 


3.18 


2.58 


3.78 


2.97 


2.79 


2.79 


2.73 


3.12 


1700 


3.12 


2.16 


2.64 


2.88 


2.97 


2.97 


2.73 


2.97 


3.03 


2.67 


1710 


3.21 


2.22 


2.67 


2.49 


2.85 


3.30 


3.75 


3.54 


3.21 


2.82 


1720 


3.24 


2.85 


3.18 


3.03 


2.46 


2.61 


3.21 


2.85 


2.61 


2.82 


1730 


3.12 


3.03 


2.88 


2.49 


2.67 


2.82 


3.12 


2.61 


3.21 


2.97 


1740 


2.58 


2.61 


2.61 


3.06 


2.70 


2.64 


2.43 


2.76 


2.37 


2.85 


1750 


2.82 


2.85 


2.52 


2.64 


3.03 


3.15 


2.49 


2.58 


2.76 


3.12 


1760 


2.37 


2.97 


2.55 


2.10 


2.25 


2.64 


2.49 


2.37 


2.46 


2.13 


1770 


2.52 


2.28 


2.46 


2.70 


2.85 


2.97 


2.49 


2.07 


2.67 


2.64 


1780 


3.30 


2.73 


2.70 


2.97 


2.73 


2.97 


3.18 


2.37 


2.70 


2.43 


1790 


2.52 


2.91 


3.42 


3.33 


3.06 


2.91 


2.31 


2.70 


3.63 


3.39 


1800 


3.66 


3.33 


2.91 


3.30 


3.78 


3.63 


3.57 


3.72 


4.11 


4.56 


1810 


4.74 


4.44 


4.92 


3.99 


4.17 


3.30 


3.51 


3.21 


3.57 


3.57 


1820 


3.33 


2.49 


2.58 


1.68 


1.89 


2.37 


2.76 


2.70 


2.43 


2.91 


1830 


1.95 


2.13 


2.91 


2.46 


2.25 


2.46 


2.40 


2.82 


2.37 


2.31 


1840 


2.85 


3.09 


2.70 


3.06 


2.82 


3.63 


3.51 


2.94 


2.25 


1.83 


1850 


2.19 


2.58 


2.67 


2.43 


2.43 


3.00 


2.58 


2.61 


2.19 


2.16 


1860 


2.70 


2.61 


2.10 


2.34 


2.19 


2.25 


2.49 


3.18 


2.82 


3.18 


1870 


3.39 


3.36 


3.48 


3.27 


2.70 


2.79 


2.34 


2.73 


2.43 


2.58 


1880 


2.01 


2.70 


1.71 


1.68 


1.95 


2.31 


1.59 


1.79 


1.83 


1.65 


1890 


1.59 


1.89 


1.89 


2.10 


2.31 


1.83 


2.04 


1.98 


1.77 


1.92 


1900 


2.67 


2.10 


2.13 


2.16 


2.01 


2.07 


2.07 


2.19 


2.16 


1.98 


1910 


1.59 


1.77 


2.28 


2.22 


2.07 


1.77 


1.74 


1.62 


1.65 


1.68 


1920 


1.59 


1.92 
















.... 



Calaveras Pines (CVP), 14 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1620 




1.60 


1.70 


1.40 


1.30 


1.15 


1.95 


1.35 


1.40 


1.65 


1630 


1.55 


0.90 


1.15 


1.40 


1.45 


1.55 


1.90 


2.45 


2.10 


1.45 


1640 


1.20 


1.40 


1.45 


1.75 


1.80 


1.80 


1.80 


2.20 


1.90 


1.45 


1650 


1.95 


1.50 


1.50 


0.60 


1.65 


0.70 


1.60 


1.05 


0.90 


1.15 


1660 


1.85 


1.50 


1.70 


2.05 


1.15 


1.10 


1.75 


1.80 


0.95 


1.88 


1670 


1.93 


1.83 


1.65 


2.15 


1.70 


1.83 


1.58 


1.88 


1.88 


1.65 


1680 


1.60 


2.90 


2.08 


1.35 


2.00 


2.75 


1.95 


1.65 


2.03 


1.40 


1690 


1.48 


1.95 


1.35 


1.53 


2.25 


2.20 


1.88 


1.55 


1.50 


2.52 


1700 


1.95 


1.20 


1.32 


2.41 


2.00 


2.90 


2.48 


2.00 


2.12 


2.58 


1710 


2.81 


1.89 


2.78 


2.31 


2.57 


2.14 


2.05 


2.04 


1.70 


1.59 


1720 


1.85 


1.85 


1.67 


2.32 


2.11 


1.68 


2.30 


2.10 


1.56 


1.12 


1730 


1.62 


1.65 


1.56 


1.36 


1.42 


1.20 


1.78 


1.28 


1.56 


1.69 


1740 


1.59 


2.21 


1.71 


1.26 


1.46 


1.34 


1.55 


1.63 


1.31 


1.86 


1750 


1.97 


1.91 


1.75 


1.74 


1.26 


1.74 


1.35 


1.15 


1.83 


1.88 


1760 


1.60 


2.14 


1.73 


1.14 


1.32 


1.42 


1.84 


1.31 


1.77 


1.54 


1770 


2.24 


1.69 


2.14 


2.06 


1.81 


1.77 


1.46 


1.05 


1.14 


1.18 


1780 


1.16 


0.95 


1.24 


1.12 


1.30 


1.69 


1.39 


1.03 


1.53 


1.26 


1790 


1.24 


1.59 


2.15 


1.74 


1.41 


1.33 


1.33 


1.35 


1.28 


1.30 


1800 


1.32 


0.92 


1.17 


1.18 


1.29 


1.40 


1.28 


1.26 


1.43 


1.44 


1810 


1.48 


1.54 


1.60 


1.89 


2.02 


1.74 


1.87 


1.41 


1.66 


1.48 


1820 


1.52 


1.47 


1.44 


1.29 


1.22 


1.61 


1.62 


1.61 


1.72 


1.76 


1830 


1.84 


1.96 


2.46 


1.99 


1.23 


1.49 


1.53 


1.34 


1.64 


1.54 


1840 


1.95 


1.59 


1.82 


1.48 


1.32 


2.16 


1.65 


1.73 


1.57 


1.20 


1850 


1.36 


1.49 


1.45 


1.82 


1.67 


2.18 


1.67 


1.48 


1.45 


1.17 


1860 


2.39 


1.87 


1.45 


1.40 


1.79 


1.26 


1.42 


1.28 


1.79 


1.98 


1870 


2.86 


2.24 


2.36 


2.60 


1.59 


2.33 


1.90 


2.01 


2.26 


2.22 


1880 


1.78 


2.08 


1.66 


1.75 


2.24 


2.32 


1.67 


1.50 


1.47 


1.62 


1890 


1.48 


1.70 


1.82 


1.97 


2.18 


1.91 


1.81 


1.71 


1.69 


1.74 


1900 


2.28 


1.65 


1.60 


1.77 


1.48 


1.70 


1.61 


1.62 


1.37 


1.02 


1910 


1.22 


1.03 


1.22 


1.42 


1.50 


1.26 


1.06 


0.84 


0.80 


1.03 


1920 


1.07 


1.12 


0.95 


1.18 


0.57 













156 



CLIMATIC CYCLES AND TKEE-GROWTH 



Big Creek, California (BC), 5 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1700 




