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4 


National Museum 
of Natural Sciences 


ae National Museums 
of Canada 
team 


Ottawa 1982 
/ Publications in Botany, No. 12 


THE LAKE ATHABASCA SAND DUNES 
OF NORTHERN SASKATCHEWAN 
AND ALBERTA, CANADA 


l. THE LAND AND VEGETATION 


** 


Hugh M. Raup | 
Harvard Forest f 
Petersham, Massachusetts BAD A 
U.S.A. 01366 BDNy 
$ bi 
E 


George W. Argus 
Botany Division 
National Museum of Natural Sciences 
Ottawa, Ontario, Canada K1A O0M8 


Publications de botanique, n° 12 
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Ausees nationaux Musée national 
dt Canada des sciences naturelles 


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National Museums National Museum 
of Canada of Natural Sciences 


Ottawa 1982 
Publications in Botany, No. 12 


THE LAKE ATHABASCA SAND DUNES 
OF NORTHERN SASKATCHEWAN 
AND ALBERTA, CANADA 


l. THE LAND AND VEGETATION 


Hugh M. Raup 
Harvard Forest 
Petersham, Massachusetts 
U.S.A. 01366 


and 


George W. Argus 
Botany Division 
National Museum of Natural Sciences 
Ottawa, Ontario, Canada K1A 0M8 


Publications de botanique, n° 12 


Musées nationaux Musée national 
du Canada des sciences naturelles 


National Museum of Natural Sciences 
Publications in Botany, No. 12 


Published by the 
National Museums of Canada 


©National Museums of Canada 1982 
National Museum of Natural Sciences 
National Museums of Canada 
Ottawa, Canada 
Catalogue No. NM. 95-9/12E 


Printed in Canada 


ISBN 0-662-11264-4 
ISSN 0068-7987 


Musée national des sciences naturelles 
Publications de botanique, n° 12 


Publié par les 
Musées nationaux du Canada 


©Musées nationaux du Canada 1982 
Musée national des sciences naturelles 
Musées nationaux du Canada 
Ottawa, Canada 
N° de catalogue NM. 95-9/12E 


Imprimé au Canada 


ISBN 0-662-11264-4 
ISSN 0068-7987 


Table of Contents 


INTRODUCTION 1 
MATERIALS FOR THE PRESENT STUDY 3 


GEOLOGY AND PHYSIOGRAPHY 4 
General Geology 4 
Deglaciation 4 
Postglacial Lakes 4 
Deglaciation and Tentative Dating of the Postglacial Lakes 10 


PHYSIOGRAPHY OF THE SANDSTONE AREA SOUTH OF LAKE ATHABASCA 12 


GEOGRAPHIC DISTRIBUTION AND EXTENT OF AEOLIAN SAND IN NORTHERN 
SASKATCHEWAN AND IN THE CONTINENTAL NORTHWEST TERRITORIES 16 


THE ADVANCE OF FORESTS AND THE POSTGLACIAL XEROTHERMIC PERIOD 18 
The Trees 18 
The Probable Pattern and Chronology of Advance 20 
The Advance of Forest South of Lake Athabasca 25 


SUGGESTED TIMES OF AEOLIAN SAND ACTIVITY = 25 


SHORE PROCESSES IN THE LAKE ATHABASCA SAND DUNE REGION 27 
Wind Directions 27 
Wave Action 27 
Ice Push 27 
Beaches 29 
Shore Ridges 29 
River Deltas 30 


PLANT HABITATS IN REGIONS OF ACTIVELY BLOWING SAND | 31 
Dunes and Dune-forming Processes 31 
The Sand Supply 32 
Aeolian Depositional Features 32 

Parabolic Dunes 32 
Oblique Ridge Dunes 36 
Transverse Dunes 38 
Precipitation Ridges 41 
Other Sand Features 41 
Sand Hillocks 41 
Sand Sheets 43 
Rolling Dune Topography 43 
Aeolian Residual Features 45 
Gravel Pavements 45 
Dune Slacks 47 
Stabilized Aeolian Topography 48 


THE VEGETATION OF THE SAND DUNE REGION 49 
Actively Blowing Sand 50 
Seed Germination and Seedling Establishment 51 
The Vegetation in Areas of Active Sand 53 
Hillock and Cushion Dunes 54 
Rolling Dune Topography 54 
Transverse Dunes 55 


ill 


Oblique Ridge Dunes 59 
Parabolic Dunes 61 
Gravel Pavements 63 
Dune Slacks and Buried Drainageways 66 
The Vegetation on Stabilized Aeolian Topography 69 
Forests on Dry Sites 69 
Forests on Intermediate (“Mesophytic”) Sites 71 
Wetland Vegetation 72 
Muskeg Forest 73 
Muskeg Shrub 74 
Muskeg Grass-Sedge Meadow 75 
Grass-Sedge Meadow on Sand_ 75 
Aquatic Vegetation 76 
Minor Habitats 76 


ACKNOWLEDGEMENTS 76 
LITERATURE CITED 78 


APPENDIX A. SAND DUNE FIELDS AND PARABOLIC DUNES SOUTH OF LAKE 
ATHABASCA 81 
The Maybelle River Sand Dunes 81 
The William River Sand Dunes 81 
The Thomson Bay Sand Dunes 85 
The Archibald Lake Sand Dunes 86 
The Wolverine Point Sand Dunes 87 
The MacFarlane River Sand Dunes 89 
Unvisited Saskatchewan Sand Dunes 89 


APPENDIX B. CHECKLIST OF THE FLORA OF THE SOUTH SHORE OF LAKE 
ATHABASCA 91 
Vascular Plants 91 
Bryophytes 94 
Liverworts 94 
Lichens 94 


Abstract 


In northwestern Saskatchewan and in adjacent 
Alberta is a region of active sand dunes and desert- 
like topography that is unique botanically. Most 
of this region is underlain by Athabasca Sand- 
stone from which the dune sand and gravel have 
been derived. During the recession of the Keewatin 
ice from the Mackenzie Basin, beginning 13 000- 
14 000 years ago the rivers flowing northward to 
the Arctic were impounded to form large pro- 
glacial lakes. By about 8500 years B.P. these lakes 
had been drained by the removal of ice from the 
Mackenzie valley to form glacial Lake McConnell. 
The shores of this lake have continued to be 
lowered, but much-more slowly due to isostatic 
uplift in the eastern parts of the Athabasca and 
Great Slave Lake basins. It is proposed that these 
two lakes became separate bodies of water about 
3300 years ago when the Fort Smith escarpment 
came to the surface. The sandy plain south of Lake 
Athabasca is believed to have been thus exposed 
rapidly at first, but more slowly in the last 8500+ 
years. 

