BULLETIN CHICAGO NATURAL HISTORY MUSEUM

Volume 37, Number 1 January, 1966

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MUSEUM NEWS

COBURN APPOINTMENT SPURS
MUSEUM DEVELOPMENT

A new Department of Planning and Development was
established by the Museum on January 1 . Mr. Robert E.
Coburn has joined the Staff as Development Officer to co-
ordinate various phases of institutional development, includ-
ing public relations, membership, and all other activities
which communicate the Museum's program to the public.
Our experience in recent years has clearly demonstrated that
Chicago Natural History Museum must develop a broader
base of financial support if it is to maintain and heighten its
past distinction. The development department will aid in
defining financial needs and in making them known to the
community.

Mr. Coburn attended Northwestern University and has
spent 43 years in development work. He joined the Com-
munity Fund of Chicago in 1943 as Associate Executive
Director. He has served as Campaign Director of the Cru-
sade of Mercy and the Community Fund campaigns each
year since that time. He retired from the Community
Fund-Crusade of Mercy at the end of December.

Mr. Coburn has been actively associated with one hun-
dred and fifty fund-raising programs which produced over
$300,000,000 for many non-profit educational, health, and
charitable organizations. He has served as President of the
Indiana Society of Chicago, South Shore Country Club, and
Bryn Mawr Community Church Board of Trustees, and as
Director and Chairman of the Executive Committee of the
Chicago Theological Seminary. Mr. Coburn was also one
of the founders of the Chicago Society of Fund-Raising Ex-
ecutives. He lives at 6700 Oglesby Avenue in the South
Shore section of Chicago.

Page 2 JANUARY

NEW BOTANY CURATOR
STUDIES TROPICAL PLANTS \

Dr. William C. Burger has just been appointed Assistant
Curator of Vascular Plants. He will be concerned with the
plants of tropical North America. His special field will be
floristics of Costa Rica.

Dr. Burger was born in New York City where he attended
Columbia College. He served in Germany and France, in
the Army, after graduation. On his return he worked for a
short while at the New York Botanical Garden and then
moved to Cornell University where he began graduate work.
He studied there under the direction of Professor Robert T.
Clausen and received his M.S. degree for a thesis based on a
statistical study of several populations of the Swamp White
Oak, the Bur Oak and their putative hybrids. Dr. Burger
received his doctorate from Washington University in St.
Louis, where he studied at the Missouri Botanical Garden
under Professor Robert E. Woodson, Jr., an outstanding
American systematise A study of several new-world genera
of the mulberry family was the basis of his thesis — and sub-
sequent contribution to the Flora of Panama.

Dr. Burger joined the Agricultural College staff of Haile
Selassie I University at Alemaya in eastern Ethiopia and
worked on a USAID project administered by the University
of Oklahoma. During his four years there he collected ex-
tensively in Ethiopia, especially in the Harar highlands. He
prepared illustrations and text for a manual of the woody
plants of the Harar highlands and for a text on the identifi-
cation of the families of seed plants in Ethiopia.

His recent return from Ethiopia took him through India,
Thailand, Malaysia, and Australia where he investigated the
many varieties of tropical vegetation. He will go to Central
America in January to begin field work in tropical America.
He will be joined by Chief Curator Louis Williams later in
the season.

NATURE PHOTOGRAPHY EXHIBIT

Outstanding nature photographs, selected from thou-
sands of national and international entries, will go on display
at the Museum during the 21st Chicago international
exhibition of nature photography to be held February 4
through February 27.

Animal, plant, landscape and other nature photographs
will be shown in the competitive exhibition, which is spon-
sored jointly by Chicago Natural History Museum and the
Chicago Nature Camera Club.

More than one hundred prints in both black-and-white
and color, and approximately 700 color transparencies will
be exhibited. The color slides will be projected on two Sun-
day afternoons, February 13 and February 20, at 2:30 p.m.
in the Museum's James Simpson Theatre.

tk fter dealing with the types of mountains, and the tools
L\ of the geologist in dealing with theories of mountain
building (see November, 1964, Bulletin) in Part I,
Dr. Woodland turns, in this article, to aspects of the general
structure of the earth as they relate to mountain building.
He examines the crust and the mantle of the earth, the
topography of the ocean floor and the continental crust.

The Crust of the Earth

The field of study called geophysics has provided much in-
formation particularly about the deeper parts of the crust in
orogenic belts and the way it differs from the present day
stable platforms and oceanic crust. Thus, the study of earth-
quakes themselves is beginning to shed light on the nature of
the movements in the crust which produce the quakes, while
the geographical and depth distribution and periodicity of
earthquakes throughout the world provides information on
the relationship of unstable zones to crustal structures. The
velocity of earthquake waves which
varies with depth zones of the earth
also enables us to infer conditions with-
in the earth below the crust, data

data about crustal structure. A concept which receives much
support from these studies is the generally accepted theory of
isostasy. Isostasy holds that the earth's crust acts as if it is in
a floating equilibrium on a very viscous, but nevertheless
yielding, substratum. It is thus analogous to an iceberg float-
ing in the ocean — in general, the higher the land, the thicker
the crust, and therefore the deeper the Moho discontinuity.
That is, high mountains have deep roots and conversely the
depressed crust of ocean basins is just a thin skin.

On the basis of isostasy it would be predicted that an area
of the crust should sink if subjected to a substantial additional
load, and rise again if relieved of that load. In a number of
instances this seems actually to have been the case. Scandi-
navia and the Hudson's Bay region show evidence of a slow
but persistent uplift during the last several thousand years.
This is interpreted as recovery from the depressed levels
caused when they were loaded with tremendously thick ice
sheets during the Ice Age. In the Glacial Epoch also, a

which must be consistent with any ideas

of the mechanism and sources of energy

for mountain building. Small explosive

charges set off in the ocean or on land

produce man-made seismic waves, which

can be received and analyzed to give

data on variations in crustal thickness

and rock density. The base of the crust is now defined by a

change in velocity of seismic waves; this is called the Moho-

rovivic discontinuity (Moho for short). The accumulation of

information on variations of gravity in different parts of the

world also adds to our understanding of the nature of the

deep parts of the crusts and the region below the base of

the crust, called the mantle.

Results from such investigations show that the thickness
of the continental crust averages nearly 25 miles but increases
to 35 miles or more under high mountain ranges. The crust
is composed of granitic type rocks in its upper portion and
somewhat denser, presumed basaltic types below, immedi-
ately above the Moho discontinuity. Oceanic crust, how-
ever, averages less than four miles in thickness, not including
the water depth, and is essentially composed of material sim-
ilar to the basaltic layer of the continental crust.

Measurement of variations in the magnetic field has also
been rewarding in indicating crustal displacements on a large
scale, for example, in the eastern Pacific floor. Another type
of work based on the earth's magnetic field is the determina-
tion of the direction of magnetism which was sealed into the
rocks at the time they were formed. It is believed that this
provides information on the ancient magnetic fields (thus the
name Paleomagnetism) and analyses of these are interpreted by
some earth scientists as showing that the continents have not
always been in the same position relative to the poles or even
to one another. If such movements are accepted, it is neces-
sary to integrate them into any theory of mountain building.

Gravity determinations are, thus, an important source of

mountain building II

by Bertram G. Woodland, Curator, Igneous and Metamorphic Petrology

much larger lake existed on the site of Great Salt Lake. In
the past 16,000 years it has gradually been reduced to its
present size. In response to this decrease of load, there has
been uplift of the crust to a maximum of over 200 feet, as can
be seen in the warped elevated form of the old shoreline
around the lake.

Gravity and seismic studies, however, indicate that a
straight relationship of height of land to crustal thickness is
oversimplified; lateral variations of density occur both within
the crust and below the Moho, in the upper part of the man-
tle. Thus, areas of thin crust can stand relatively high, if
their densities are abnormally low. To illustrate: a three-
inch column of light balsa wood stands as high in the water
as a six-inch column of heavier maple. Anomalous regions
of thin crust are present in a large portion of the western
United States, particularly west of the Colorado plateau, as
well as along the mid-Atlantic undersea mountain range.
Seismic wave studies indicate that the crust and the upper
mantle have unusually low densities in these areas. These
low densities have a direct bearing on the mountain building
process.