• • 




0.80 


0.60 


1.08 


0.58 


0.70 


0.73 


0.60 


1710 


1.12 


1.05 


1.12 


1.00 


1.18 


0.93 


1.18 


1.38 


2.40 


2.10 


1720 


2.22 


1.53 


1.66 


1.89 


1.56 


1.85 


1.97 


1.82 


1.45 


0.96 


1730 


1.84 


2.11 


2.15 


1.59 


1.94 


1.71 


1.95 


1.89 


3.18 


2.60 


1740 


3.56 


3.05 


3.22 


2.94 


3.19 


3.42 


4.08 


3.62 


3.24 


2.84 


1750 


2.86 


2.81 


2.43 


2.18 


2.48 


2.11 


1.81 


1.90 


1.86 


2.41 


1760 


2.62 


2.72 


2.06 


2.27 


1.89 


2.10 


2.68 


1.82 


2.26 


2.87 


1770 


2.62 


3.28 


2.36 


3.13 


2.70 


1.88 


1.63 


1.13 


1.71 


1.70 


1780 


1.96 


2.06 


1.70 


1.32 


2.57 


2.55 


1.84 


1.93 


1.52 


2.39 


1790 


2.71 


2.12 


2.29 


2.22 


1.59 


1.13 


1.68 


2.05 


1.76 


2.17 


1800 


1.98 


2.38 


2.36 


2.20 


2.24 


1.97 


2.18 


2.62 


2.16 


2.04 


1810 


2.95 


2.44 


1.77 


2.47 


2.32 


2.53 


2.45 


2.06 


1.92 


1.92 


1820 


1.79 


1.66 


1.63 


1.77 


1.58 


2.16 


1.89 


1.78 


2.02 


1.23 


1830 


2.28 


2.00 


1.75 


1.91 


1.65 


1.78 


2.25 


1.42 


1.64 


1.68 


1840 


1.84 


1.26 


1.45 


1.22 


0.87 


1.67 


1.22 


1.14 


1.17 


1.06 


1850 


1.39 


1.41 


1.44 


2.00 


1.61 


1.59 


1.78 


1.52 


1.32 


1.54 


1860 


2.03 


1.56 


1.28 


1.13 


0.78 


1.35 


1.29 


1.24 


1.70 


1.55 


1870 


1.54 


1.64 


2.52 


1.62 


1.46 


1.83 


1.46 


1.26 


1.87 


1.19 


1880 


1.08 


1.17 


0.83 


0.80 


1.53 


1.14 


0.98 


1.00 


1.06 


0.99 


1S90 


1.38 


1.27 


1.04 


1.34 


1.36 


1.55 


1.43 


1.70 


1.15 


1.23 


1900 


1.28 


1.52 


0.93 


1.11 


0.99 


1.37 


1.21 


1.42 


1.14 


1.28 


1910 


1.46 


0.93 


0.72 


0.93 


1.38 


1.03 


1.04 


0.98 


1.03 


1.09 



Springville Pines (EP), 8 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1720 


0.70 


0.62 


0.90 


1.18 


0.65 


0.72 


0.78 


0.90 


0.65 


0.51 


1730 


0.68 


0.50 


0.70 


0.85 


0.62 


0.65 


0.70 


0.55 


1.00 


0.68 


1740 


0.62 


0.92 


0.82 


0.62 


0.78 


1.05 


0.70 


0.92 


0.92 


0.85 


1750 


1.12 


0.85 


0.85 


1.00 


0.65 


0.51 


0.65 


0.72 


1.08 


0.85 


1760 


0.78 


1.25 


0.92 


1.15 


1.05 


0.92 


1.33 


1.22 


1.40 


0.73 


1770 


0.92 


1.12 


1.21 


1.52 


1.52 


1.50 


1.29 


0.60 


0.78 


0.92 


1780 


1.01 


0.73 


0.96 


0.51 


0.62 


0.92 


0.94 


0.91 


0.74 


0.89 


1790 


0.97 


1.31 


1.35 


1.12 


1.25 


0.73 


0.64 


0.93 


0.94 


0.84 


1800 


1.08 


1.07 


1.15 


1.51 


1.36 


1.37 


1.16 


1.17 


0.89 


0.94 


1810 


0.92 


1.15 


0.70 


0.97 


0.93 


1.02 


1.18 


0.87 


1.28 


1.20 


1820 


0.90 


1.09 


0.65 


0.64 


0.63 


1.02 


1.24 


0.98 


1.28 


0.94 


1830 


0.98 


1.21 


1.27 


0.87 


0.64 


0.79 


0.84 


0.80 


1.01 


1.11 


1840 


1.22 


0.62 


0.88 


0.67 


0.61 


0.90 


0.54 


0.49 


0.54 


0.67 


1850 


1.04 


1.07 


1.23 


1.37 


1.06 


1.59 


1.14 


1.06 


0.57 


0.64 


1860 


1.03 


0.95 


0.79 


1.02 


0.52 


0.81 


1.05 


0.97 


1.25 


1.43 


1870 


1.07 


1.18 


1.35 


1.04 


0.93 


1.13 


0.86 


0.91 


1.11 


0.98 


1880 


0.66 


0.97 


0.91 


1.02 


1.07 


1.79 


1.42 


1.04 


1.07 


0.80 


1890 


0.74 


0.92 


0.87 


1.08 


1.18 


1.28 


1.02 


1.19 


0.89 


0.85 


1900 


1.04 


0.89 


0.90 


1.16 


0.94 


0.88 


1.01 


1.16 


1.09 


1.32 


1910 


1.14 


0.84 


0.74 


0.78 


0.85 


0.77 


0.91 


0.85 


0.66 


0.71 


1920 


0.73 


0.72 


0.69 


0.88 


0.56 













Mount Wilson, California (W), 8 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1720 












10.40 


11.00 


9.10 


9.10 


5.90 


1730 


6.00 


8.90 


6.30 


8.10 


7.10 


5.90 


6.35 


7.00 


5.80 


6.10 


1740 


6.70 


7.90 


7.75 


6.60 


5.85 


8.95 


7.05 


8.45 


7.60 


8.90 


1750 


4.75 


5.15 


6.80 


4.20 


3.30 


6.10 


4.55 


5.85 


6.25 


5.15 


1760 


6.30 


7.60 


5.85 


7.30 


9.35 


5.85 


8.70 


7.25 


8.55 


6.61 


1770 


7.10 


7.23 


5.52 


6.20 


6.25 


5.62 


5.12 


4.57 


5.40 


5.50 



APPENDIX 



157 



Mount Wilson, California (W), 8 trees — Continued 



A.D. 