The history and development of the sand dunes 
are closely linked to the lake shore processes that 
were effective during the past 9000-10 000 years. 
Strong winds were blowing over wide expanses of 
open water and over lands that were progressively 
exposed by the drainage of the lake and by 
isostatic rebound. Probably until 4000-5000 years 
ago the winds over most of the land were un- 
obstructed by forests. The winds produced off- 
shore bars and sandy beach ridges that were 
accentuated by ice push and transformed by the 
wind. 

Habitats available for plant colonization in the 
region of actively blowing sand vary from dry 
sand, continuously blown about by the wind, to 
relatively stable soil surfaces. About 270 kinds of 
vascular plants, lichens, and mosses grow here. 
Aeolian sand appears in the form of sand dunes 
and sand sheets. The parabolic dune is the most 
common dune form in the region. The most 
conspicuous dunes in the active dune fields are the 
oblique ridge dunes that may reach heights of 35m 
above their bases. Large areas of rolling dunes and 
transverse dunes also occur in the active dune 
fields. Bordering the dune fields are precipitation 


ridges that invade forests, wetlands, rivers, and 
lakes. Gravel pavements appear as plains or ridges 
covered with a veneer of gravel often scoured and 
polished by wind and sand to form ventifacts. In 
dune slacks between active sand dunes the water 
table is sometimes exposed. Surrounding the open 
dune fields are extensive regions of stabilized 
aeolian topography covered by forest and wetland 
vegetation. Parabolic dunes often form in these 
areas following fire or other disturbance. These 
areas show their aeolian origins by the presence of 
stabilized dunes and ventifacts. 

The vegetation of areas of active sand is made 
up of relatively few species but they occur in many 
combinations. Seedlings become established main- 
ly in the moist to wet dune slacks, but a few species 
can establish themselves on the lee slopes of active 
dunes, on the dry gravel pavements, or on open 
sand plains. Vegetation within the active sand 
areas follows a cyclical pattern of establishment, 
burial, and re-exposure as the dunes move across 
the landscape. Seeds germinate and seedlings may 
become established in a moist dune slack. As a 
migrating dune invades the slack some plants are 
buried and killed and others remain above the 
sand surface by vegetative growth. In time, some 
of these plants appear on the lee slope and crest of 
the dune, but finally they are killed when they are 
excavated as the dune continues its migration. The 
gravel pavement habitat is relatively stable, but 
few species occupy it. Only about 10 species of 
vascular plants occur here, some of which are tap- 
rooted perennials with arctic affinities. 

On stabilized sand areas the most common 
forest type is open Pinus banksiana-lichen forest. 
Over 60 species occur in this habitat but the 
floristic composition at any one place may be very 
simple, sometimes consisting of only one or two 
vascular plant species. Mesophytic forests on 
floodplains and ridges are floristically variable, 
and the primary species may be various combina- 
tions of Pinus banksiana, Picea mariana, P. 
glauca, and Betula papyrifera. Wetlands are com- 
mon and appear in the form of muskeg forested 
with Picea mariana and Larix laricina, muskeg 
shrub vegetation, and grass-sedge meadows. 


Résumé 


Dans le nord-ouest de la Saskatchewan et la partie 
adjacente de |’Alberta se trouve une région aux 
dunes vives et aux reliefs semi-désertiques qul, au 
point de vue de la botanique, ne ressemble a 
aucune autre. La plus grande partie de cette région 
repose sur une couche de grés de |’Athabasca, dont 
sont issus le sable et le gravier des dunes. Au cours 
du retrait des glaces du Keewatin, qui ont com- 
mencé a se retirer du bassin du Mackenzie il ya 13 
ou 14000 ans, les riviéres qui coulaient vers le 
nord jusqu’a l’Arctique se trouvérent endiguées, 
donnant naissance a de grands lacs. Dés 8 500 ans 
avant le présent, ces lacs avaient été drainés par le 
retrait des glaces obstruant la vallée du Mackenzie, 
et avaient formé le lac glaciaire McConnell, dont 
les rives s’abaissent encore, mais beaucoup plus 
lentement a cause du soulévement isostatique des 
parties orientales des bassins de l’Athabasca et du 
Grand Lac des Esclaves. On a avancé l’hypothése 
que ces deux lacs sont devenus des nappes dis- 
tinctes il y a environ 3 300 ans, lorsqu’affleura 
l’escarpement de Fort Smith; la plaine sablonneuse 
située au sud du lac Athabasca aurait été ainsi mise 
a découvert d’abord rapidement, puis plus lente- 
ment au cours des derniéres 8 500 années, plus ou 
moins. 

L’histoire et le développement des dunes sont 
étroitement liés a la transformation des rives 
depuis 9 a 10 000 ans. Des vents violents soufflaient 
sur de vastes étendues d’eaux libres et sur des 
terres qui €mergeaient peu a peu par suite du 
drainage des lacs et du relévement isostatique. 
C’est probablement il y a 4 ou 5 000 ans que des 
foréts commencérent a faire obstacle aux vents qui 
jusqu’alors balayaient presque toutes les terres. 
Ces vents produisirent des cordons littoraux et des 
crétes de plage sablonneuses, accentués par la 
pression des glaces et transformés par le vent. 