The Oceanic Crust

Within the last two decades our knowledge of the ocean
basins has greatly expanded. The ocean floor is now known
to have a very varied relief. Its major feature is a world-
girdling system of mid-oceanic ridges that rise one to two and
a half miles above the average ocean depth of three miles.
These ridges vary in width from a few hundred to 2500 miles.
In many places the summit zone has a median rift valley,

JANUARY Page 3

sometimes 30 miles wide, along which earthquake shocks
originate.

Iceland, which is noted for its active volcanoes, stands on
the Mid-Atlantic ridge. A median rift passes through the
island in the form of a down-faulted zone marked by active
vertical fissures along which the crust is slowly being torn
apart. Other volcanic islands, such as Tristan da Cunha,
also rise from the ridge system. Along the crests of the ridges
the flow of heat from inside the earth is well above the aver-
age for the rest of the ocean floors and continents. In many
places the ridges are offset along transecting faults.

A rifted ridge in the Indian Ocean connects with the Red

occur in Indonesia, which are a continuation of the young
mountain ranges of Malaya, Burma and the Himalayas. The
lavas and ashes emitted by these circum-Pacific volcanoes are
characterized by an interesting type called andesite. The
composition of andesite and its violent manner of eruption
distinguish it from the basaltic lava emitted by the mid-
Pacific volcanoes such as Hawaii. Associated with these is-
land arcs and with the west coast of Central and South Amer-
ica are amazingly deep oceanic trenches, whose depth below
sea level commonly exceeds the height of Everest. The deep-
est sounding ever made, over 36,000 feet, occurred in the
Marianas Trench.

Structural trends of the rocks in oro-
genic belts. Blank areas include
those where there is insufficient data
and also where flat lying strata
cover the deformed rocks of the crust,
such as in Illinois. Greenland is
nearly all under ice. The shaded
areas are the young mountain ranges
formed within the last 100 million
years, mainly during the latter half
of this period.

Sea rift and thence to the Zambesi River, via the great East
African rift valleys. In the current view, these African rift
valleys were produced as the result of tension which stretched
and fractured the crust along existing faults. The resulting
linear troughs formed by the sinking of crustal rocks show
lower than average gravity values. (In the same way, the
crustal rocks of the Arabian peninsula are believed to have
separated from Africa to form the Red Sea; dense rock from
the mantle welled up to form the sea floor which has higher
than average gravity value.) Recent earthquake tremors
originating along the rift valleys, and much active volcanism,
indicate that these stresses continue today.

The East Pacific ridge runs into the Gulf of California and
up into the line of the great San Andreas fault zone, reappear-
ing off the northernmost coast of California. The 1906 San
Francisco earthquake is a result of movement along the
San Andreas Fault.

The Pacific Ocean has a number of other interesting fea-
tures that concern us. It is more or less ringed with geologi-
cally young mountain systems, such as those on the west coast
of the Americas, and also with an almost complete ring of
active volcanoes, the circum-Pacific "ring of fire." Many of
these volcanoes form islands arranged in arcs, such as the
Aleutians, the Kuriles and the Marianas. Other volcanic arcs

Page 4 JANUARY

This circum-Pacific belt is by far the most seismically ac-
tive area in the world. It is significant that earthquake shocks
originate at different depths in various areas of this belt.
Along the line of the trenches, they occur at shallow depths,
down to about 40 miles. Beneath the volcanic islands they
originate between 40 and 1 80 miles below the surface. Deeper
quakes, some more than 430 miles down, occur on the con-
tinental side of the island arcs. Thus, there seems to be an
active zone of slippage around the Pacific, which dips away
from the ocean and under the continents.

It might be mentioned here that studies of circum-Pacific
earthquakes have revealed a puzzling phenomenon. Analy-
sis of waves generated by earthquakes suggests that the crustal
movements responsible are preponderantly of the type where
one block slides along a vertical fault in an essentially hori-
zontal manner. This movement does not fit the structural
and dynamic models favored by many people, which require
relative vertical movement thrusting an upper block up and
over a lower one along an inclined fault zone.

It is noteworthy that there is no trench off the west coast
of the United States, the line of great volcanoes in the Cas-
cade Mountains is inactive, and there is no inclined earth-
quake zone beneath the coast. The earthquakes of the Amer-
ican west are related to other features such as the San Andreas

• Mid-ocean ridges {dotted) and median rifts (thick line). • Dashed lines represent faulted of sets of ridges and fault scarps of the eastern
Pacific. • The thick, dashed line in the central Pacific is a subsided old ridge. • Rift valleys are shown in east Africa, Siberia and Europe.

• Deep sea trenches are shown in solid black. • Lines of stars are Volcanic arcs. • Shaded areas are zones of earthquakes, the darker areas
of more frequent shocks, the lighter of less frequent.

fault, along which the movement of the crust is such as to
move the area to the west of the fault in a northwesterly
direction relative to the area to the east. All these features
of the Pacific are in strong contrast to those of the Atlantic
Ocean, whose surrounding coasts are not seismic, and have
no festoons of volcanic islands, or rims of young mountains.

Another relatively recent discovery is that the ocean floors,
particularly of the Pacific, are dotted with volcanoes which
rise many thousands of feet above the ocean floor, only some
breaking the surface to appear as volcanic islands or atolls.
Many of these submerged volcanoes, or sea mounts, occur in
linear trends with nearby volcanic islands and atolls, both
active and extinct. When the ages of the individual vol-
canoes in a given chain are compared, they show a progres-
sive increase in age in one direction; for example, the Ha-
waiian islands are older toward the northwest. This suggests
that the magma source (responsible for the building of vol-
canoes) has migrated over the years. Because of the distri-
bution of the linear chains relative to the mid-oceanic ridges,
it has recently been suggested that it is not the magma source,
but the crust itself which has migrated, carrying the volca-
noes with it.

Many of the submerged volcanoes have flat tops which
were formed by the planing off of the peaks by wave action.

With the subsequent subsidence of the volcanoes, these flat-
topped occurrences, called guyots are now submerged under
3,000 to 6,000 feet of water. Guyots emphasize that the ocean
floors are not stable but have been subjected to considerable
subsidence and uplift.

Formation of Continental Crust

Closely connected to the problem of mountain building
are questions about the origin of continents and the perma-
nence of oceans. Continental crust is characterized by the
prevalence of low-density "granitic" type rock or sial as it is
called. Originally it was thought that this formed when the
earth passed through a molten stage much like the slag that
floats on molten iron in a furnace. This may have occurred
in the initial period of earth evolution or later, when an orig-
inally cold earth was warmed up as a result of internal reac-
tions, including that produced by radioactive elements such
as uranium.

Nowadays, it is generally held that the earth was never
completely molten and that the crust evolved by chemical
and gravitational differentiation from the mantle as the
earth's internal temperature increased. However, there is
disagreement about the time involved in producing the crust,
and about whether the crust was formed over only certain

JANUARY Page5

parts of the earth's surface (the continents) or over the entire
surface and subsequently concentrated into the present con-
tinents.

Some data have been interpreted as indicating that the
bulk of the sial was differentiated very early in the earth's
history, say at least by 3J^ billion years ago, and that little
has been added since. Other results suggest that the sial has
grown throughout geologic time, primarily by welding of new
material to the margins of the continents. Granitic type
rocks have been produced in recent geologic times which
appear to have been derived by differentiation from the man-
tle (or from basalt which originated in the mantle), thus sup-
porting the idea of continuous growth. However, many other
"granitic" type volcanic and intrusive rocks, particularly
those associated with the orogenic belts, seem rather to have
been derived by melting of pre-existing sial or at least by mix-
ing of such a source with basalt from the mantle.

Assuming that the bulk of the sial was formed early in the
earth's evolution, it has been claimed that it did so on the
sites of the present continents as a result of inhomogeneities
in the mantle; this implies that the oceans and continents
have been permanently in their present position, the conti-
nents ever changing their shape and relief as a consequence
of orogenesis and erosion and changes in sea level. Alterna-
tively, the sial may have formed over the entire earth's sur-
face. Then vast outpourings of basalt along weaker zones
may have caused the foundering and oceanization of large
areas, the sial being squeezed out laterally in the process and
thickening the continents as the oceans grew in size. Con-
centration and thickening of the sial may also have been pro-
duced by the action of slow-moving currents in the mantle
which would sweep the sial together into the zone or zones
where the currents turn downward. Continued action of
such currents is believed to cause continental drift.