1 


2 


3 


4 


S 


6 


7 


8 


9 


1780 


6.13 


7.00 


5.37 


5.30 


7.00 


6.70 


4.30 


5.12 


4.65 


5.22 


1790 


5.32 


4.90 


6.45 


5.97 


4.45 


2.88 


2.77 


4.60 


3.77 


5.47 


1800 


5.60 


5.77 


7.15 


6.12 


8.50 


7.65 


5.85 


4.67 


7.05 


6.05 


1810 


5.75 


6.15 


4.56 


4.72 


4.42 


5.49 


5.34 


4.81 


6.86 


5.40 


1820 


6.25 


5.08 


5.00 


4.11 


3.93 


4.83 


5.83 


5.10 


5.43 


5.16 


1830 


4.86 


4.63 


5.98 


4.26 


3.85 


4.41 


4.00 


4.96 


4.91 


5.26 


1840 


5.71 


3.70 


4.51 


3.16 


3.61 


3.97 


4.13 


4.13 


3.37 


3.80 


1850 


4.55 


4.45 


4.70 


5.06 


4.99 


6.50 


2.79 


2.81 


3.46 


4.82 


1860 


5.26 


4.71 


5.66 


5.26 


3.42 


4.15 


4.67 


4.32 


5.92 


5.75 


1870 


6.21 


5.01 


5.46 


5.49 


5.12 


5.70 


4.86 


4.01 


4.93 


4.42 


1880 


3.05 


4.52 


3.87 


4.31 


4.17 


4.67 


4.042 


4.25 


3.57 


3.48 


1890 


4.89 


5.11 


4.62 


4.63 


4.18 


4.27 


3.85 


3.60 


3.96 


2.77 


1900 


5.22 


4.91 


3.75 


3.89 


3.72 


4.47 


5.18 


4.68 


5.63 


3.51 


1910 


3.38 


3.17 


3.93 


3.85 


3.91 


4.25 


4.45 


4.81 


3.76 


4.47 


1920 


4.45 


5.16 


4.75 


4.90 


3.27 


3.03 











San Bernardino (SB) , 6 trees 



A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1810 




















1.88 


1820 


1.39 


0.90 


1.24 


1.72 


1.38 


2.03 


2.16 


1.81 


1.54 


1.98 


1830 


1.74 


1.54 


1.51 


1.50 


1.02 


1.41 


1.36 


1.19 


1.17 


1.25 


1840 


1.06 


0.77 


0.85 


0.92 


0.98 


1.20 


1.67 


1.56 


1.31 


0.92 


1850 


1.10 


1.27 


1.30 


1.88 


1.22 


1.67 


1.08 


0.94 


1.15 


1.14 


1860 


0.88 


1.02 


0.87 


1.00 


0.82 


0.79 


1.18 


1.16 


1.15 


1.06 


1870 


1.06 


1.23 


1.66 


1.60 


1.77 


1.66 


1.22 


1.09 


1.17- 


0.93 


1880 


0.65 


0.93 


0.73 


0.89 


0.77 


1.03 


0.75 


0.65 


0.73 


0.86 


1890 


0.85 + 


0.97 


0.92 


0.95 


0.98 


1.13 


1.09 


1.11 


1.22 


1.03 


1900 


1.42 


1.41 


1.07 


0.91 


1.03 


0.76 + 


0.88 


0.89- 


0.89 


0.79 


1910 


0.74 


0.71 


0.88 


0.92 


1.03 


0.76 


1.07 


0.86 


0.80 


0.83 


1920 


0.94 


1.11 


























Charleston 


Nevada (CH), 8 trees 








A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1700 


2.70 


1.78 


2.43 


1.03 


2.18 


1.78 


1.73 


1.03 


1.47 


1.40 


1710 


0.95 


1.13 


1.22 


0.82 


1.12 


1.07 


0.61 


0.83 


1.00 


1.08 


1720 


1.72 


1.33 


0.92 


1.84 


1.36 


1.52 


1.94 


1.65 


1.83 


0.61 


1730 


1.54 


1.26 


1.44 


1.41 


1.38 


1.12 


0.63 


1.00 


1.51 


1.05 


1740 


1.19 


1.21 


1.41 


1.69 


1.86 


1.55 


2.23 


2.09 


1.37 


1.53 


1750 


2.00 


1.54 


1.23 


0.77 


0.72 


0.73 


0.99 


1.09 


1.37 


1.73 


1760 


1.78 


2.27 


1.63 


1.34 


1.39 


0.59 


1.63 


1.64 


1.80 


1.26 


1770 


1.39 


1.55 


1.77 


1.35 


2.28 


1.82 


1.90 


1.27 


1.09 


1.19 


1780 


1.60 


1.59 


0.77 


1.10 


1.80 


0.84 


1.25 


1.06 


0.65 


1.04 


1790 


1.02 


1.14 


1.59 


2.10 


1.66 


0.36 


0.64 


1.15 


0.97 


1.52 


1800 


1.10 


1.08 


1.27 


1.12 


1.25 


1.02 


1.46 


0.72 


1.05 


0.56 


1810 


0.69 


1.09 


1.20 


0.51 


0.82 


0.79 


1.06 


1.06 


2.13 


2.43 


1820 


2.59 


2.42 


1.27 


0.93 


1.49 


1.52 


1.92 


1.34 


1.87 


1.32 


1830 


1.57 


1.58 


1.88 


1.55 


1.42 


1.43 


0.65 


1.66 


1.57 


1.90 


1840 


1.59 


0.75 


1.08 


1.21 


1.04 


0.99 


1.32 


0.86 


1.34 


1.17 


1850 


1.29 


1.04 


1.42 


1.76 


1.84 


1.70 


0.78 


0.26 


0.79 


0.88 


1860 


1.03 


1.33 


1.60 


1.35 


0.89 


1.37 


1.90 


1.94 


2.15 


1.66 


1870 


2.18 


1.76 


1.38 


1.66 


2.08 


2.11 


1.88 


1.59 


1.67 


0.95 


1880 


1.02 


1.06 


1.03 


0.92 


0.97 


1.27 


0.87 


1.44 


1.28 


1.46 


1890 


1.49 


1.78 


1.86 


1.86 


2.11 


1.72 


1.13 


1.54 


1.24 


0.53 


1900 


0.77 


1.11 


0.98 


1.07 


1.40 


1.33 


1.69 


1.63 


1.97 


1.83 


1910 


1.62 


1.53 


1.55 


1.59 


1.67 


1.37 


1.63 


1.61 


2.20 


1.74 


1920 


2.05 


2.40 


2.47 


2.60 















158 



CLIMATIC CYCLES AND TREE-GROWTH 









Pine Valley, 


California (PV), 4 trees 








A.D. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


1730 


. > 




.... 








1.65 


1.33 


1.25 


1.02 


1740 


1.33 


i.ii 


6.67 


1.34 


1.29 


6.87 


0.71 


0.43 


0.53 


0.25 


1750 


0.47 


0.52 


0.61 


0.55 


0.88 


0.93 


1.10 


1.69 


3.36 


3.36 


1760 


4.20 


3.67 


2.86 


2.30 


2.32 


1.40 


3.44 


3.60 


3.50 


2.56 


1770 


1.90 


2.93 


2.45 


1.90 


3.14 


2.39 


2.20 


1.56 


1.39 


1.19 


1780 


1.06 


1.49 


0.58 


1.40 


2.19 


1.52 


2.75 


2.82 


1.84 


1.65 


1790 


1.26 


1.07 


0.60 


1.89 


1.86 


1.68 


1.52 


1.33 


1.00 


1.22 


1800 


1.25 


1.46 


2.16 


1.90 


1.50 


1.97 


1.29 


1.21 


1.67 


1.16 


1810 


1.31 


1.65 


1.42 


1.36 


2.28 


2.40 


2.58 


2.57 


2.24 


2.77 


1820 


0.95 


1.30 


0.85 


0.55 


0.62 


1.10 


1.46 


1.16 


2.10 


0.64 


1830 


0.83 


1.32 


1.25 


1.91 


1.23 


1.28 


1.25 


1.28 


1.31 


1.40 


1840 


1.25 


0.81 


1.39 


0.55 


0.65 


0.51 


0.99 


0.85 


1.18 


1.15 


1850 


1.18 


0.90 


1.56 


1.99 


1.09 


1.47 


0.73 


0.63 


0.75 


0.82 


1860 


0.95 


1.09 


1.39 


1.22 


0.88 


1.27 


1.23 


0.92 


1.41 


1.48 


1870 


0.72 


0.91 


1.06 


0.37 


0.64 


0.65 


0.68 


0.49 


1.27 


0.46 


1880 


1.19 


1.16 


0.61 


0.59 


0.90 


1.20 


1.27 


1.29 


2.04 


1.63 


1890 


1.12 


1.52 


1.39 


1.25 


1.07 


0.95 


1.06 


1.27 


1.00 


0.57 


1900 


0.67 


0.84 


0.53 


0.41 


0.21 


0.64 


0.64 


0.59 


0.72 


0.89 


1910 


0.98 


0.92 


0.66 


0.81 


0.69 


0.84 


1.11 


1.18 


1.05 


1.21 


1920 


1.38 


0.93 


1.28 

















BIBLIOGRAPHY 

Abbot, C. G. 1923. Solar radiation. Report of a conference on cycles. Sup. Geog. Rev., 

Vol. XIII, No. 4, October 1923: 669. 

. 1925. The earth and the stars. 

. 1925 2 . Solar variation and forecasting. Smith. Misc. Coll., vol. 77, No. 5, June 20. 

1925. 
. 1925*. Discussion of analysis (of solar radiation). Bull. Am. Met. Soc, vol. 6, No. 

7, July 1925: 99-100. 
. 1926. A new proof of the variability of the sun, based on Mount Wilson observa- 
tions. Mon. Wea. Rev., vol. 54, No. 5, May 1926 : 191-194. 

. 1927. A group of solar changes. Smith. Pub. 2916, April 25, 1927. 

Adams, W. S. 1923. Sunspots and sunspot cycles. Report of a conference on cycles. Geog. 