Dans cette région ou le sable se meut continuelle- 
ment, les habitats susceptibles d’accueillir la vie 
végétale varient, la gamme allant de ceux qui sont 
recouverts de sable sec, constamment véhiculé par 
le vent, a ceux ow les sols ont des surfaces 
relativement stables. Environ 270 espéces de plantes 
vasculaires, de lichens et de mousses y croissent. 
Le sable éolisé se présente sous forme de dunes et 
de nappes, la dune parabolique étant la dune dont 
le type est le plus répandu dans la région. Dans les 
champs de dunes vives, les dunes les plus remar- 


quables sont les dunes aux crétes obliques dont la 
hauteur s’éléve parfois jusqu’a 35 métres a partir 
de la base. Les champs comptent aussi bon 
nombre de dunes onduleuses et transversales. En 
bordure des champs de dunes, des crétes envahis- 
sent par vagues successives les foréts, les maréca- 
ges, les riviéres et les lacs. Des sols de gravier 
apparaissent sous forme de plaines ou de crétes 
recouvertes d’une pellicule de gravier aux éléments 
souvent décapés et polis par le vent et lesable pour 
former des cailloux éolisés. Dans les creux qui 
séparent les dunes vives, la nappe phréatique 
affleure parfois. Les champs de dunes sont entourés 
de vastes régions a la topographie éolienne stabi- 
lisée, couvertes de foréts et de végétation maréca- 
geuse. Des dunes paraboliques s’y forment souvent 
a la suite d’un incendie ou d’une autre perturbation. 
L’intervention du vent se manifeste par la présence 
de dunes stabilisées et de cailloux éolisés. 

La végétation des zones de sable actif est 
constituée d’un nombre relativement restreint 
d’espéces aux combinaisons toutefois multiples. 
Les jeunes plantes s’établissent principalement 
dans les creux moites ou humides, mais quelques 
espéces peuvent se fixer aux pentes sous le vent des 
dunes vives, sur les sols de gravier sec ou dans les 
plaines de sable libre. Dans les zones de sable actif, 
la végétation suit un cycle: établissement, en- 
fouissement et réapparition a mesure que les dunes 
se déplacent a travers le paysage. Des graines 
germent et de jeunes plantes peuvent apparaitre 
dans un creux humide. Lorsqu’une dune en migra- 
tion envahit le creux, certaines plantes sont en- 
sevelies et tuées tandis que d’autres restent au- 
dessus de la surface du sable a cause de leur 
croissance végétative. Avec le temps, certaines 
d’entre elles apparaissent sur la pente sous le vent 
et la créte de la dune, mais elles sont finalement 
déracinées et périssent lorsque la dune poursuit sa 
migration. Le sol de gravier constitue un habitat 
relativement stable, mais rares sont les espéces qui 
loccupent. N’y poussent qu’environ 10 espéces 
vasculaires, dont certaines plantes vivaces a racine 
pivotante proches de la végétation arctique. 

Dans les zones de sable stabilité, le type forestier 
le plus répandu est celui de la forét claire a 
dominante de Pinus banksians et de lichens. Plus 
de 60 espéces vivent dans cet habitat, mais la 
composition floristique a un endroit quelconque 


peut étre trés simple et consister parfois en une ou 
deux espéces de plantes vasculaires. Les foréts 
mésophytiques des plaines inondables et des crétes 
ont une flore qui varie, les principales espéces 
pouvant étre diverses combinaisons de Pinus 
banksiana, Picea mariana, P. glauca et Betula 


Vill 


papyrifera. Les terres humides sont communes et. 
se présentent sous forme de muskegs aux foréts de 
Picea mariana et de Larix laricina, de muskegs a 
végétation arbustive ou de prairies d’herbes et de 
carex. 


Introduction 


On the south shore of Lake Athabasca in north- 
western Saskatchewan lies a great sand “desert,” a 
wilderness area of shifting sand, high sand dunes, 
and gravel pavements covered with wind sculp- 
tured and polished stones. The active dunes are 
invading and overwhelming the surrounding for- 
ests which are unable to stabilize the moving sand. 
The very sparse vegetation of the active sand is 
made up of a unique assemblage of plants derived 
from arctic, boreal, and Great Plains elements. 
Some of these are disjunct from their parent 
populations, and others are endemics which occur 
only in the sand dune region. 

The desert-like areas of loose sand lie bordering 
on or within about 1.5 km of the lake shore and 
most of them subtend that portion of the shore 
between Ennuyeuse Creek and the MacFarlane 
River. To the west, in northeastern Alberta, there 
is a small area of open sand west of the Maybelle 
River and another west of the Richardson River. 
The sand dune fields range in altitude from about 
214 m, a meter or two above the elevation of Lake 
Athabasca, to about 335 m above sea level. The 
largest areas of active aeolian sand are located 
where the William and the MacFarlane Rivers 
meet the lake. Between these points, and paral- 
lelling the lake shore, are a number of smaller 
open dune areas (Figure 1 and Appendix A). 

The active dune system consists of complexes of 
sand dunes ranging from ridges up to 35 m high 


William Turnor Pt 


Beaver Pt 


oO S) 


q, a4 ara ~ 


x3 


unstabilized by vegetation to low dunes thinly 
covered by grasses and shrubs. In places sand 
dunes are moving across partially stabilized gravel 
pavements and exposed water tables or they form 
unstable sheets of loose sand. Except in a few 
places where sand comes out to the lake shore, the 
areas of active sand are surrounded by more 
stabilized sand plains, dunes, or elongated sandy- 
gravel ridges. 

The Lake Athabasca sand dunes were known in 
prehistoric times to travellers who left behind 
stone tools and projectile points that mark their 


Figure | 


Map of the active 
sand dune region 
south of Lake 
Athabasca. The 
active dunes are 
shown as stippled 
areaser. The’) field 
camps of our 
parties are shown 
as triangles. 