Hypotheses that the continents have not always occupied
the same positions relative to each other or to the poles have
been put forward for many years with supporting evidence
based on the distribution of fossils, on past climate indications
(particularly glaciation in the Southern Hemisphere conti-
nents some 250 to 300 million years ago), and on the fit of the
opposite Atlantic coasts. During recent years, studies of
paleomagnetism in rocks have given strong support to the
idea of drift. Drift, of course, is antagonistic to the idea of
permanence of the oceans. It is worth noting that investiga-
tions of the ocean bottoms so far have revealed no sediments
older than about 100 million years, which is a short part of
the total earth's history, while the rocks of the mid-Atlantic
ridge are also relatively young (the oldest tested to date is
20 million years old). We shall return later to the questions
of continental drift, oceanization of continents and the oppo-
site phenomenon, accretion of oceanic crust to the continents,
which are all pertinent to mountain-building theories.

Folded Zones and Crustal Shortening

There are a number of controversies among geologists over
the interpretation of geological evidence about the mechanism
of the mountain-building process. Foremost among these is
the question of lateral compression. The severe folding of orig-

Page6 JANUARY

inally horizontal beds of sediments in orogenic belts, com-
monly accompanied by recrystallization and development of
new structures such as slate and schist, led to the idea that the
forces responsible had acted in a more or less horizontal direc-
tion, producing a lateral compression. This resulted in the
shortening and thickening of the section of the crust affected:
the greater the folding and piling of folds or slices of rock on
top of each other the greater the shortening. Arising out of
such an interpretation, mechanisms to produce lateral com-
pression have been sought. These ideas have dominated
thought on orogenic processes for the last century as the com-
plex nature of the linear folded belts became more and more
known from geologic studies.

However, during the last 30 years the importance of ver-
tical movements has again been stressed (they were prominent
in geological writings over 150 years ago). There can be no
doubt as to the reality of large vertical movements of parts
of the crust. The accumulation of thousands of feet of sedi-
ment, the bottommost beds of which were laid down in shal-
low water as was the sequence to the very top, demands a
considerable sinking of the area to accommodate the deposits
which isostasy by itself cannot explain. For example, taking
a basin with an initial water depth of 500 feet, filling it with
sediment, and allowing for isostatic settling would permit
only the accumulation of about 1200 feet. Sinking would
then cease and the basin would be full of sediment to sea
level. Likewise, the presence in surface rocks of metamorphic
minerals that must have formed at high temperatures and
pressures found only at considerable depths in the crust (e.g.,
5 to 20 miles) indicates the extent of vertical uplift and erosion
that has occurred. Of course, the proponents of lateral com-
pression as the basic cause of orogenic structures recognize
that considerable vertical movement is a necessity to explain
the elevation of mountain ranges as well as many other geo-
logical phenomena. But the tendency is to regard uplift as
a consequence of initial thickening of the crust followed by
isostatic rise, which continues as erosion removes the load
from the top. Implicit in this is the idea that the uplift mainly
follows the folding and thickening of the crust. Geologists
who consider that vertical movement is the primary deforma-
tion mechanism hold that folding and lateral compression
structures are a resultant; in many cases they thus suggest
that uplift precedes folding. We shall take up these aspects
later and discuss how perhaps the two views can be reconciled.

Geosynclines and Oceanic Trenches

Yet another problem relating to the circum-Pacific region
is the question of whether the deep ocean trenches associated
with volcanic island arcs are modern examples of geosynclines
in their early stages, that is, before being filled with sediment.
There used to be strong opinion against their equivalence
based particularly on the fact that the rocks of orogenic belts
were regarded as having been essentially deposited in rela-
tively shallow seas. The geosynclines would then be similar
to areas of sedimentary deposition off the east coast of the
United States and the area off the Gulf Coast where over
40,000 feet of mainly shallow water sediments have accumu-
lated. (It is possible that the lower parts of the sedimentary

***<*£

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The author, Dr. Bertram G. Woodland, at work in the field. This photo shows Dr. Woodland collecting rock samples in central Vermont.
He has traveled extensively in Great Britain, Norway, France, and the United States observing, and collecting samples for later interpretation.
The dark diagonal lines in this photograph are an excellent illustration of folded rock strata.

column were deposited in water of oceanic depths.) How-
ever, in these areas there is no evidence of particular crustal
unrest and volcanism is, of course, absent. Thus there is no
sign that these areas are destined to be future orogenic zones,
although they may.

On the other hand, there is some support for the opposite
view. Deep sea deposits are known, for example, in the
young mountains of Cuba and Timor (Indonesia). Although
previously not thought possible, it is now believed that great
thicknesses of alternating sandy and shaly rock types, char-
acteristic of many complex mountain belts, may have been
deposited in deep water; the sediments that formed them
were released from unstable slopes near to land and were
transported to greater depths in dense sediment-charged bot-
tom currents called turbidity currents. So it is possible that the
geosynclines which later gave rise to mountain systems were,
at least at some stages in their history, deep-water troughs
similar to the modern oceanic trenches. The modern trench,
over 25,000 feet deep, just north of Puerto Rico contains an
estimated 6,000 to 20,000 feet of sediment probably deposited
by turbidity currents. Future uplift of the area could pro-
duce island structures much like Barbados, for example.

Considerations of Time

Before turning our attention to the various hypotheses of
mountain-building mechanisms we must consider one last
aspect — the important one of time. It was recognized many
years ago that the processes involved in mountain building
are very long, taking several hundreds of millions of years
from the inception of a geosyncline to its final deformation
and consolidation as a relatively quiescent part of a continent.
But the paroxysmal orogenic phase was believed to occur
over a few tens of millions of years near the end of the whole
sequence of events and to occur more or less synchronously
in a number of geosynclines in various parts of the earth's

crust. Thus arose the idea of relatively short periods of wide-
spread crustal unrest and mountain building; these periodic
events were called revolutions.

Continued and more detailed study now shows that the
history of even one geosyncline is more complex than previ-
ously believed and that the time span of deposition, volcan-
icity and deformation varied from place to place. Uplift and
folding migrated in time, both along the geosyncline axis
and at right angles to it. Orogenic movement was active
over hundreds of millions of years and individual events were
not world-wide. Events in one geosynclinal complex may
even have overlapped in time those in another complex con-
sidered to belong to a different "revolution." In any one
particular region, however, it is possible to make out a peri-
odicity: deposition, volcanicity, folding, metamorphism, and
uplift are repeated in adjacent zones which migrate in time.

When the crustal history is examined on a broader time
scale (over the last 3 3^ billion years) a crude cyclical arrange-
ment of activity seems to emerge. Ages of crystallization of
mineral components of rocks (established by measurement of
the time necessary for the breakdown of certain radioactive
elements) are assumed to represent periods of metamorphic
recrystallization and consolidation of molten material in the
crust. These events are broadly interpreted as marking peri-
ods of orogenesis. Pertinently dated minerals from all the
continents show ages which cluster in periods centered around
2,600, 2,100, 1,750, 1,400, 1,000, 500, 350, and 100 million
years ago. These data have tended to revive the idea of a
cyclical mechanism controlling the evolution of the crust. It
has also been suggested that between the major periods of
orogenesis a different type of activity can be discerned — the
outpouring of great quantities of basaltic lava on the conti-
nents, possibly related to periods of tension in the crust.

This article will be continued in subsequent issues of the BULLETIN.

JANUARY Page 7

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CHARLES HAMILTON SEEVERS
1907-1965

Prof. Charles Hamilton
Seevers, Research Associate
in the Division of Insects,
Chicago Natural History
Museum, and Chairman of
the Department of Biology
of Roosevelt University,
died on December 12, fol-
lowing a brief illness. He
was an internationally rec-
ognized authority on the
classification, biology, and
evolution of the Staphylini-
dae or rove beetles, whose
more than 30,000 described species constitute one of the larg-
est families of living things.

Prof: Seevers was born inTopeka, Kansas, April 19, 1907.
He received his bachelor's degree in chemistry from Wash-
burn College, Kansas, in 1928, and his doctorate in Zoology
from the University of Chicago in 1932. He was an instructor
at the Northwestern Missouri State Teachers College in 1933.
In 1934, he was appointed Associate Professor, and later,
Professor and Chairman of the Department of Zoology of
Central Y.M.C.A. College, Chicago, where he remained un-
til 1945. In that year he became Chairman of the Depart-
ment of Biology of Roosevelt University, a school he helped
establish.