Rev., vol. 13, No. 4, Special Sup., October 1923: 670-671. 
Allison, Vebnon C. 1923. The growth of stalagmites and stalactites. Jour, of Geology, 

vol. 31, No. 2, February-March 1923: 106-125. 
Alteb, Dinsmobe. 1921. An apparent rainfall period equal to one-ninth of the sunspot 

period. Mon. Wea. Rev., vol. 49, February 1921 : 74-85. 
. 1922. Rainfall period equal to one-ninth the sunspot period. Kan. Univ. Sci. Bull., 

vol. 13, No. 2: 17-99. Abstract in Bull. Amer. Met. Soc, vol. 4, No. 3. 

March 1923: 37-38. 
. 1924. Application of Schuster's periodogram to long rainfall records beginning 

1748. Mon. Wea. Rev., vol. 52, October 1924: 479-488. 
. 1926. Application of Schuster's periodogram to rainfall periods between 2£ and 9 

years. Bull. Amer. Met. Soc, vol. 7, No. 2, February 1926: 22-23. 
. 1926 2 . An examination by means of Schuster's periodogram of rainfall data from 

long records in typical sections of the world. Mon. Wea. Rev., vol. 54, 

February 1926: 44-57. 
. 1926 3 . Criteria of reality in the periodogram. Mon. Wea. Rev., vol. 54, February 

1926: 57-58. 
. 1927. Investigation of rainfall periodicities between 1} and 2\ years by use of 

Schuster's periodogram. Mon. Wea. Rev., vol. 56, February 1927: 60-66. 

. 1927 2 . A study of the possibility of economic value in statistical investigations of 

o rainfall periodicities. Mon. Wea. Rev., vol. 55, March 1927: 110-112. 

Angstbom, A. 1922. Solar constant, sunspots, and solar activity. Astroph. J., vol. 55, 

January 1922:24-29. 
Antevs, Ebnst. 1922. Recession of the last ice sheet in New England. Am. Geog. Soc 

Research series 11, 1922. 
. 1923. Cycles in glacial and postglacial deposits. Report of a conference on cycles. 

Geo. Rev., vol. 13, No. 4, Special Sup., October 1923: 664-665. 
. 1925. The climatologic significance of annual rings in fossil woods. Am. Jour. Sci., 

vol. 9, April 1925: 296-302. 
. 1925 2 . On the pleistocene history of the great basin. Quaternary climates, Car- 
negie Inst. Wash. Pub. 352: 51-114. 
. 1925 3 . The big tree as a climatic measure. Quaternary climates, Carnegie Inst. 

Wash. Pub. 352: 115-153. 
. 1925 4 . Retreat of the last ice-sheet in eastern Canada. Canada Dept. of Mines., 

Geol. Survey Memoir 146, No. 126, Geol. Series. 
Abctowski, H. 1915. The pleionian cycle of climatic fluctuations. Proc 2d Pan-Amer. 

Sci. Cong., Sec. II, vol. 2, 1917: 172. Same, 1916. Amer. Jour. Sci., vol. 42, 

July 1916: 27-33. 
. 1923. Dissimilitude des fluctuations de la frequence des taches observers au N. et 

au S. de l'equateur solaire. Kosmos. (Bull. Soc. Pol. Nat.) Inst. Geophys. 

Univ. Leopol. Com. 2. 
Austin, L. W. 1927. Long-wave radio measurements at the Bureau of Standards in 1926, 

with some comparisons of solar activity and radio phenomena. Proc. Inst. 

Radio Eng., vol. 15, No. 10, 825-836, October 1927. 
. 1927 2 . Radio atmospheric disturbances and solar activity. Proc. Inst. Radio Eng., 

Vol. 15, No. 10, 837-842, October 1927. , 
Balls, W. L. 1919. The existence of daily growth-rings in the cell-wall of cotton hairs. 

Proc Roy. Soc. B, vol. 90, 1919: 542-555. 
. 1921. A simple apparatus for approximate harmonic analysis and for periodicity 

measurements. Proc. Roy. Soc. A, vol. 99, 1921: 283-292. 

159 



160 BLBLIOGHAPHY 

Balls, W. L. 1922. Apparatus for determining the standard deviation mechanically. Proc. 

Rov. Soc A, vol. 101, 1922: 333-341. 
and H. A. Hancock. 1922 1 . Further observations on cell-wall structure as seen in 

cotton hairs. Proc. Roy Soc. B, vol. 93, 1922: 426-440. 
Bates, Carlos G. and A. J. Henry. 1921. Stream flow at Wagon Wheel Gap, Colorado. 

Mon. Wea. Rev., vol. 49, December 1921 : 637-650. 
and Raphael Zon. 1922. Research methods in the study of forest environment. 

U. S. Dept. of Agr. Bull. No. 1059, May 19, 1922. 
Bauer, Franz. 1922. Periodic oscillations of annual temperatures in Germany. Mon. 

Wea. Rev., vol. 50, April 1922: 199-200. 
. 1925. The 11-year period of temperature in the northern hemisphere in relation to 

the 11-year sunspot cycle. Mon. Wea. Rev., vol. 53, May 1925: 204-208. 
. 1925*. The 3 to 3£ year periodic pressure oscillation in the free atmosphere. Mon. 

Wea. Rev., vol. 53, September 1925: 392-394. 
Bauer, Louis A. 1923. Solar and terrestrial correlations. Discussion, report of a con- 
ference on cycles. Sup. Geog. Rev., Vol. XIII, No. 4, October 1923: 

671-672. 
. 1926. Activity of the sun and of atmospheric electricity on land and sea, 1916-1920. 

Ter. Mag., vol. 31, March 1926: 31. 
. 1926 2 . Sunspot and annual variations of atmospheric electricity with special refer- 
ence to the Carnegie observations, 1915-1921. Carnegie Inst. Wash. Pub. 

175 (vol. 5): 361-386. 
and C. R. Duvall. 1925-26. Studies concerning the relation between the activity 

of the sun and of the earth's magnetism, Nos. I and II. Ter. Mag., vol. 30, 

December 1925: 191-213, and vol. 31, March 1926: 37-47. 
Baxter, Frank C. 1927. See Colton, Harold S. 
Beveridge, W. H. 1921. Weather and harvest cycles. Economic Jour., December 1921: 

429-452. 
. 1922. Wheat prices and rainfall in western Europe. Jour. Roy. Statistical Soc. 

(London), Vol. LXXXV, Part III, May 1922: 412-478. 
Bigelow, Frank H. 1922. The vacuum-pyrheliometer and the solar radiation. Sup. No. 3 

to treatises on atmospheres of sun and earth. 
Bjerkness, V., and colleagues. 1910-11. Dynamic meteorology and hydrography. 

Carnegie Inst. Wash. Pub. 88. 

. 1926. Solar hydrodynamics. Astroph. J., vol. 64, September 1926: 93-121. 

Blake, Dean. 1923. Sonora storms. Mon. Wea. Rev., vol. 51, No. 11, 1923: 585-588. 
Blake, M. A. 1922. Peach yellows and little peach outbreaks come in cycles. New Jersey 

Agr., vol. 4, No. 4, April 1922: 1. 
Boak, A. E. R. 1926. Irrigation and population in the Faiyum, the Garden of Egypt. 

Geog. Rev., vol. 16, No. 3, July 1926: 353-364. 
Brooks, C. E. P. 1924. The difference periodogram — a method for the rapid determination 

of short periodicities. Proc. Roy. Soc. A, vol. 105, 1924. 

. 1926. Climate through the ages. 

. 1926*. Sunspots and variations in the levels of the central African lakes. (A review.) 

Geog. Rev., vol. 16, No. 1, January 1926: 142-143. . 
Brooks, C. F. and Frances V. Tripp. 1925. Solar radiation and the atmosphere. Bull. 

Am. Met. Soc. vol. 6. No. 2: 25. 
. 1926. A possible weather and ocean connection. Bull. Am. Met. Soc, vol. 7, No. 3, 

March 1926: 44. 
Bryan, Kirk. 1922. Erosion and sedimentation in the Papago country, Arizona, with a 

sketch of the geology. U. S. Geol. Survey Bull., No. 730 B. Contributions to 

the Geography of the United States, 1922: 19-90. 
. 1925. Date of channel trenching (arroyo cutting) in the arid southwest. Science, 

vol. 42, No. 1607, October 16, 1925: 338-344. 
Burns, George P. 1920. Eccentric growth and the formation of redwood in the main stem 

of conifers. Univ. of Vermont and State Agr. Coll. Vermont Agr. Exp. Sta. 