Poplar Pt 


Wolverine Pt 


piequu?™ 


presence (Wright, 1975). Small “workshops” in 
the form of boulders surrounded by flakes pro- 
duced in the fabrication of stone tools have been 
found in some of the boulder deposits associated 
with gravel pavements. The earliest written record 
of the existence of the sand dunes was made in 
1791 by Philip Turnor who wrote that as he 
approached the delta of the William River he 
could, “see about 3 miles East and round to SSW 
all a rising sandy desert of a yellowish white 
Colour with a chance scub pine standing singly” 
(Tyrrell, 1934, p. 427). As he passed the Mac- 
Farlane River he saw, “heigh sandy hills which 
when seen off the mouth of the river looks like 
fields of ripe corn between ledges of woods such as 
are seen in the Hill countrys of England” (Tyrrell, 
1934, p. 429). 

Turnor’s was not only the first mention of this 
great sand dune area but the only one for 100 years 
until the geologist D.B. Dowling travelled up the 
William River in 1892 and noted, “on the surface 
of the plateau, which is mostly bare, sand-hills rise 
in some cases nearly a hundred feet above the 
general level” (Tyrrell & Dowling, 1897, p. 70D). 
These brief observations were not developed fur- 
ther by Dowling, who gave the name “Athabasca 
Sandstone” to the horizontally bedded Pre- 
cambrian formation underlying the terrain. Inex- 
plicably, the early explorers who visited the south 
shore of Lake Athabasca did not seem to rec- 
ognize the uniqueness of the great sand “desert” 
that lay to the south. It was not until the 1920’s and 
1930’s, when aerial photographs became avail- 
able, that there was a full realization of the 
distribution and extent of the active sand dune 
areas. But there are other reasons for the silence 
about the sand dunes over so many years. 

On a stormy day the pinkish reflection of the 
wet sand on the low lying clouds may serve as a 
beacon to travellers, but the south shore of Lake 
Athabasca is not hospitable. The lakeshore from 
Ennuyeuse Creek to the MacFarlane River is 
characterized by wide sand beaches and sandy 
shoals. Travel by canoes or other small boats is 
hazardous because northwesterly and northeast- 
erly winds are frequent and often violent, making 
it imperative to get boats and their contents ashore 
quickly. Safe anchorages are nonexistent. The 
result has been routine avoidance of the south 
shore by nearly all travellers on the lake; only two 
or three trapper’s cabins are to be found there. 

To the casual visitor the aeolian sand areas 
appear to be covered very sparsely by plants and to 


resemble sand dunes of the maritime coasts of 
North America. The botany of the sand dunes was 
first studied by H.M. Laing who accompanied the 
naturalist Francis Harper to Lake Athabasca in 
1920. His plant collections are in the United States 
National Herbarium, but no report is known to 
have been written. The next botanical collections 
were made in 1935 by Hugh M. and Lucy G. Raup. 
The flora of the sand dunes proved to be inter- 
esting in that it consists of species that have been 
derived from the waves of arctic, boreal, and 
northern Great Plains floras that moved into the 
region following deglaciation and climatic amelio- 
ration. Among plants that were isolated in the 
active sand dunes are some that are morpholo- 
gically distinct from their parental populations 
and have been recognized as endemic taxa (Raup, 
1936). This in itself is remarkable because the 
Mackenzie Basin is not noted for its endemism, 
and the discovery of a pocket of endemics ina vast 
region otherwise devoid of them presents intri- 
guing problems in the evolutionary and geo- 
graphic history of the flora. 

Comparable areas of inland sand dunes in 
North America are few. The Lake Michigan sand 
dunes, described by Cowles in 1899 and later 
studied in detail by Olson (1958), and the Kobuk 
River sand dunes in Alaska (Fernald, 1964; Ric- 
ciuti, 1979) are the only similar areas of active sand 
dunes known to us. These areas, however, are 
much smaller in extend than the Lake Athabasca 
dunes and have different floras. The Lake Michi- 
gan flora has many deciduous forest taxa un- 
known in boreal Saskatchewan, but there are 
some species in common, as well as numerous 
species that occupy a similar niche and are ina 
sense vicariads. The floras of the Kobuk River 
dunes and the Lake Athabasca dunes, while 
different, have a number of species in common. 
The landscape of the Great Kobuk dunes 1s also 
similar in having active dunes up to 35 m high. 

Endemism in the Lake Michigan and Kobuk 
River dunes is much less than at Lake Athabasca. 
Oxytropis kobukensis Barneby is endemic to the 
Kobuk dunes and a sand dune ecotype of Astra- 
galus alpinus L. has been collected there (C.H. 
Racine, pers. comm.); but other taxa such as 
Deschampsia caespitosa (L.) Beauv., Salix ala- 
xensis (Anderss.) Cov., Silene acaulis!, Armeria 
maritima, and Tanacetum huronense that have 


'Authorities for taxa in the flora of the sand dune region are 
given in Appendix B. 


differentiated in the Lake Athabasca region, into 
Deschampsia mackenzieana, Salix silicicola, Si- 
lene acaulis f. athabascensis, Armeria maritima 
ssp. interior and Tanacetum huronense var. floc- 
cosum respectively, have apparently not under- 
gone similar changes in the Kobuk River region. 
In the Lake Michigan sand dunes the only en- 
demic appears to be Salix syrticola. Fern. (usually 
included in S. cordata Michx.) a willow that has 
the thickened and densely villous leaves similar to 
some of the Lake Athabasca Salix. 

In this paper we will describe the aeolian sand 
areas and their vegetation and place the area intoa 
broad geographic context. In order to rationalize 
the existence of endemic plants in the active sand 
dunes we will present a geographic study of 
aeolian sand habitats.as they existed or probably 
existed throughout postglacial time in northern 
Alberta and Saskatchewan and in the continental 
Northwest Territories. This will involve a review 
of events following the recession of glacial ice, the 
resultant landforms and soils, climatic changes 
during the period, the development of vegetation 
and the migration of native people and game 
animals into the region. We know that all these 
events happened in the 13 000-14 000 years since 
the glacial ice began to recede eastward from its 
western maximum extent, but, although some of 
the major events left clear marks in the landscape, 
the details remain hazy and speculative. 