Although he did his doctoral research in experimental
embryology, he later turned to the study of the rove beetles
that live with termites. One of his two major monographs,
published by the Museum, deals with the classification and
evolution of these species, the other with those that are guests
of army and driver ants. A third large monograph, revising
the classification of 200 North American genera of one sub-
family, was brought to a conclusion shortly before his death.
In recognition of his outstanding research, he was ap-
pointed a Research Associate by Chicago Natural History
Museum in 1943. He was later elected a Contributor, for
his gift to the Museum of his valuable personal collection.

Prof. Seevers made several collecting trips to Mexico and
one to Colombia. He also made two extended trips to Europe
to study type-specimens, and on one of these he made an in-
ventory of the Knirsch and Brancsik collections of beetles,
which were later purchased by the Museum.

As a teacher, Prof. Seevers was outstanding. The lucidity
and currency of his lectures in such diverse fields as embryol-
ogy, genetics, parasitology, histology, and comparative anat-
omy will long be remembered by his thousands of students,
many of them now doctors, dentists, and biologists.

Prof. Seevers is survived by his widow, Frances B. Seevers,
Curator of the Biology Department at Roosevelt University,
and by his only brother, Dr. Maurice H. Seevers, Chairman
of the Department of Pharmacology at the University of
Michigan Medical School.

Page 8 JANUARY

New Grants to Anthropology

National science foundation has awarded the Depart-
ment of Anthropology of the Museum two grants: (1) for
the support of research entitled "Evolution of Social Organi-
zation in Prehistoric Arizona" for a period of two years; and
(2) for support of an "Undergraduate Research Participation
Program" for 1966. The latter grant will be used to provide
increased opportunities for the scholarly development of eight
outstanding undergraduates. Both grants will be under the
direction of Dr. Paul S. Martin, Chief Curator Emeritus,
Department of Anthropology.

The grant for archaeological research in Arizona is the
fifth one to be awarded the Museum; and the grant for train-
ing undergraduate students is the second one.

Dr. Martin's undergraduate program, typical of a num-
ber of new Museum programs in education, acquaints pros-
pective students in archaeology with theoretical and practical
field work during the summer digs at the Museum's Field
Station in Vernon, Arizona. The result, it is hoped, will be
a clearer, more rounded view of archaeological anthropology
for the undergraduate planning to make this field his life's
work.

COVER: Mount Kangchenjunga on the Nepal-Sikkim bor-
der, the third highest mountain in the world (28,146 feet).
This photograph was made from Darjeeling, India, some
50 miles away, by John Moyerof the Museum staff, while
he was serving as a United States Consul in India.

CHICAGO NATURAL HISTORY MUSEUM

Founded by Marshall Field, 1893

Roosevelt Road and Lake Shore Drive Chicago, Illinois 60605

Telephone: 922-9410

THE BOARD OF TRUSTEES
Lester Armour
Wm. McCormick Blair
Bowen Blair

Walter J. Cummings
Joseph N. Field
Clifford C. Gregg
Samuel Insull, Jr.

Henry P. Isham
William V. Kahler
Hughston M. McBain
J. Roseoe Miller
William H. Mitchell
James L. Palmer
John T. Pirie, Jr.

John Shedd Reed
John G. Searle
John M. Simpson
Edward Byron Smith
Louis Ware
J. Howard Wood

OFFICERS
James L. Palmer, President

Clifford C. Gregg, First Vice-President

Joseph N. Field, Second Vice-President
Bowen Blair, Third Vice-President

Edward Byron Smith, Treasurer and Assistant Secretary
E. Leland Webber, Secretary

DIRECTOR OF THE MUSEUM
E. Leland Webber

CHIEF CURATORS
Donald Collier, Department of Anthropology

Louis O. Williams, Department of Botany

Rainer Zangerl, Department o( Geology

Austin L. Rand, Department of Zoology

THE BULLETIN

Edward G. Nash, Managing Editor

Kathleen Wolff, Associate Editor

BULLETIN CHICAGO NATURAL HISTORY MUSEUM

Volume 37, Number 2 February, 1966

^-^fc

NSF Aids New Programs

MUSEUM TEACHING ARM
PLANS SUMMER COURSES

The Raymond Foundation, one of the Museum's educa-
tional divisions, will offer this summer two six-week programs :
a course in anthropology for high-ability high school students;
and an institute in geology for elementary teachers and super-
visors. Applications for both courses are now being accepted.

Supported by two recent grants from the National Science
Foundation, the courses are representative of new Museum
efforts to fill specific educational needs.

Training in anthropology is not offered in high schools of
the Chicago area. The Museum course, which will be held
from June 27 to August 5, will provide high school students
with an intensive introduction to the study of man. It will
explore the scope of anthropology, the evolution of man, and
the rise of civilizations in both the Old and New Worlds.
Lectures by outstanding authorities, seminars, workshops,
and a week-long dig on a local archaeological site are planned
to give the students a sound foundation in anthropology and
an opportunity to test a possible career interest in the science.

Students from Chicago area public and private high
schools who have completed the 10th or 11th grade by June
are eligible. Selection will be based on academic achieve-
ment, recommendation of teachers, and personal interviews.
Application forms are available by writing Miss Miram
Wood, Chief of the Raymond Foundation, at the Museum.

The program is under the direction of Miss Wood; it was
planned and will be conducted by Miss Harriet Smith and
Miss Edith Fleming, lecturers in anthropology in the Ray-
mond Foundation.

In recent years, geology has been introduced into many
elementary schools. A good number of the grade school
teachers, however, have had little or no training in the sub-
ject. To meet this need, the Museum is offering an institute
in geology for elementary teachers and supervisors in Chicago
and suburban public and private schools. The institute,
which is under the direction of Mr. Ernest Roscoe, lecturer
in geology in the Raymond Foundation, will run from June 27
to August 5.

The program will deal with the fundamental concepts and
principles of physical and historical geology, with emphasis
on the geology of the Chicago area, and will include work on
mineral, rock and fossil identification, lectures and research
work in the laboratory and library. Several full-day field
trips are planned to enable the participants to study local
geology first hand and to apply basic principles in the field.
The field trips will be led by Mr. Harry Changnon, Curator
of Exhibits, Department of Geology.

Applicants for the geology institute must have primary
assignments to grades 4, 5 or 6 and a minimum of three years'
teaching and/or supervisory experience. Those interested in
the program may obtain applications by writing Mr. Roscoe.

March 31 is the deadline for applicants in the geology
institute, March 25 for the anthropology course.

Page 2 FEBRUARY

Slime eels — taken in trap at 4500 meters

Pinecone fish — named for its thick, spiny, bony scales

Examining gills of dolphin fish for parasites

Butterfly fish — an undescribed species from San Felix

A VOYAGE of the ANTON BRUUN

Loren Woods, Curator of Fishes, reports on a research trip

The waters from Panama to southern Chile, from the coast
to the islands several hundred miles out at sea, are greatly
in need of thorough biological exploration. Not that this
region has been completely neglected. The Beagle, with
Charles Darwin aboard, stopped in Chile and Peru and col-
lected shore fishes in the 1830's. Ninety years ago the Chal-
lenger, equipped with trawls and dredges for bottom collect-
ing, visited the Juan Fernandez Islands and fished the deep
waters between these islands and mainland Chile. Several
recent cruises have studied physical oceanography.

To this corner of the Pacific has come the Anton Bruun, the
National Science Foundation research ship, formerly the presi-
dential yacht Williamsburg. After two years exploring the
Indian Ocean, the Anton Bruun is being used to carry on bio-
logical and oceanographic research in the southeastern Pa-
cific. The scientific staff, as in the Indian Ocean Expedition
(see Bulletin, July 1964), is composed of scientists from many
institutions and several countries. I participated in a cruise
in November and December of last year; on board were sci-
entists and students from Scripps Institution of Oceanog-
raphy, University of California at Los Angeles, Cape Haze
Marine Laboratory, Smithsonian Oceanographic Sorting
Center and the Marine Institute of Peru.