Bull. No. 219, June 1920. 
Bush, V. 1920. A simple harmonic analyzer. Jour. Am. Inst. Elect. Eng., October 1920: 

903. 
Campbell, Leon. 1926. Maxima and minima of 272 long-period variable stars. Annals 

Ast. Obs. Harvard Coll., vol. 79, 1926: 91. 
Cannon, W. A. 1925. Physiological features of roots, with especial reference to the relation 

of roots to the aeration of soil. Carnegie Inst. Wash. Pub. 368. 
Carpenter, Ford. A. 1924. Notes on the irregularities of ocean currents, Bull. So. Calif. 

Acad. Sci., vol. 20, No. 3, May-June 1924: 101-102. 
Chaney, Ralph W. 1925. A comparative study of the Bridge Creek flora and the modern 

redwood forest. Pub. 349, Carnegie Inst. Wash., 1925: 1-22. 



BIBLIOGRAPHY 161 

Chaney, Ralph W. 1925 2 . The Mascall flora — its distribution and climatic relation. 

Pub. 349, Carnegie Inst. Wash., 1925: 23-48. 
Chirvinsky, P. N. 1923. Mechanism of sunspots. Astr. Nach. 5220, vol. 218: 178-186. 
Chu, Co-Ching. 1926. Climatic pulsations during historic time in China. Geog. Rev., 

vol. 16, No. 2, April 1926: 274-284. 
Clayton. H. H. 1917. Effect of short-period variations of solar radiation on the earth's 

atmosphere. Smith. Pub. 2446. May 1917. 
. 1920. Variation in solar radiation and the weather. Smith. Pub. 2544, January 15, 

1920. 
. 1923. Variations in solar radiation and the weather. Abstract in Bull. Amer. Met. 

Soc, vol. 4, No. 3, March 1923: 33-34. 
. 1923 2 . The use of observations of solar phenomena in weather forecasting in Argen- 
tina. Abstract in Bull. Amer. Met. Soc, vol. 4, No. 3, March 1923: 34-37. 

. 1923 3 . World weather. 

. 1925. Solar radiation and weather, or forecasting weather from observations of the 

sun. Smith Misc. Coll., vol. 77, No. 6, June 20, 1925. 
. 1925 2 . Solar variation and the weather. Bull. Am. Met. Soc, vol. 6, No. 7, July 

1925: 100-105. 
. 1925 3 . Solar variations (and discussion). Mon. Wea. Rev., vol. 53, December 1925: 

522-528. 
. 1926. Solar activity and long-period weather changes. Smith. Inst. Pub. 2875, 

September 30, 1926. 
Clements, F. E. 1920. Plant indicators: the relation of plant communities to processes 

and practice. Pub. 290, Carnegie Inst. Wash. 
. 1921. Drought periods and climatic cycles. Ecology, vol. 2, No. 3, July 1921: 

181-188. 
. 1921 2 . Aeration and air content: the role of oxygen in root activity. Pub. 315, 

Carnegie Inst. Wash. 
. 1923. Nature of the problem of the cycle. Report of a conference on cycles. 

Geog. Rev., vol. 13, No. 4, Special Sup., October 1923: 657-659. 
and J. E. Weaver. 1924. Experimental vegetation: the relation of climaxes to 

climate. Pub. 355, Carnegie Inst. Wash. 
Clottgh, H. W. 1920. An approximate 7-year period in terrestrial weather with solar cor- 
relation. Mon. Wea. Rev., vol. 48 : 593-597. 
. 1921. A statistical comparison of meteorological data with data of random occur- 
rence. Mon. Wea. Rev., vol. 49, March 1921 : 124-132. 
. 1924. A systematically varying period with an average length of 28 months in 

weather and solar phenomena. Mon. Wea. Rev., vol. 52, September 1924: 

421-441. 
. 1925. A statistical analysis of solar radiation data. Mon. Wea. Rev., U. S. Dept. 

Agr., August 1925, vol. 53: 343-348. Abstract: Bull. Am. Met. Soc, 

July 1925: 97-98. 
Colton, Harold S. 1918. The geography of certain ruins near the San Francisco Moun- 
tains, Arizona. Bull. Geog. Soc. Philadelphia, vol. 16, No. 2, April 1918: 

37-60. 
and Frank C. Baxter. 1927. Days in the Painted Desert and the San Francisco 

Mountains. 
Conzatti, Casiano. 1921. El arbol de Santa Maria del Tule, Secretaria de Educacion 

Publica de Mexico, Talleres Graficos de la Nacion: 1921. 
Cortie, Rev. A. L. 1923. Solar and terrestrial magnetic phenomena, 1913-1921. Mon. Not. 

Roy. Ast. Soc, vol. 83, No. 3, January 1923: 204-215. 
De Geer, Gerard. 1926. On the solar curve as dating the Ice Age, the New York moraine, 

and Niagara Falls through the Swedish time-scale. Data 9, Stockholms 

Hogskolas Geokronol Inst. Geografiska Annaler, 1926, H. 4. 
— — — ■. 1927. Late glacial clay varves in Argentina, measured by Dr. Carl Caldenius, dated 

and connected with the solar curve through the Swedish time-scale. Data 

10, Fr. Stockholms Hogskolas Geokronol Inst. Geografiska Annaler, 1927, 

H. 1-2. 
De Ltjry, R. E. 1922. Meteorological and astronomical pulses. Bull. Amer. Met. Soc, 

vol. 3, No. 3, March 1922: 38-39. 
. 1923. Arrival of birds in relation to sunspots. The Auk, vol. 40, No. 3, July 1923: 

414-419. 
. 1925. Sunspots and the weather. Jour. Roy. Ast. Soc. Canada. December 1925: 

293-298. 
de Miffonis, H. 1924. The periodoscope. Astroph. J., vol. 60, September 1924: 133-139. 
Deadhar, D. G. 1925. On atmospheric radio-activity and Indian weather. Proc Roy. 

Soc, Series A, vol. 109, No. A750, October 1, 1925: 280-286. 



162 BIBLIOGRAPHY 

Dorno, C. 1925. Fluctuations in the values of the solar constant. Mon. Wea. Rev., vol. 

53, December 1925: 519-522. 
Douglas, A. W. 1919. Relation of weather and business in regard to rainfall. Chamber 

of Commerce, U. S. A., Special Bull., February 14, 1919. 
■. 1919 2 . Relation of weather and business in regard to temperature. Chamber of 

Commerce, U. S. A., Special Bull., November 7, 1919. 
Douglass, A. E. 1919. Climatic cycles and tree-growth. Carnegie Inst. Wash. Pub. 289, 

Vol. I. 
. 1920. Evidence of climatic effects in the annual rings of trees. Ecology, vol. 1, 

No. 1, January 1920: 24-32. 
. 1921. Dating our prehistoric ruins. Nat. Hist. Amer. Mus., vol. 21, January 1921: 

27. 
. 1921*. Indication of seasonal variation of weather in the growth of rings of trees. 

Jour. Elect, and West. Industry, vol. 46, May 15, 1921: 510. 
. 1922. Some topographic and climatic characters in the annual rings of the yellow 

pines and sequoias of the Southwest. Proc. Amer. Philo. Soc, Vol. LXI, 

No. 2, April 1922: 117. 
. 1922 s . Some aspects of the use of the annual rings of trees in climatic study. Sci. 

Mon., Vol. 15: 5, July 1922. Reprinted, Smith. Report, 1922, Pub. 2731, 

223-239. 
. 1923. Conclusions from tree-ring data. Report of a conference on cycles. Geog. 

Rev., Vol. 13, No. 4, Special Sup., October 1923: 659-661. 
-. 1923*. General methods in the advance of cycle studies. Report of a conference on 

cycles. Sup. to Geog. Rev., Vol. XIII, No. 4, October 1923: 674. 
. 1925. Tree rings and climate. Radio talks on science. Sci. Mon., vol. 21, July 

1925:95-99. 
■• 1925*. Notes on certain biologic cycles apparently related to solar activity. 