Our study of the Lake Athabasca sand dunes is 
presented in two parts. In the first part the 
landscape—its physiography and vegetation and 
some phytogeographic relationships is described. 
The second part, to appear later, will catalogue the 
flora and will consider its geography and the 
nature and origin of botanical endemism in the 
Lake Athabasca region. 

We make no pretense to the completeness of this 
work. At best it can be regarded as a reconnais- 
sance set down here in the hope that it will 
stimulate further and more sophisticated study. 


Materials for the Present Paper 


Collections from the dune areas were made in 
1935 by Hugh M. and Lucy G. Raup. They spent 
the last week of July and all of August onthe south 
shore of the lake working from four base camps 
(Figure 1). 

1. Ennuyeuse Creek, 3 km west of its mouth: 

Lat. 59°03’, Long. 109°34’ 


2. William River, 1.5 km above its mouth: Lat. 
59°08’, Long. 109°19’. 

3. Wolverine Point, 3 km east of the point: Lat. 
59°09’, Long. 108°25’. 

4. Poplar Point, 8 km east of the point: Lat. 
59°30’, Long. 107°41’. 

Brief stops for collecting and reconnaissance 
were made at several other places. The vascular 
plant collections of 1935 were reported by Raup 
(1936) as were his notes on the forests south of the 
lake (Raup, 1946). Several endemic taxa found 
growing on the dunes were described and named 
in the 1936 paper, but numerous notes on the 
dunes and their vegetation have remained un- 
published. Data on shoreline and muskeg vegeta- 
tions in the dune areas, however, were used in a 
paper on species versatility in shoreline habitats 
(Raup, 1975). 

Later field work on the dune areas was done by 
George W. Argus in four visits between 1962 and 
1975. These trips were accomplished by air travel, 
which enabled him to approach the dunes from the 
south and to establish base camps on small lakes at 
or near the southern borders of the large dune 
areas where no studies had previously been made 
(Figure 1). During each visit both vascular and 
non-vascular plants were collected and notes 
made on the dunes and their vegetation. In 1963 
and 1972 living material was obtained for cultiva- 
tion. 

1. Maybelle River, lake at the head of the river: 
Lato8° 09. Lone, 110°53'..s0.euly 2 
August 1975, with David J. White, assistant. 

2. Ennuyeuse Creek, small lake at the head of 
the creek: Lat. 58°58’, Long. 109°20’. 10-15 
August 1975, with David J. White. 

3. William River, west side of the river 10 km 
from its mouth: Lat. 39°03", Long. {09711 
26-28 July 1972, with Thomas Kovacs, Parks 
Canada. 

4. Little Gull Lake: Lat. 59°02’, Long. 108°59’. 
26 June—-10 July 1962, with Robert W. Nero, 
ornithologist, George F. Ledingham, natu- 
ralist and F.H. Edmunds, geologist; 31 July— 
3 August 1963, with Robert W. Nero; 3-9 
August 1975, with David J. White. 

5. Archibald Lake: Lat. 59°09’, Long. 108°36’. 
29-30 July 1972. 

6. Yakow Lake, at the edge of the dunes: Lat. 
59°12’, Long. 108°02’. 17-23 July 1962, with 
Robert W. Nero. 


7. MacFarlane River, at the edge of the dunes 4 
km above the mouth of the river: Lat. 59°11’, 
Long. 107°55’, with Thomas Kovacs. 

Other recent research in the dune area was done 
in 1971 when Reinhard Hermesh, then a graduate 
student at the University of Saskatchewan, madea 
short reconnaissance visit to the sand dunes in 
May and then spent June, July, and August ina 
more detailed study. His unpublished thesis 
(Hermesh, 1972) contains a major contribution on 
the plant ecology of the dunes and will be referred 
to repeatedly in the present paper. He worked 
from the lake shore, from a camp at Ennuyeuse 
Creek, and from Thomson Bay. He visited the 
MacFarlane River dunes only briefly toward the 
end of the season. He investigated dune forms, 
especially their relations to winds and local water 
tables, and attempted a classification of them. 
Especially valuable are his studies involving exca- 
vation and illustration of the growth habits of 
dune plants. 


In the summer of 1977 Dr. Derald G. Smith, 
engaged in a long-term study of sand bars and 
channel braiding processes in the William River 
delta, prepared a reconnaissance report on dunes 
of the large fields on either side of the William 
River (Smith, 1978). He classified the dune forms 
and discussed the Athabasca Lake beaches and the 
formation of beach ridges. 

Between 1971 and 1976 Maureen Landals stud- 
ied the sand dune area between the Maybelle and 
Richardson Rivers in northeastern Alberta. The 
main objective of her study (Landals, 1978) was to 
assess this region as a potential park. In the course 
of her work she studied the dune forms, their 
origin, and their vegetation. 

Dr. Peter P. David included the Lake Atha- 
basca dune area in his general description of the 
sand dune topography of Canada. In his report 
(David, 1977) he assigned new names to the areas 
of aeolian topography in our region. The May- 
belle River dunes described in our paper are in his 
“Richardson River Sand Hills,” while all the 
others immediately south of Lake Athabasca, 
which we discuss in detail, are in his “Archibald 
Lake Sand Hills.” We prefer to retain the name 
“Lake Athabasca sand dunes” for our region not 
only because of its long usage (Raup, 1936; 
Hermesh, 1972; Rowe & Hermesh, 1974; Smith, 
1978) but also because the postglacial history of 
the area is closely related to the development of 
Lake Athabasca itself. 


Geology and Physiography 


General Geology 


A major geological boundary traverses central 
Saskatchewan, northeastern Alberta, and the Dis- 
trict of Mackenzie to Great Bear Lake and the 
arctic coast. East and northeast of this boundary 
is the Canadian Shield underlain by hard Pre- 
cambrian rocks: granite, gneiss, sandstone and 
quartzite, highly metamorphosed Archean sedi- 
mentary rocks, and volcanics. West of the bound- 
ary are mainly softer sedimentary rocks of 
Paleozoic or, at higher levels, Cretaceous age. This 
difference is reflected dramatically in the glacial 
drift deposits and the soils derived from them. 