The cool Peru Current, flowing northward just off the
coasts of Chile and Peru until it is deflected westward to the
Galapagos Islands, dominates the southeastern Pacific. The
volume of water in the current, which is also called Humboldt
Current, is not very great but there is considerable upwelling
of colder deep water, which brings nutrient materials to the
surface and produces a varied and abundant marine life.

These favorable conditions have made possible the famous
guano industries of Chile and Peru. More recently, by elim-
inating the middleman, and catching the fish before the birds
do, the Peruvian fish fertilizer industry has become the largest
in the world.

Along the western coast of South America, the continental
shelf of shallow water is very narrow, and fifty to a hundred
miles off the coast it plunges into the Peru-Chile Trench with
its depths of more than 20,000 feet. West of the trench, off
central Peru, is a great plateau 12,000-14,000 feet deep. To
the south of the plateau are broken ranges of submerged
mountains (Nazca Ridge). The valleys of these mountains
are at 14,000 feet or so, but many of the peaks reach to within
one or two thousand feet of the surface. Still further south
four peaks actually break the surface, rising as enormous vol-
canic cones from the great depths to more than 6,500 feet
above sea level. These are San Ambrosio, 1,570 feet high and
San Felix, 630 feet high, 500 miles off the mainland, and the
two Juan Fernandez Islands, Mas a Tierra, 3,040 feet, 350
miles off Chile and Mas AJuera, 6,562 feet, 430 miles out.

The objective of this particular cruise, one of a number
the ship will make as the project goes on, was to collect speci-
mens of plants and animals, particularly fish life, at all levels
from tidepools to the deepest parts of the Peru-Chile trench,
using different kinds of nets, traps, setlines and diving gear
for the various levels.

At our starting port, Callao, Peru, there was a delay of
two days because the deep set lines, air freighted from the
States, had not arrived. We spent the time shore-collecting
at San Lorenzo Island, about five miles off Callao Harbor.

FEBRUARY Page 3

Here were steep sandy beaches separated by rocky head-
lands. Collecting was difficult because the water was rough,
murky, and cold (60°). The area was rich in kelp and other
algae, and the rocks were covered by sea cucumbers and star-
fishes. Fishes were rather few in species but there were many
blennies, sea basses, and demoiselles. Surprisingly, no sharks
were seen or collected either here or anywhere else though we
constantly watched for them and fished for them at night.

With the arrival of the deep set lines, we set out from
Callao. The first ten days we fished with midwater trawls,

Route

of the

ANTON

BRUUN

bottom trawls and deep set lines and traps on the continental
shelf, across the Peru Trench and about 300 miles farther west
over the oceanic plateau. The remaining time we worked
southwest from Callao to San Felix Island and the Juan Fer-
nandez Islands. At these islands fishes and invertebrates were
collected with otter trawls, poison, handlines and a light at
night. Midwater and bottom trawling continued in the deep
waters east of Juan Fernandez. We ended the cruise at Val-
paraiso, Chile.

Deep ocean trawling, either in midwater or on the bottom
is a time-consuming operation. The cable must be paid out
and hauled back slowly. Bottom trawling was usually done
during the day and midwater trawling at night. In the great
depths it is always dark on the bottom. Anyway, the animals
stay there regardless of the surface light. In midwaters the
animals migrate toward the surface at night concentrating in
a broad layer. Our objective was to put our net in, or at least
through, this layer and sample the concentration. The net
would be lowered about 5-600 feet at a time and dragged

15-30 minutes at each depth until it had gone down 6-10,000
feet. The net would then be hauled back to within 1,000-
2,000 feet of the surface and the process repeated. Such a
haul generally took from 8 o'clock at night until 4 or 5 the
next morning.

A night's work produced from one to 5 gallons of speci-
mens. There would be many kinds of jellyfishes and a vari-
ety of shrimps ranging from tiny transparent larvae to 6-
inch-long bright red specimens. The fishes most often taken
were lantern fishes, with rows of luminous spots along their
sides; deep-bodied, silvery hatchet fishes; very slender, elon-
gate snipe eels; and viper fish with slender, curved teeth as
long as their jaws. Every haul brought something not caught
before, often species we could not find in the literature, so
they were identified only to family in our records.

The specimens were transferred from the net into deep
trays and sorted, photographed and preserved immediately.
Usually the ship was rolling and tossing so our problem was
to get them swiftly and safely into covered containers before
they were spilled over the deck.

While the all-night trawling operation was proceeding,
the deep set line and trap were fishing on the bottom. This
apparatus consisted of a weighted buoy and trap and a line
with 50-100 baited hooks on leaders. This gear was put over
early in the evening and would sink to the bottom and lie
there all night. By next morning a 12-hour fuse would have
burned through, releasing the weight and allowing the line
and trap to rise to the surface. Then the buoy could be lo-
cated on the radar screen. Since the buoys were only 10 feet
above the water, radar didn't help much if the waves were
higher than 10 feet, which was frequent, but we could usually
sight the buoy since it was painted bright red. If there were
any fishes floating on the hooks, the gathering birds showed us
the location.

A standard set of hydrographic data was collected at each
station where the nets were to be hauled. Water samples
were collected at intervals to the bottom and temperatures
noted. Each sample was chemically analyzed and the amount
of plankton measured. This work was done by three ship
staff technicians who also helped with handling of the fishing
gear. The Peruvian scientists were particularly interested in
surface plankton and so the ship was stopped every four hours
wherever we cruised so a plankton sample could be collected.

When we reached San Felix Island, the emphasis was
shifted to inshore collecting. San Felix is only 1 }/% miles long,
and is very barren black cinder lava and weathered yellow
sandy clay. Because of its distance from the mainland, 500
miles, and difficult anchorage, no fish collections had ever
been made here. We spent several days collecting in the
tidepools and open shallow sea-caves to depths of 110 feet,
using scuba gear and poison. Fishes were abundant but, as
at Callao, the variety was not great. While the diving party
was off in small boats, the crew fished with handlines in the
deeper waters of the anchorage.

Some diving was done at night to collect pine-cone fishes.
This species was previously known from only one dried speci-
men, so several were kept alive in aquaria and observations
made on their behavior. (Continued on page 11)

Page 4 FEBRUARY

Spring
Lecture Series

This year's Spring Lecture Series offers film studies on the people, the
history, and the natural riches of many areas around the world. The nine
films, all in color and all with personal commentary by well-known lecturers,
are presented by the Museum as the 125th Series of Illustrated Free Lectures.
They will be held in the James Simpson Theatre of Chicago Natural History
Museum at 2:30 p.m. on successive Saturday afternoons from March 5 through
April 30. Reserved seats for Museum members will be held until 2 :25.

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Paris

March 5, Paris

Paris has for centuries enjoyed an aura of romance and fan-
tasy. It holds charm for people of many interests, from haute
couture to medieval history, from Left Bank bistros to the ele-
gant Table du Roy. Veteran film maker Eric Pavel presents
the storied city with authority and style, shows its complexity
and variety, its seamy side as well as its grandeur.

March 12, Mexico's California

A beautifully photographed study of the flora and fauna of
Lower California and the tropical islands along its shores.
Laurel Reynolds and Mindy Willis, the film-makers, also pre-
sent some of the historical landmarks of this part of Mexico,
where ancient customs still flourish beside the ways of today.

March 19, Tales of the Mid-Pacific

The capture of a whale and its subsequent performance at
Sea Life Park — tracking a 65-mile-wide whirlpool — a descent
into a volcanic crater; these are some of the highlights of this
Len Suttman film. He uses Hawaii, with its "crossroads"
culture of east and west, as the base from which to explore
life in the surrounding seas.

March 26, Egypt— The Golden Land

Animated maps, an innovation by Clifford J. Kamen, trace
the route followed in his film. Starting at the mouth of the
Nile, beautifully composed film sequences show the ancient
and modern sights of Alexandria, Cairo, the Sahara, Luxor,
Aswan, the Suez Canal, and Mount Sinai. Remarkable shots
inside the Pyramids distinguish this movie.

April 2, South Viet Nam

Kenneth Armstrong presents in-depth observations on the
people of Viet Nam. With the understanding gained in
many months of reporting in Viet Namese cities, in rural
areas, and in combat areas, he is able to show the bearing of
history, custom and religion on the present struggle in this
crucial area.