(Abstract.) Bull. Am. Met. Soc, August-September 1925: 129. 
. 1927. Solar records in tree growth. Science, Vol. LXV, No. 1679, March 4, 1927: 

220-221. 
Duvall, C. R., and Bauer, Louis A. 1925-26. See Bauer. 
Eddington, A. S. 1926. The internal constitution of the stars. Cambridge University 

Press. 
Ellsworth, R. S. 1924. The giant sequoia. 
Elton, C. S. 1924. Periodic fluctuations in the numbers of animals; their causes and 

effects. Br. Jour. Exp. Biol., Vol. II, October 1924: 119-163. 
Free, E. E. 1911. The movement of soil material by the wind. U. S. Dept. Agr., Bur. of 

Soils, Bull. No. 68. 
Gail, Flotd W. 1921. Factors controlling the distribution of Douglas fir in semiarid 

regions of the northwest. Ecology, vol. 2, No. 4, October 1921: 281-291. 
Galair, Antonio. 1916. Fluctuaciones climatologicas en los tiempos historicos. Proc. 

2d Pan-Amer. Sci. Cong., Sec. 4, vol. 4, 1917: 475-481. 
Grunskt, C. E. 1927. The improbability of rainfall cycles. Mon. Wea. Rev., vol. 55, 

February 1927: 66-69. 
Guild, F. N. 1920. Flagstaffite, a new mineral from Arizona. Amer. Mineralogist, vol. 5, 

No. 10, October 1920: 155-166. 
. 1921. The identity of Flagstaffite and terpin hydrate. Amer. Mineralogist, vol. 

6, No. 9, September 1921. 
Haasis, Ferdinand W. 1921. Relation between soil type and root form of western yellow 

pine seedlings. Ecology, Vol. II, No. 4, October 1921 : 292-303. 
. 1923. Significance of a 255-year age class in an eastern Kentucky forest. Jour, of 

Forestry, vol. 21, No. 7, November 1923. 
Hale, G. E. 1924. Sunspots as magnets and the periodic reversal of their polarity. Nature, 

January 19, 1924. 
. 1925. A test of the electromagnetic theory of the hydrogen vortices surrounding 

sunspots. Proc. Nat. Acad. Sci., Vol. II, 1925: 691. 
and S. B. Nicholson. 1925*. The law of sunspot polarity, Astroph. J., vol. 62, 

November 1925: 270-300. 
. 1926. Some new possibilities in solar research. Sup. to Nature. No. 2957, July 3, 

1926. 

. 1926 2 . Observations with the spectrohelioscope. Nature, September 18, 1926. 

. 1926 3 . Visual observations of the solar atmosphere. Proc. Nat. Acad. Sci., vol. 12, 

1926: 286. 
. 1927. The fields of force in the atmosphere of the sun. Nature, vol. 119, No. 3002, 

May 14, 1927. 
Harris, J. A. 1926. The correlation between sunspot numbers and tree growth. Mon. 

Wea. Rev., vol. 54, January 1926: 13-14. 



BIBLIOGRAPHY 163 

Helland-Hansen, Bjorn, and Fridtjop Nansen. 1920. Temperature variations in the 

north Atlantic Ocean and in the atmosphere. Smith. Misc. Coll. 2537, 

vol. 70, No. 4, 1920. 
Henry, A. J. 1921. Temperature variations in the United States and elsewhere. Mon. 

Wea. Rev., vol. 49, February 1921: 62-70. 
. 1921 2 . Seasonal forecasting of precipitation — Pacific coast. Mon. Wea. Rev., 

vol. 49, April 1921: 213-219. 
and Carlos G. Bates. 1921. Stream flow at Wagon Wheel Gap, Colorado. Mon. 

Wea. Rev., vol. 49, December 1921 : 637-650. 
. 1922. Douglass on climatic cycles and tree growth. Mon. Wea. Rev., vol. 50, 

March 1922: 125-127. 
. 1922 2 . Clements on drought periods and climatic cycles. Mon. Wea. Rev., vol. 50, 

March 1922: 127-131. 
— ■ . 1923. Terrestrial temperatures in the United States and the sunspot cycle. Mon. 

Wea. Rev., vol. 51, May 1923: 243-249. 
. 1926. The Bruckner cycle in the United States. Mon. Wea. Rev., vol. 54, Decem- 
ber 1926: 507. 
Henry, Augustine, and Margaret G. Flood. 1920. The Douglas firs: a botanical and 

silvicultural description of the various species of Pseudotsuga. Proc. Roy. 

Irish Acad., vol. 35, Sec. B, No. 5, May 1920: 67-92. 
Hopmann, J. W. 1923. Meteorological factors and forest fires. (Abstract.) Bull. Am. Met. 

Soc, vol. 4, No. 12, December 1923: 166-169. 
Hoxmark, Guillermo. 1925. Solar radiation and the weekly weather forecast of the 

Argentine Meteorological Service. Smith. Misc. Coll. 2827, vol. 77, No. 7, 

June 20, 1925. 
Humphreys, W. J. 1920. Physics of the air. Pub. Franklin Inst, of Penn. 

. 1925. Climatic control. Sci. Mon., Vol. XX: 449. 

Huntington, Ellsworth. 1915. Solar activity, cyclonic storms, and climatic changes. 

Proc. 2d Pan-Amer. Sci. Cong., Sec. II, vol. 2, 1917: 411-432. 
and S. S. Visher. 1922. Climatic changes, their nature and causes. Yale Univ. 

Press. 
. 1923. Cycles of health. Report of a conference on cycles. Geog. Rev., vol. 13, 

No. 4, Special Sup., October 1923: 662-664. 
— ■ . 1923 2 . Causes of cycles. Report of a conference on cycles. Geog. Rev., vol. 13, 

No. 4, Special Sup., October 1923: 667-669. 
. 1925. Tree growth and climatic interpretations. Quaternary climates. Carnegie 

Inst. Wash. Pub. 352, 155-204. 
Kapteyn, J. C. 1914. Tree growth and meteorological factors. Rec. Trav. Bot. Neerland, 

11:70, 1914. 
Kidder, A. V. 1924. An introduction to the study of southwestern archaeology. Yale 

Univ. Press. 
Kimball, H. H. 1919. Variation in the total and luminous solar radiation with geographical 

position in the United States. Mon. Wea. Rev., vol. 47, November 1919: 

769-793. 
and Herman E. Hobbs. 1923. A new form of thermo-electric recording pyrhelio- 

meter. Bull. Amer. Met. Soc, vol. 4, Nos. 6-7, June-July 1923: 91-92. 
. 1925. Smithsonian solar-constant values. Mon. Wea. Rev., U. S. Dept. of Agr., 

July 1925, No. 53: 303-306. 
Knowlton, F. H. 1919. Evolution of geologic climates. Bull. Geol. Soc. Amer., vol. 30, 

December 31, 1919: 499-566. 
Lemmon, J. G. 1900. Handbook of West-American cone-bearers. 
Livingston, Burton E., and Forrest Shreve. 1921. Distribution of vegetation in the 

United States as related to climatic conditions. Carnegie Inst. Wash. 

Pub. 284. 
Lockyer, Sir Norman, and W. J. S. Lockyer. 1904. The behavior of the short-period 

atmospheric-pressure variation over the earth's surface. Proc. Roy. Soc, 

vol. 73, April 13, 1904: 457-470. 
Losh, H. M. 1925. See Nicholson. S. B. 

MacDougal, D. T. 1921. Growth in trees. Pub. 307, Carnegie Inst. Wash., 1921. 
. 1923. Records of tree-growth. Report of a conference on cycles. Geog. Rev., vol. 

13, No. 4, Special Sup., October 1923: 661-662. 
and Forrest Shreve. 1924. Growth in trees and massive organs of plants. Den- 

drographic measurements — MacDougal. The growth record in trees — 

Shreve. Pub. 350, Carnegie Inst. Wash., May 1924. 
. 1925. Reversible variations in volume, pressure and movements of sap in trees. 

Pub. 365, Carnegie Inst. Wash. 
. 1926. The hydrostatic system of trees. Pub. 373, Carnegie Inst. Wash. 