Of particular significance to the present paper 
are the areas directly underlain by the Pre- 
cambrian sandstones, for they are the ultimate 
source of the Athabasca dune sands as well as of 
most of the aeolian sands of the region. The major 
areas of sandstone were mapped by Fahrig (1961) 
and are shown here as Figure 2 (with modi- 
fication). Probably the most extensive is the 
Athabasca Sandstone (Tyrrell & Dowling, 1897; 
Alcock, 1936; Blake, 1956; Fahrig, 1961) which 
underlies most of Lake Athabasca, appearing on 
islands in the lake and cropping out in a few places 
on the north shore. Eastward its border extends to 
Black and Wollaston Lakes, southward and 
southeastward to Cree Lake and the Mujatik 
River. It is bordered on the south and west by the 
Precambrian Shield margin, reaching Lake Atha- 
basca west of Old Fort River. 


Deglaciation 


The Keewatin ice sheet covered a vast region 
from Hudson Bay westward nearly or actually to 
the base of the Rocky and Mackenzie Mountains. 
There it met with Cordilleran ice or left in some 
places a corridor between. It appears to have 
started melting back about 13 000 to 14000 years 
ago (St-Onge, 1972; Ritchie & Hare, 1971; Craig & 
Fyles, 1960; Prest, 1969). Craig & Fyles (1960, p. 
10) have proposed that “The last remnants of the 
Laurentide ice-sheet west of Hudson Bay could 
not have survived much later than 7,000 years ago 
and may have disappeared earlier.” 


Postglacial Lakes 


With the recession of the ice, waters of the great 
rivers draining to the Arctic were impounded by 


fe 2y=>~— 0 Fort 
3 Reliance 


Uranium City 
() 
{ 


Athabasca cP 


Scale of Miles 
100 


Reindeer 


i. + | v | q 
CHEWAN ; 


Figure 2. Areas (stippled) underlain by sandstone bedrock in northwestern Canada Modified from 


Fahrig, 1961 (used with permission). 


the ice front to form a series of great lakes at 
progressively lower levels. These lakes covered 
wide areas in the depressions that now carry the 
major rivers and the great northern lakes. As the 
ice melted back across the Canadian Shield it 
formed smaller lakes of shorter duration in the 
drainage basins of such rivers as the Dubawnt, 
Thelon, and Back (see Craig & Fyles, 1960; 
Taylor, 1956). The glacial ice produced another 


effect which is of great significance in the history 
of these postglacial landscapes. It depressed the 
earth’s crust under its weight and, as the ice 
withdrew, upward readjustments took place. Firm 
data on this effect are inadequate for more than 
rough estimates of its magnitude and distribution. 

The earliest of the postglacial lakes in central 
Alberta mapped by Taylor (1960) is called “Miette 
Lake.” It was a narrow body of water, about 160 


km (100 mi) long and at an altitude of about 952 m 
(3450 ft) in the upper valley of the Athabasca 
River where the latter flows out from the Rocky 
Mountains through the foothills. It flowed into 
Lake Edmonton which flowed into the North 
Saskatchewan River. 

Another great lake system was in the Peace 
River basin. Taylor (1960) indicated that the 
uppermost deposits of this lake, which has been 
called “Lake Peace,” are at an altitude of 984 m 
(3225 ft). As the lake was lowered by the receding 
ice front, lacustrine deposits were laid down at a 
series of successive levels from west to east down 
to about 444 m (1750 ft) at which point the lake 
became confluent with the highest level of a large 
body of water which Taylor called “Lake Tyrrell” 
(Figuress): 

A long arm of Lake Tyrrell extended up the 
valley of the Peace River to the above altitude of 
about 444 m (1750 ft). Taylor (1960, p. 175) cited 
the work of Lindsay et a/. (1958b, map sheet 84-F; 
1960, map sheets 84-J & 84-K) who, “mapped 
three large areas of sandy aeolian and alluvial 
materials adjacent to the modern Peace River.” 


— 


‘ 


Caribou Mtn 


f EX 


BES . ISS 
SBASSS 
KSAX 


iN 


A» 


\ 
sar BS 


: fs Tm 
eee 


These deposits were 590, 1170, and 1271 km? (228, 
452, and 491 square miles) in area, with their 
upstream ends at elevations of approximately 427, 
336, and 275 m (1400, 1100, and 900 ft) above sea 
level, respectively. Taylor (1960, p. 175) inter- 
preted these as, “deltas . . ., whose materials have 
been partly reworked into dunes by wind action.” 
He regarded these deltas as evidence of still-stands 
in the drainage of Lake Tyrrell. Probably they 
correspond to the stages estimated earlier by 
Cameron (1922) at 488, 335, and 244 m (1600, 
1100, and 800 ft). Another long arm reached up 
the Athabasca River valley to an elevation of 
about 549 m (1800 ft) above sea level. This is at 
approximately the lower end of a series of sand 
dunes mapped by St-Onge (1972) and is at about 
the same place in the valley that marks the highest 
level of Lake Tyrrell on Taylor’s map. This 
elevation is very near the lowest level given by 
Taylor for the confluent Lake Peace (534 m or 
1750 ft). He extended Lake Tyrrell only provi- 
sionally into the present basin of Lake Athabasca. 
At the highest level of Lake Tyrrell, presumably 
attained while the Mackenzie Valley was still 


Y / 
pe e Be 
SSO on 2 
ca > LO 
Seek 

aie 


BAe 


KEY 


Watt Mtn. 

Ft. Chipewyan 

Lake Mamawi 

Ft. McMurray 

Peace Point 

Methy Portage 

Clearwater River 

Lac la Biche 

Beaver Lake 

Fond-du-Lac River 

—Wollaston Lake 
outlet (7) 

11. La Biche outlet 

12. Christina outlet(s) 

13. Ft, Vermilion 

14. Firebag River 

15. Marguerite River 


PW MAMIE WH rs 


_ 


Pleistocene 
delta 


Fevued v- 60 RST 
We 59 PST 


Figure 3. Approximate limits of glacial Lake Tyrrell. Lake Peace extends up the Peace River valley. From 


Taylor, 1960 (used with permission). 


obstructed by ice, its drainage probably was 
southeastward into the Churchill River basin 
(Taylor, 1960). 