/

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Arctic

Puerto Rico

April 9, Australia

A real life study of the people "down under," and the rela-
tively untouched natural wealth of their continent. Presented
by Charles Forbes Taylor, longtime lecturer on platforms all
over the world.

April 16, High Arctic

An intimate documentary on the life of the northernmost
Eskimos, by noted explorer Lewis Cotlow. Shows how their
survival in an almost Ice-Age environment depends on their
ingenious use of the few natural resources available to them.

April 23, Timeless Turkey

Turkey in the sense of a bridge — between the East and the
West, and between its historical-legendary past and its future
of progress in agriculture, industry and education. Com-
mentary by Arthur Dewey, experienced lecturer-film-maker.

April SO, Puerto Rico

Fran William Hall conducts a tour with the help of native
Puerto Ricans; from the fern-tree forests to the residence of
the lady-mayor of San Juan, from a steel band practice ses-
sion to Pablo Casals in rehearsal, the island is presented
through the eyes of its inhabitants.

Egypt
FEBRUARY Page 5

recent acquisitions-anthropology. ..

PRE-COLUMBIAN POTTERY FIGURES

this pottery figure from the
Nicoya Peninsula of Costa Rica
was presented to the Museum
as the gift of Raymond Wielgufl
Product Models. Inc. It stands
nine inches high, is made of red-
dish-buff pottery painted with
designs in red, black and gray
and represents a female figure.
A polychrome style of pot-
tery flourished for 1 300 years on
the northwest coast of Costa
Rica in the province of Guana-
caste, including the Nicoya Pen-
insula, and in adjacent Nica-
ragua. Recent archaeological
work has distinguished three periods in Nicoya Polychrome
pottery: early, dating from a.d. 200 to a.d. 800; middle,
a.d. 800 to 1175: and late, from 1175 to 1560. This figurine
falls in the style of Early Polychrome B and thus dates from
a.d. 600 to 800. The development of the Early Polychrome
style seems to have been influenced by the Classic Mayas.
The nature of this relationship will not be understood until
more is known about the archaeology of the area lying be-
tween northwestern Costa Rica and the eastern Maya frontier
in Honduras and Salvador.

the colima style of ceramic
sculpture flourished on the
west coast of Mexico from
about 100 B.C. to a.d. 600.
Colima-style figures are nat-
uralistic, refined and elegant.
They have highly burnished
red, brown or black surfaces
without textural or painted
elaboration. The men and
women have strong, tranquil
faces and a peasant solidity.
This new acquisition
shows a seated man holding
a large pot on his lap. He is naked save for a breech cloth,
ornaments on his upper arms, and a headdress consisting of a
fillet around the head held by a strap under the chin. The
hair is long and hangs down his back. This specimen, made
of red pottery with incised design is 14l/£ inches high, and
dates from about a.d. 600. It is the gift of Julian R. Goldsmith.
The Colima sculptors also depicted mammals, birds, rep-
tiles, fish and shellfish. Their favorite animal was the dog,
of which they made a great variety of hollow effigies. Dogs
were raised by the ancient Mexicans both for food and sacri-
ficial offerings. It is not clear whether the Colima clay dogs
were placed in tombs as food offerings or to represent dogs
sacrified at the funerals to assist their masters in the difficult
journey to the land of the dead.

Many other fine Colima pieces, including three dogs, are
on display in Hall 8 (Indians of Mexico and Central America).

Page 6 FEBRUARY

mc

When one considers various theories of mountain building
that have been proposed, one discerns a fundamental
problem: — is it necessary to consider all the major features of
the earth now known and so to strive after one mechanism
that fits them all? Or should one try to elaborate a process
that appears to explain mountain building without conflict-
ing with other features, thus leaving the explanation of these
features to other processes? A similar dilemma concerns the
source of the energy that drives the one or more mechanisms,
although as will be noted at the end, the energy problem
seems a little more circumscribed than the problem of the
possible mechanisms of mountain building.

The Contraction Theory

The gradual accumulation of knowledge about the distri-
bution of folded strata, particularly of the linear belts of com-

The wrinkled skin of a dried (shrunk) apple compares
with mountain ranges (wrinkles) on a contracting earth.

by Bertram G. Woodland, Curator, Igneous and Metamorphic Petrology

jntain building III

plex folds, led to the idea of horizontal compression in the
crust as the operating force which caused the crumpling. A
French geologist, Elie de Beaumont, in 1829 proposed that
the compression originated through the contraction of the
earth as it cooled. The hypothesis received much support
about the turn of the century when it was recognized that in
the Alps large slices of the earth's crust had been folded, dis-
located, and thrust over others for distances up to tens of
miles. Such overthrusting of masses thousands of feet thick
was interpreted as proof of considerable crustal shortening by
compression as a result of contraction. The fact that the
folded zones occurred in restricted parts of the crust was ex-
plained by the crust's heterogeneity, certain sections behav-
ing more plastically than the rest, which acted as rigid blocks.
The geosynclines, in which large thicknesses of sediment accu-
mulated prior to their conversion to folded mountain belts,

were also believed to have formed as large crustal down-
buckles produced by lateral compressive forces in the crust.
Contraction of the earth by cooling was an attractive idea
as the earth was believed to have originated by condensation
from hot nebular gases. It would have passed through a
completely molten stage and on further cooling its mantle
would have gradually solidified. An earthquake wave dis-
continuity at a depth of about 1,800 miles has been inter-
preted as the boundary between the solid mantle and the still
liquid core of iron-nickel which is supposed to have settled
inward under the influence of gravity. The crust formed as
an early crystallized layer, likened to the slag floating on the
iron in a blast furnace. The zone of cooling in the upper
mantle is a region of contraction, while above this layer the
already cooled crust and uppermost mantle are under com-
pressional forces as they adjust to a smaller area.

Vertical section of the crust and upper mantle at right angles to an orogenic belt according to the contraction theory.

FEBRUARY Page 7

One version of the mechanism of orogenesis suggests that
the crust is pulled down to form a trough which becomes a
geosyncline and is filled with sediment. Further compression
of the crust leads to deformation of the thick deposits, meta-
morphism of the deep roots, production of magma and intru-
sion of granitic material; concomitant uplift is produced by the
compressional thickening of the crust and isostatic response.

Another version attempts to relate the operation of the
forces arising from contraction more directly to the large scale
structures of the present active belts and their associated vol-
canic and seismic activity. Thus, continental margins with
their thick load of sediment constitute a 'weak' zone which
serves to focus rupture in both the contracting and the crustal
compressional zones. Failure by faulting would take place
along inclined planes which intersect the earth's surface as
arcs. The inclined fault planes are equated with the inclined
zones of earthquake origin which dip from the oceanic
trenches toward and under the neighboring continents. Ar-
cuate volcanic islands are formed by magma produced along
the fault zone. The fault zone within the zone of compression
is manifested by thrusting, which eventually affects the folded
and altered sediments of the trough. Uplift of these trans-
forms the trough into a geanticline, a new deep trough forms
on the oceanward side, and the process is repeated.

There are a number of strong objections to the contraction
theory. Today, the evolution of the earth from a hot gas
cloud through a completely molten stage is not considered
likely. Instead, it is believed the earth evolved by the agglom-
eration of many small cold bodies that formed in an orbit
around the sun. The earth would gradually become heated,
however, as a consequence of the great pressures developed
internally and also from the energy released by the break-
down of radioactive elements. There is dispute about how
much heat would be developed. Some hold that it would
have been sufficient to largely melt the earth at an early stage
and so aid the formation of the metallic core and sialic crust.
Solidification of the mantle and further cooling would have
ensued, allowing the application of the contraction hypothesis
for mountain building as outlined above. Others consider
that the rise in temperature has never been enough to bring
about anything like complete melting and, further, that the
earth may still be warming up rather than cooling. These
different interpretations arise because, as yet, we do not have
enough criteria on which to establish a generally acceptable
set of calculations of the thermal history of the earth.

There are three modifications of the contraction theory
that do not depend on cooling as the underlying cause. One
suggests that the production of magma by partial melting of
the upper mantle and its extrusion to the surface would re-
sult in contraction of the mantle. The contraction would
provide the forces for mountain building as described. Addi-
tionally, the magma produced throughout geologic time
would form the basaltic crust of the oceans and the sialic con-
tinental crust. The magma for the latter would originate at
greater depths and be extruded at the margins of the conti-
nents (volcanic island arcs); the continents thus grow in size
marginally. There is no evidence that volcanism is quantita-
tively adequate to produce contractional forces in the mantle

Page 8 FEBRUARY

CRUST

Base Is Moho
Discont inui t y

Section of the earth showing internal structure.

and, as mentioned earlier, calculations suggest it is also inade-
quate to explain continental accretion in the time available.