164 BIBLIOGRAPHY 

Marvin, C. F. 1920. Forecasting the weather on short-period solar variations. Mon. 

Wea. Rev., March 1920: 149-150. 
. 1921. Theory and use of the periodocrite. Mon. Wea. Rev., vol. 49, March 1921: 

115-121. 
. 1923. Solar radiation intensities and terrestrial weather. Mon. Wea. Rev., vol. 

51, April 1923: 186-188. 
. 1923*. Periodicities in weather and climate. (Abstract.) Bull. Am. Met. Soc, vol. 

4, No. 5, May 1923: 66-67. 
. 1923 3 . Concerning normals, secular trends, and climatic changes. Mon. Wea. 

Rev., vol. 51, August 1923: 383-390. 
. 1923*. Characteristics of cycles. Report of a conference on cycles. Geog. Rev., 

vol. 13, No. 4, Special Sup., October 1923: 666-667. 
. 1924. A new principle in the analysis of periodicities. Mon. Wea. Rev., vol. 52, 

February 1924: 85-89. 
. 1924*. Fitting straight lines to data greatly simplified, with applications to sunspot 

epochs. Mon. Wea. Rev., vol. 52, February 1924: 89-91. 
. 1925. On the question of day-to-day fluctuations in the derived values of the solar 

constant. Mon. Wea. Rev., U. S. Dept. of Agr., July 1925, No. 53: 285- 

303. 
. 1925*. Symposium: solar radiation and the weather. (Abstract.) Bull. Am. Met. 

Soc, vol. 6, No. 7, July 1925: 94-96. 
. 1925*. Solar radiation and weather forecasting. Report of Chief of Wea. Bur., U. S. 

Dept. of Agr., November 24, 1925. 
. 1926. The value of pyrheliometric readings alone for investigations on solar radi- 
ation and weather forecasting. Bull. Amer. Met. Soc, vol. 7, No. 2, 

February 1926:21-22. 
. 1927. Measurements of solar radiation and their interpretation. Mon. Wea. Rev., 

vol. 55, February 1927: 49-56. 
. 1927*. The Wolfer sunspot numbers analyzed as frequency distributions. Bull. 

Am. Met. Soc, vol. 8, No. 5, May 1927: 79. 
Maunder, A. S. D. 1923. The sun and sunspots. Hutchinson's splendor of the heavens, 

ed. by Rev. T. E. R. Phillips and Dr. W. H. Steavenson: 110-153. 
Maunder, E. Walter. 1921-22. The prolonged sunspot minimum, 1645-1715. Jour. Br. 

Ast. Assoc, vol. 32, No. 4, 1921-22: 140. 
. 1922. The sun and sunspots, 1820-1920. Mon. Not. Roy. Ast. Soc, vol. 82, No. 9, 

Sup. No. 1, October 1922: 534-543. 
McEwen, George F. 1918. Oceanic circulation and its bearing upon attempts to make 

seasonal weather forecasts. Bull. Scripps Inst. Biol. Res., Univ. of Calif., 

No. 7, November 8, 1918. 
. 1922. Forecasting seasonal rainfall from ocean temperatures. Bull. Am. Met. Soc, 

vol. 3, No. 10, October 1922: 135. 
. 1923. How the Pacific Ocean affects Southern California's climate. Seasonal rain- 
fall for 1923-24 indicated by ocean temperature. Bull. Am. Met. Soc, 

vol. 4, No. 10, October 1923: 142-148. 
. 1924. Forecasting seasonal rainfall from ocean temperatures. Indications for 

the 1924-25 season in Southern California. Bull. Am. Met. Soc, vol. 5, 

No. 10, October 1924: 137-139. 
. 1925. Ocean temperatures and seasonal rainfall in Southern California. Mon. 

Wea. Rev., vol. 53, November 1925: 483-489. 
Meinzer, O. E. 1926. Plants as indicators of ground water. Jour. Wash. Acad. Sci., vol. 

16, No. 21, December 18, 1926. 
Miller, Dayton C. 1916. A 32-element harmonic synthesizer. Jour. Franklin Inst., 

January 1916: 53-81. 
Miller, Eric R. 1920. Some characteristics of the Callendar pyrheliometer. Mon. Wea. 

Rev., June 1920, No. 48: 344-347. 
Moore, Barrington. 1922. Influence of certain soil factors on the growth of tree seedlings 

and wheat. Ecology, vol. 3, No. 1, January 1922: 65-82. 
Moore, H. L. 1914. Economic cycles; their law and cause. 
. 1921. Generating cycles of products and prices. Quart. Jour, of Econ., vol. 35, 

February 1921 : 215-239. 
. 1921*. Generating cycles reflected in a century of prices. Quart. Jour, of Econ., 

vol. 35, August 1921: 503-526. 
. 1921*. The origin of the 8-year generating cycle. Quart. Jour, of Econ., vol. 36. 

November 1921:1-29. 
. 1923. Economic cycles. Report of a conference on cycles. Geo. Rev., vol. 13, 

No. 4, Special Sup., October 1923: 662. 
Morris, Earl H. 1919. The Aztec ruin. Anthropological papers of Amer. Mus. Nat. 

Hist., vol. 26, Part 1. 



BIBLIOGRAPHY 165 

Murphy, R. C. 1926. Oceanic and climatic phenomena along the west coast of South 

America during 1925. The question of periodicity. Geog. Rev., vol. 16, 

No. 1, January 1926: 53-54. 
Nelson, N. C. 1921. Swiss lake-dweller discoveries. Nat. Hist., Vol. XXI, No. 2, 1921: 

172-174. 
Nicholson, S. B., and Edison Pettit. 1922. The application of vacuum thermo-couples to 

problems in astrophysics. Astroph. J., vol. 56, November 1922: 295-317. 
and George E. Hale. 1925. The law of sunspot polarity. Astroph. J., vol. 62, 

November 1925: 270-300. 
and H. M. Losh. 1925 2 . High and low maxima of alternate cycles. Contrib. Mt. 

Wilson Solar Obs. No. 300, Mon. Not., vol. 85, 1925: 467. 
Pearson, G. A. 1918. The relation between spring precipitation and height growth of 

western yellow pine saplings in Arizona. Jour, of Forestry, October 1918: 

677-689. 
. 1923. Natural reproduction of western yellow pine in the Southwest. U. S. Dept. 

of Agr. Bull. No. 1105, April 27, 1923. 

. 1927. Grazing and reforestation. Jour, of Forestry, Vol. XXV, No. 5, May 1927. 

Pettersson, O. 1923. Innere Bewegungen in den zwischenschichten des Meeres und der 

atmosphare. Abstract in Geog. Rev., vol. 15, No. 4, October 1925 : 690-691 . 
Pettit, Edison, and S. B. Nicholson, 1922. The application of vacuum thermo-couples to 

problems in astrophysics. Astroph. J., vol. 56, November 1922: 295-317. 
. 1926. Ultra-violet solar radiation and its variations. Pub. of Ast. Soc. of the 

Pacific, vol. 38, February 1926: 21-27. 
. 1926 2 . Ultra-violet solar radiation and atmospheric ozone. Pop. Ast., vol. 34, 

December 1926: 631. 
.' 1927. Ultra-violet solar radiation. Proc. Nat. Acad. Sci., vol. 13, June 1927: 

380-387. 
Pickard, Greenleaf W. 1927. The correlation of radio reception, solar activity, and 

terrestrial magnetism. Proc. Inst. Radio Eng., vol. 15, No. 2, 83-97, Feb- 
ruary 1927. and vol. 15, No. 9, 749-766, September 1927. 
Pickering, W. H. 1920. The relation of telescopic definition to cold waves. Mon. Wea. 

Rev., September 1920, No. 48: 511. 
. 1920 2 . The relation of prolonged tropical droughts to sunspots. Mon. Wea. Rev., 

1920, No. 48: 589-592. 
Robbins, William J. 1921. Precipitation and the growth of oaks at Columbia, Missouri. 