Craig (1965) drew provisional boundaries of an 
ancestral Great Slave Lake, which he called “Lake 
McConnell” (Figure 4). From the locations and 
altitudes of old shorelines, deltas, and other 
features, Craig thought that this lake reached its 
greatest extent at approximately the present alti- 
tude of 282 m (925 ft) above sea level. This altitude 


Cory) wet 
ake R. O,, oY 
N PLATEAU ~&&> 


HOR 
EBBUTT 


(Bs 
eo 50 7 
DD! palt Simpson 


60° 


YUkon ° 
ae 2 ERR. 


BRitisy °° ee i 
| cof IN 


Maximum extent of 
Glacial Lake McConnell... ——~...** 


Kilometres 


120° 


79 


4 HILLS Ute So, “S 


for the highest known shores was found near Faber 
Lake, which is 80 km (50 mi) north northwest of 
the end of the North Arm of Great Slave Lake, and 
also near the northeast shore of Buffalo Lake. At 
this time the glacial margin was about at the 
western edge of the Canadian Shield, and the 
western extremity of the lake was in the upper 
Mackenzie valley, down at least to the Liard River 
(Craig, 1965). Using the elevations of deltas near 
Fort Simpson (153 m or 500 ft) and the one near 


— — 
——— 


max 


S Contwoyto 


— 


Lake 


Warburton 
Bay 


A Pig a 


Lake// fF 
Ue Fort 
esolution 


They GSC 


Figure 4. Glacial Lake McConnell. The approximate elevations (in feet) around the western extent of 
glacial Lake McConnell are from Craig, 1965, Fig. 2. Modified from Craig, 1965 (used with 
permission). 


Faber Lake (282 m or 925 ft), he estimated that the 
differential isostatic rebound in this area was a 
little over 38 cm per km (2 ft per mi). He proposed 
that the lowest delta mapped by Taylor in the 
Peace valley probably formed at the shore of Lake 
McConnell. He thought that Great Slave and 
Great Bear Lakes probably were also connected at 
this time. He did not have enough data to propose 
a position for the ice front in the Athabasca Lake 
basin; but he was convinced that when Lake 
McConnell was formed the Mackenzie drainage 
had already been restored and that subsequent 
drainage of the lake was caused by uplift in the 
eastern part of the basin. 

From the above notes, it appears that Lakes 
McConnell and Tyrrell overlapped in a strait 
perhaps 80 km (50 mi) wide over the Slave River 
valley. The lakes continued to be joined until the 
combined lake fell to about 206 m (675 ft) above 
sea level. At this level the bedrock escarpment, 
which now forms the Smith Rapids in the Slave 
River, was exposed at the surface. It formed a dam 
that held up Lake Athabasca while Great Slave 
Lake continued to fall. 

For convenience in the following discussion, 
only that part of the combined lake that was above 
the uppermost shores of Lake McConnell will be 
considered as Lake Tyrrell. 


N 


An eastward extension of Lake McConnell that 
covered all or most of the basin of the present Lake 
Athabasca now seems probable. Cameron (1922) 
thought that at his 335 m (1100 ft) level the lake 
covered approximately the western half of the 
basin, and that at his 244 m (800 ft) level all of the 
basin would be covered. Prest (1969) estimated 
that the Athabasca Lake basin was clear of ice by 
about 9000 years ago. If this estimate is correct, 
Lake McConnell probably had a long arm ex- 
tending into the Athabasca Lake basin. 

Because the ancient dimensions and shore con- 
figurations of Lake Athabasca are of great signifi- 
cance in the development of the dune country and 
its vegetation, we venture a tentative reconstruc- 
tion of the Lake McConnell shore lines. Our 
reconstruction is based on a projection of an 
isostatic rebound rate of 38 cm per km (2 ft per mi) 
to the east approximately at right angles to the 
presumed ice margin. East of Old Fort Point the 
shore would have been near the present 305 m 
(1000 ft) contour, south of William Point it may 
have been near the present 335 m (1100 ft) level, 
and at the MacFarlane River near the present 
366 m (1200 ft) level (Figure 5). 

Beaches as high as those projected for Lake 
McConnell have not been found in the Lake 
Athabasca basin. However, Taylor (1960, p. 173) 


'@) 20 40 mi 


0 20 40km 
a | 


Figure 5. Suggested projection of Lake McConnell (Figure 4) into the Lake Athabasca basin when its 
elevation at Buffalo and Faber Lakes was approximately at the present 282 m (925 ft) contour. 
Elevations indicate the approximate present levels. 


stated “Many shorelines occur on the Shield rocks 
north of Lake Athabasca, but even the highest of 
these appears to be no more than 1000-1050 feet 
above sea level.” These elevations came from the 
country around the north angle of the lake, and 
they approximate the elevation we have proposed 
for the southern shore of Lake McConnel south of 
William Point (ca. 330 m or 1100 ft contour). Our 
projection of Lake McConnell into the Athabasca 
Lake basin carries the assumption that higher 
raised beaches will eventually be found above the 
eastern shores of the lake. 

As the glacier receded eastward toward the 
Keewatin Ice Divide (Lee et a/., 1957) the north- 
eastward drainage of rivers such as the Thelon, 


Dubawnt, and Kazan was impounded to form 
lakes. The geography of these lakes, in both space 
and time, has had no more than reconnaissance 
study. Craig & Fyles (1960) summarized knowl- 
edge of them as follows: 

In the western part of Thelon River basin, 
beaches have been found up to about 381 m 
(1250 ft). They become progressively lower east- 
ward to about 214 m (700 ft) at Beverly Lake. A 
proglacial lake in the Dubawnt basin left beaches 
up to about 275 m (900 ft) on the east side of the 
present lake. In the Ennadai Lake - Kasba Lake 
basin the highest beaches have been found at 
about 384 m (1260 ft) above sea level. 