The other variants of the contraction theory postulate that
the core of the earth has been increasing in size throughout
the earth's history. Generally, it is considered that the core
is composed of iron-nickel; this is in accord with the overall
density of the earth and with the iron-nickel meteorites that
are presumed to have formed deep within a now fragmented
planet. In contrast to the mantle, the greater part of the core
behaves as a liquid with respect to the transmission of seismic
waves. (A smaller inner core with a radius of about 750 miles
is believed to be solid.)

Some earth scientists believe the core has grown continu-
ously by gravitative settling of iron after radioactive heating
had warmed the mantle sufficiently to aid the process. The
growth of the core would cause contraction because of in-
crease in the volume of the denser material, but it would also
release gravitational energy in the form of heat at the mantle-
core boundary. The heat would raise the temperature of the
mantle and cause thermal expansion and changes in min-
eralogical constitution to less dense forms. These would only
partly offset the general contraction by core growth. If the
effects were periodic, however, it may explain periods of
greater heat flow and tension in the crust (produced by ex-
pansion in the mantle) alternating with periods of contrac-
tion. Additionally, the heat may cause circulation of matter
in the mantle, but we will return to this aspect later. Ulti-
mately, when the core reaches its maximum size, cooling
would set in as a general condition.

An alternative but highly controversial theory postulates
core growth by an entirely different mechanism. Instead of be-

ing composed of iron-nickel, the core is considered to have the
same chemical composition as the mantle but to be changed
in physical state by the very high pressures and temperatures
that exist deep in the earth. The minerals have broken down
into simpler constituents and the atoms have been ionized,
that is, electrons have been stripped off the outer shells that
surround the atomic nucleii. The electrons are free to wan-
der and the material is then in a metallic state (i.e., a good
conductor of electricity). The breakdown of the crystalline
state would mean also that the core behaves as a liquid.
Thus, flow in this metallic-state core could equally well gen-
erate the earth's magnetic field as it would in a liquid iron-
nickel core. Continuing increase in size of such a core would
again lead to shrinkage of the earth's radius and also to re-
lease of gravitational energy as heat, with the attendant effects
described above.

The major difficulties that have been placed in the way of
the acceptance of any contraction hypothesis are the exten-
sive system of mid-ocean ridges with their median rifts and
transcurrent faults with evidence of large horizontal move-
ments such as the San Andreas of California and the Alpine
fault of South Island, New Zealand. The median rifts and
their extension in the Red Sea and East African rift valleys
imply major tensional forces pulling the crust apart. This is
contrary to the state of compression which should reign in the
crust if the earth is contracting. Likewise, it is difficult to
explain large horizontal crustal shifts and also the movements
and crustal tension deduced for many earthquakes of the
circum-Pacific region if the crust is subject to compression.

However, it may be argued that there is another internal

process to explain the crustal rifting, while orogenesis may still
arise mainly through contraction, particularly if the two effects
should operate more or less alternatively and periodically as
noted above. Some geologists maintain that the earth is not
contracting and is, in fact, expanding and that major earth
structures can be better understood in an earth of gradually
increasing radius. So we shall now turn to an examination
of these ideas.

Expanding Earth Hypotheses
The concept of an expanding earth was first suggested
about the turn of the century but has received more attention
during the last ten years. It was put forward by some as an
explanation of the theory of continental drift, i.e., the separa-
tion of the Americas from Europe and Africa was brought
about by the expansion of the mantle and the rupturing of
the crust and its separation to form the Atlantic Ocean. Car-
ried to the extreme, some even advocate that the area of the
present sialic crust (area of the continents plus the area of
the surrounding seas down to an arbitrary depth) equals the
area of the earth at the time when the crust was largely
formed. This means the surface area was then a little under
a third of what it is at present and the radius would have been
only just over half of that of today's earth. The mantle and
core would have expanded while the cooled thin sialic crust
remained about the same in size; the crust was thus rent into
pieces and dispersed into the pattern of the existing conti-
nents. The great system of median rifts along the mid-ocean
ridges has been cited as evidence for expansion of the earth
with the rifts representing the tearing apart of the crust and
the development of new oceanic crust by extrusion of magma

Diagrammatic representation of an expanding earth; the continents are nearly coalesced at an early stage — LEFT, but have spread apart as
the earth expanded — RIGHT. The continents remain essentially the same size but new oceans have formed.

FEBRUARY Page 9

from the mantle. Rifting of the continental crust would be
marked by the African and Red Sea rifts, with the formation
of a new ocean in the case of the latter.

Theoretical considerations of the evolution of the earth's
interior have led some to postulate expansion. Thus, heat
produced by decay of radioactive elements has been sug-
gested as a source of thermal expansion; in general, calcula-
tions indicate, however, that this source is insufficient to
explain any notable increase in volume. Another idea is
that the earth's core is composed of matter in a very dense
state and that this is unstable and changing slowly but con-
tinually into a less dense form. The volume increases, but in
addition the energy released would cause thermal expansion
and further mineralogic changes in the mantle. Contrary
to this is the hypothesis of gradual core growth, during
which the release of gravitational energy may suffice to
cause enough expansion of the mantle to more than com-
pensate for the contraction inherent in the increase of the
dense core. Lastly, there is the very interesting postulate that
the value of the universal gravitational constant is decreasing
with time: this is related to the theory of the expanding uni-
verse. If gravity is decreasing, then the pressures within the
earth are decreasing; this would cause expansion and also
changes in the mineral structures to less dense forms and per-
haps change of dense core material to less dense mantle mate-
rial (assuming a non-iron core).

Geological data on the extent of the seas that have period-
ically inundated the continents during the last 600 million
years have been interpreted as showing that the area of the
incursions has steadily diminished to the present. This is
taken to indicate earth expansion on the assumption that
the continental sial area has remained much the same while
the oceanic areas have increased.

Expansion has been utilized not only as the underlying
force for continental drift but also for mountain building.
The crust ruptures along the median rifts of the mid-oceanic
ridges, and new crust is formed from the upper mantle. Ac-
cording to one view, deep sea trenches are formed by tension
associated with deep mantle fractures (deep earthquake zones)
which occur at the boundary of oceans and continents. Fill-
ing of the trenches produces geosynclines and hot volatile ma-
terial, differentiated from the deep mantle, migrates up the
fractures resulting in volcanism and melting of the deep crust
and production of granite; increased temperature and deep
burial cause metamorphism of the sediments. Compressional
folding and thrusting are effected by the granite masses and
by the increase in radius of the crust consequent on expan-
sion, as well as possibly by crustal rotation arising from the
development of new oceanic areas. Thus, the Pyrenees
Mountains between France and Spain were supposed to have
been formed by compression as the present North Coast of
Spain separated from France forming the Bay of Biscay.
Spain rotated southward around a pivot at the west end of
the mountains and the region to the east of the pivot was
compressed and folded forming the Pyrenees. Isostatic re-
sponse to the thickened and granite-intruded crust causes
emergence accompanied by sliding and folding of sediments
from the uplifted mass. In these ways expansion forces are

Compression of mountain range during twisting movement
of a crustal block during earth expansion and Jormation
of the Bay of Biscay.

used to explain the process of mountain building and all the
attendant phenomena which traditionally had been explained
as caused by a regime of contraction in the earth. Previously
we have seen that the contraction theories have problems,
particularly in the existence of the world-wide oceanic ridge-
rift system. How then can the expansion theories be assessed?

There is little concrete evidence available on which to
base estimates of possible earth expansion independent of geo-
logical interpretations. Calculations based on the postulated
decrease of the gravitational constant suggest that the earth
may have increased its area by some 5.5 to 6% during its total
history (this means an increase in radius of only 0.002 of an
inch per year). Estimates of radius increase over the last 200
million years based on paleomagnetic measurements on rocks
of that age from widely separated localities on the same con-
tinent are not yet good enough to be used with confidence;
it is suggested, however, that they do indicate a slow increase
of between about 0.01 and 0.07 of an inch per year, depend-
ing on the data used.