Univ. of Missouri, Coll. of Agr., Agr. Exp. Sta. Research Bull. No. 44. 
Rowe, Edgar A. 1925. The value of long-range rainfall forecasting to irrigation and 

water-supply projects in Southern California from an engineering stand- 
point. (Abstract.) Bull. Amer. Met. Soc, vol. 6, No. 12, December 1925: 

180. 
Sanford, F. 1926. Comparison of earth-potential and air-potential variations. Bull. 

Terr. Elec. Obs. of Fernando Sanford, vol. 3, July 1926: 14-20. 
. 1927. Summary of observations on earth-potential and air-potential gradients for 

the year 1926, with some theoretical considerations. Bull. Terr. Elec. 

Obs., March 1927. 
Satles, Robert W. 1922. The dilemma of the palseoclimatologists. Amer. Jour, of 

Sci., vol. 3, June 1922: 456-473. 
Schotte, Gunnar. 1922. Summary of the programme of the Swedish State Institute 

of Experimental Forestry for the period 1922-1926. (In Swedish, Ger- 
man, and English). Meddelanden Fran Statens Skogsforsokssanstalt, 

Hafte 19, No. 1. 
Shreve, Forrest. 1914. The r61e of winter temperatures in determining the distribution 

of plants. Amer. Jour, of Bot., vol. 1, No. 4, April 1914: 194-202. 
. 1914 2 . Rainfall as a determinant of soil moisture. Plant World, vol. 17, No. 1, 

January 1914: 9-26. 
. 1917. A map of the vegetation of the United States. Geog. Rev., vol. 3, No. 2, 

February 1917: 119-125. 
. 1917 2 . The physical control of vegetation in rain-forest and desert mountains. 

Plant World, vol. 20, No. 5, May 1917: 135-141. 
. 1917 3 . The density of stand and rate of growth of Arizona yellow pine as influenced 

by climatic conditions (Pinus chihuahuana and arizonica). Jour, of Forestry, 

vol. 15, No. 6, October 1917: 695-707. 
■ . 1919. A comparison of the vegetational features of two desert mountain ranges. 

Plant World, vol. 22, No. 10, October 1919: 291-307. 
. and Burton E. Livingston. 1921. Distribution of vegetation in the United 

States as related to climatic conditions. Pub. 284, Carnegie Inst. Wash. 
. 1922. Conditions indirectly affecting vertical distribution on desert mountains. 

Ecology, vol. 3, No. 4, October 1922: 269-274. 



166 BIBLIOGRAPHY 

Shbeve, Forrest. 1924. Soil temperature as influenced by altitude and slope exposure. 

Ecology, vol. 5, No. 2, April 1924: 128-136. 
Sonderegger, A. L. 1924. Cyclic fluctuations of water-supply. Pacific Engineer, vol. 

2, No. 6, October 1924: 6-16. 
. 1925. A discussion of the water problems of the valley of Southern California. 

Modern Irrigation, vol. 1, No. 1, July 1925: 18, 34-35. 
Spoehr, H. A. 1922. Photosvnthesis and the possible use of solar energy. Jour. Indus. 

and Engin. Chem., vol. 14, No. 12, December 1922: 1142. 
Stenz, Edward. 1925. Sur la theorie de l'actinometre et sur les m^sures de la radiation 

solaire dans les montagnes. Kosmos, T. 50, 1925: 462-479. Reprint, 

Inst. Ge\>phys. Univ. Leopol. Com., 13. 
Stratton, F. J. M. 1924. Astronomical pnysics. Chap. IV, The sun, 25: 53-55. 
Streiff, A. 1926. On the investigation of cycles and the relation of the Bruckner and 

solar cycle. Mon. Wea. Rev., vol. 54, July 1926: 289-296. 

. 1927. Sunspots and rainfall. Mon. Wea. Rev., vol. 55, February 1927: 69-72. 

Swindells, Rev. B. G. 1923. Comparison of sunspot areas and terrestrial magnetic 

horizontal force ranges 1911-21. Mon. Not. Roy. Ast. Soc, vol. 83, No. 3, 

January 1923: 215-217. 
Tchijewskt, A. L. 1924. Physical factors of the historical process. 
Tinglet, F. G. 1923. A proposed system of graphical extrapolation of weather data, with 

possible application to long-range forecasting. (Abstract.) Bull. Am. Met. 

Soc., vol. 4, No. 5, May 1923: 69-70. 
Tripp, Frances V. 1925. Solar climate. Bull. Am. Met. Soc, vol. 6, No. 2, February 

1925: 30. 
and C. F. Brooks. 1925 1 . Solar radiation and the atmosphere. Bull. Am. Met. 

Soc, vol. 6, No. 2: 25. 
Turner, H. H. 1919. On the 15-month periodicity in earthquake phenomena. Mon. 

Not. Roy. Ast. Soc, vol. 79, No. 6, April 1919: 461. 
1919*. On a long period (about 240 years) in Chinese earthquake records. Mon. 

Not. Roy. Ast. Soc, vol. 79, No. 7, May 1919: 531. 
1920. The long-period terms in the growth of trees. Mon. Not. Roy. Ast. Soc, 

Vol. LXXX, No. 9, Sup. No., October 1920: 793-808. 
1920*. Note on the 240-year period in Chinese earthquakes in the fight of Dr. 

Fotheringham 's paper. Mon. Not. Roy. Ast. Soc, Vol. LXXX, No. 6, 

April 1920: 617-620. 

1925. Note on the alteration of the 11-year solar cycle. Mon. Not. Roy. Ast. 
Soc, vol. 85, No. 5, March 1925: 467. 

1926. On a period of approximately 9.2 years in the Greenwich observations of 
magnetic declination and horizontal force. Mon. Not. Roy. Ast. Soc, 
vol. 86, No. 3, January 1926: 108-118. 

1926 1 . On an unsuccessful search for the 9.2-year magnetic period in sunspot 

records, with a new analysis of those records back to 1610. Mon. Not. 

Roy. Ast. Soc, vol. 86, No. 3, January 1926: 119-130. 
Vaughan, T. Watland. 1923. Sediments and climate. Report of a conference on cycles. 

Geog. Rev., vol. 13, No. 4, Special Sup., October 1923: 665. 
Very, Frank W. 1913. A criterion of accuracy in measurements of atmospheric trans- 
mission of solar radiation. Astroph. J., vol. 37, No. 1, January 1913: 31-47. 
Visher, S. S., and Ellsworth Huntington. 1922. Climatic changes, their nature and 

causes. Yale Univ. Press. 
. 1925. The solar-cyclonic hypothesis and the glacial periods. Sci. Mon., Vol. XX, 

1925: 475. 
Weaver, J. E., and F. E. Clements. 1924. Experimental vegetation: the relation of 

climaxes to climate. Pub. 355, Carnegie Inst. Wash. 
West, Frank L. 1920. Long-time temperature prediction. Science, n. s., vol. 52, No. 

1356, December 24, 1926: 611-612. 
Wolfer, A. 1915. Tafeln der sonnenfleckenhaufigkeit fur die Tatig-keitsperiode von 1901 

bis 1914. Meteorologischen Zeitschrift, Heft 5, 1915: 193-195. 
. 1918 etc. Astromische Mitteilungen Nr. CVII to CXIV gegriindet von Dr. Rudolf 

Wolf. 1918-1926. 
. 1921. Die sonnenfleckenhaufigkeit in den Jahren 1902-1920. Jubilaumsnummer 

der Astr. Nachr. 
. 1925. Observed sunspot relative numbers, 1749-1924. Terr. Mag. and Atmos. 

Elec, Vol. XXX, No. 2, June, 1925: 83-86. 
Woolard, E. W. 1925. On the mean variability in random series. Mon. Wea. Rev., vol. 

53, 107-112, 1925. 
Wylie, Charles C. 1927. The solar cycle in temperature and in crops. Pop. Ast., vol. 

35, No. 5, May 1927: 253-256. 




QK 


Douglass, Andrew Ellicott 


745 


Climatic cycles and 


D62 


tree-growth 


v.2 




cop. 2 




Biological 




& Medical 





PLEASE DO NOT REMOVE 
CARDS OR SLIPS FROM THIS POCKET 

UNIVERSITY OF TORONTO LIBRARY 




<4