Another possible source of information depends on the
earth's rotation. If the earth was smaller in the past, it
would have rotated more rapidly and there would have been
more days in the year. Study of the growth pattern of corals
that lived some 350 to 400 million years ago indicates that
there were then about 400 days in the year. Assuming that
the increase in the length of day since then is entirely due to
expansion, the earth's radius has been increasing at a rate of
about 0.026 of an inch per year. Unfortunately, tides caused
by the moon's and sun's gravitational fields also affect the
speed of rotation, rendering it very difficult to disentangle the
various effects. Calculations have been made that attempt
to separate the lunar tide component, and these still support
a very slow expansion, rather than contraction, of the earth.

Page 10 FEBRUARY

Expansion on a scale large enough to explain the drift
of continents and the production of the Atlantic and Indian
Oceans during the last 200 million years (amounting to an in-
crease of about 36% of the present surface area, or an increase
in radius of 0.2 of an inch per year) is apparently unexplain-
able by any possible means. Slow expansion over 3J^ to 4
billion years, assuming the present sialic crust area was once
the total surface area and requiring an increase of 70% of the
present surface area and of 0.03 of an inch per year in radius,
remains a possibility on the basis of existing data. It is re-
garded as unlikely by some and certainly there is no evidence
that the sial ever completely covered the earth.

The suggestion has also been made that the area of the
mid-ocean ridges represents new crust formed during expan-
sion. The ridges cover about 12% of the total area and, if this
is averaged over the greater part of the earth's history, the nec-
essary expansion (a radius increase of only 0.004 of an inch
per year) is very reasonable. However, the data available
about the ridges indicate that they are geologically young
features. If it is assumed they developed during the last 200
million years, then the amount of expansion becomes excessive.

It thus seems possible that the earth may have slowly ex-
panded, but probably not at the rate some theories de-
mand. Other causes are needed to explain features such as
mid-ocean ridges and complex mountain ranges. While
crustal rifting may be plausibly explained by an expanding
earth, it does not seem possible to explain the totality of effects
which are involved in the development of an orogenic belt,
particularly the early subsiding geosynclinal stage.

This article will be continued in a subsequent issue of the Bulletin.

ANTON BRUUN (continued from page 4)

The deepest dive was along the base of the spectacular
pinnacle pictured on page 3, named Peterborough Cathedral.
The water was quite clear. The bottom consisted of huge
rounded boulders piled together, black and bare or gray-
green when covered with algae and encrusting invertebrates.
Long-spined sea urchins were scattered everywhere on the
rocks and not together in clumps as is so often the case on a
coral reef. The largest fishes here were moray eels but there
were also bright red scorpion fishes, a brilliant pink sea bass,
and a beautiful yellow butterfly fish boldly marked with black
transverse bands. Most of the fishes were red, green or
black and had to be searched out in the crevices or under
the kelps.

Mas a Tierra, the island of the Juan Fernandez Islands
nearest the mainland, is strikingly different from San Felix.
Mas a Tierra has 3,000-foot ridges, sufficiently high for clouds
to gather. This produces abundant rainfall on at least part of
the island so the valleys have trees and most of the slopes dark
green shrubbery. There are also barren ridges where the soil
is thin; even these usually have some grass. About 600 peo-
ple, mosdy Chilean fishermen, live in one village; their main
occupation is tending spring-lobster traps. The lobsters are
kept alive in floats and once a week a seaplane calls to carry
them to the Chilean market.

The water around Mas a Tierra was several degrees colder
than at San Felix. The pine-cone and butterfly fishes were
absent but otherwise the varieties of fishes at these two iso-
lated, widely-separated localities were very much alike.

Perhaps half of the species of shore fishes around these is-
lands are the same as those found on the mainland. Most of
the remainder appear to be endemic species. Some of these,
such as the pine-cone fish and deep-bodied snipe-fish, have
their nearest relatives in New Zealand, Southern Australia or
South Africa. The nearest relative of the strange butterfly
fish has not been determined, but certainly it is very different
from any American species.

The specimens have been sent to the Smithsonian Sorting
Center and to Scripps Institute of Oceanography where they
will be sorted and labeled. Certain groups are to be sent to
specialists for study and eventual publication. The remain-
der will be available in institutions like Chicago Natural His-
tory Museum, for study by staff, visitors and students. The
Anton Bruun, returned to its labors, still criss-crosses the sea,
gathering the evidence which will in the years to come con-
tribute to a fuller portrait of the Pacific.

The Anton

Bruun

FEBRUARY Page 11

FOUR TRUSTEES

ELECTED TO MUSEUM BOARD

After a recent trustees' meeting, James L. Palmer, President of Chicago Natural
History Museum, announced the election of four new trustees to the Museum's
board. They are Harry O. Bercher, President of International Harvester Com-
pany, Paul VV. Goodrich, President of Chicago Title and Trust Company, Remick
McDowell, Chairman of The Peoples Gas Light and Coke Company, and E. Leland
Webber, Director of Chicago Natural History Museum.

Mr. Bercher has been president and chief executive officer of International
Harvester Company since 1962. He has been associated with the company for
37 years, having joined the firm immediately after his graduation from the Uni-
versity of Illinois. He serves on the boards of a number of civic and cultural
organizations.

Harry 0. Bercher Paul W. Goodrich Remick McDowell E. Leland Webber

Mr. Goodrich, who has been president of Chicago Title and Trust since 1952,
is a trustee of the Metropolitan Crusade of Mercy, Chicago Wesley Memorial
Hospital, and Drake University. He is also vice president of the Chicago Central
Area Committee.

Mr. McDowell, a graduate of the University of Chicago, joined Peoples Gas
in 1940, and has been a corporate officer since 1942. He was elected chairman
of the company in 1961 . He is also a director of the Chicago Central Area Com-
mittee and chairman of the board of trustees of the Institute of Gas Technology,
a research affiliate of the Illinois Institute of Technology, and chairman of its
executive committee.

Mr. Webber graduated from the University of Cincinnati in 1942, joined the
staff of the Museum in 1950, and was elected Director in 1962. He is a member
of the Board of the Illinois State Museum, the Council of the American Associa-
tion of Museums, and of the Board of Directors of the Y.M.C. A. Hotel of Chicago.

This month's cover is a photograph entitled "Tempting Food" taken by
Mr. T. S. Lai, of Quilon, India and selected for showing in the 21st Chicago
International Exhibition of Nature Photography, on view in Stanley Field
Hall through February 27th. The south Indian fruit bat, about to land on
its lunch, some small "finger" bananas, was photographed on an Indian
farm. An examination of skull and teeth characters would be required for an
accurate scientific identification of Mr. Lai's bat, since there are several sim-
ilar species in India. The photograph does show, however, that it is a hand-
some animal — for a bat.

Page 12 FEBRUARY

CHICAGO NATURAL

HISTORY MUSEUM

Founded by Marshall Field, 1893
Roosevelt Rd. and Lake Shore Dr.
Chicago, Illinois 60605
Area Code 312, 922-9410

BOARD OF TRUSTEES

Lester Armour
Harry 0. Bercher
William McCormick Blair
Bowen Blair
Walter J. Cummings
Joseph N. Field
Paul W. Goodrich
Clifford C. Gregg
Samuel Insull, Jr.
Henry P. Isham
William V. Kahler
Hughston M. McBain
Remick McDowell
J. Roscoe Miller
William H. Mitchell
James L. Palmer
John T. Pirie, Jr.
John Shedd Reed
John G. Searle
John M. Simpson
Edward Byron Smith
Louis Ware
E. Leland Webber
J. Howard Wood

OFFICERS

James L. Palmer, President

Clifford C. Gregg, First Vice-President

Joseph N. Field, Second Vice-President

Bowen Blair, Third Vice-President

Edward Byron Smith,

Treasurer and Assistant Secretary

E. Leland Webber, Secretary

DIRECTOR OF THE MUSEUM

E. Leland Webber

CHIEF CURATORS

Donald Collier,

Department of Anthropology

Louis 0. Williams,

Department of Botany

Rainer ganger I,

Department of Geology

Austin L. Rand,

Department of ^oology

BULLETIN

Edward G. Nash, Managing Editor
Beatrice Paul,

Kathleen Wolff,

Associate Editors