Table |. - Estimated Time Periods for Deglaciation, Postglacial Lakes, the Xerothermic Period, the 
Advance of Forests, and the Occurrence of Aeolian Sand Activity in Northwestern Canada. 


-_ WwW WN 
oS 
SSS 
Suns: 5S 


DEGLACIATION 


Upper Athabasea River valley 
(St-Onge, 1972) 

Tuktoyaktuk Peninsula (Ritchie & Hare, 
1971) 

Restoration of Mackenzie drainage 
(Prest, 1969) 

Athabasca and Great Slave Lakes basins 
ice free (Ibid) 

Last ice in Keewatin (Craig & Fyles, 1960) 


SEQUENCE OF POSTGLACIAL 
LAKES 


Lake Edmonton 

Lake Tyrrell 

Lake McConnell 

Athabasca and Great Slave Lakes 


XEROTHERMIC PERIOD 
(Maximum = M) 

Ritchie & Hare, 1971 
Wright, 1975 
Nichols, 1967b 
Terasme & Craig, 1958 
Lichti-Federovich, 1970 
Sorenson et al. 1971 


YEARS B.P. 
~ 
= =) \O io) ~~ fo) Nn oo WwW N — i@”) 
ete. (vice eS SS Ste er es es, 
= =e 2 ee oe eee 
Sirce tea S (Srcsi' Si Sires? Spies 
oF 


Table |. (Cont’d) - Estimated Time Periods for Deglaciation, Postglacial Lakes, the Xerothermic Period, 
the Advance of Forests, and the Occurrence of Aeolian Sand Activity in Northwestern Canada. 


000rI 
000¢1 
000CI 
OO0T I 


ADVANCE OF INTERFLUVIAL 
FORESTS 


Tuktoyaktuk Peninsula 

Lofty Lake 

Athabasca, Peace, Liard Rivers region 
Athabasca, Cree, Black Lakes region 


ADVANCE OF GALLERY 
FORES FS 


Athabasca, Peace, and Liard Rivers 
region 

Athabasca, Cree, and Black Lakes region 

Thelon River region 

Great Bear Lake and Coppermine River 
region 

Acasta Lake and Snare River region 

Dubawnt and Ennadai Lakes region 


PROBABLE PERIODS OF 
AEOLIAN SAND ACTIVITY 


Interfluves in Athabasca, Peace, and 
Liard Rivers region 

Deltas in Athabasca, Peace, and Liard 
Rivers region 

Athabasca, Cree, and Black Lakes 
region 

Thelon River region 

Great Bear Lake and Coppermine River 
region 

Snowdrift River region 


Deglaciation and Tentative Dating 
of the Postglacial Lakes 


Dates for the formation and drainage of the 
postglacial lakes remain speculative and can give, 
at best, only a general outline for the timing of 
these events (Table |). This outline suggests, 
however, probable limits for some of the time 
periods with which we are concerned. Rates of 
drainage are uncertain because the ice margin was 
stationary for sometime in the lakes above Lake 
McConnell, and because inadequate values for 
isostatic uplift are known. Isostatic uplift is af- 


YEARS BP. 


00001 
0006 
0008 
000S 
000P 
000£ 
000C 
0001 
jUdSIIg 


fected by crustal hinge lines that have not been 
located and studied. 

St-Onge (1972, pp. 12-14) gave a date of 13 500 
years B.P. for samples taken from above the till 
left by the melting glacier. These samples came 
from the uppermost dune area that he described 
along the upper Athabasca River. At about 50 km 
downstream from this point he reported dates 
around 10 000 years B.P. We have no analogous 
early dates for the retreat of ice from the mountain 
fronts in the upper Peace and Liard River valleys. 

Mackay & Mathews (1973) dated floodplain 
sediments in the Mackenzie valley above the 


Ramparts at 11 000-11 500 years B.P., indicating 
that at least the lower part of the valley was open at 
this time. Ritchie & Hare (1971) have given a date 
of 12 900 years B.P. for the first tundra vegetation 
on the Tuktoyaktuk Peninsula just east of the 
Mackenzie River delta. Craig & Fyles (1960) 
concluded from !4C dates available at that time, 
that the Laurentide ice sheet west of Hudson Bay 
could not have survived much later than 7000 
years ago and may have disappeared earlier. 

If the first appearance of tundra vegetation 
marks approximately the beginning of ice retreat 
in the west, the ice front retreated through a 
distance of roughly 1450 km in about 6000 years. 
At this rate it may have reached the western 
margin of the Canadian Shield by about 10 000 
years B.P. and may have cleared the Athabasca 
and Great Slave Lake basins by about 9000 years 
B.P. This agrees with Prest’s estimate (1969) of 
9000 years B.P. for the clearance of Lake Atha- 
basca. 

These dates suggest a time sequence for the 
drainage of Lake Tyrrell down, at least, to the level 
of the uppermost beaches of Lake McConnell 
described by Craig (1965). Assuming that Lake 
Tyrrell, and some phase of Lake Edmonton were 
essentially confluent in the upper Athabasca River 
valley, and using St-Onge’s date from near the 
lower end of his dune area (St-Onge, 1972), a 
tentative date for the beginning of Lake Tyrrell is 
about 10 000 years B.P. Using Prest’s estimate of 
10 000-11 000 years B.P. for the opening of the 
upper Mackenzie River valley, Lake Tyrrell would 
have been rapidly drained down to the level of the 
uppermost beaches of Lake McConnell. Below 
this level its drainage would have been much 
slower as “timed” by the rate of isostatic rebound 
(Craig, 1965). 

The rise of the land surface with respect to the 
lake levels appears to have been relatively slow 
and fairly steady during the last few thousand 
years. Cameron (1922), working at Windy Point 
on Great Slave Lake, counted 100 beaches over 
about 76 m (250 ft) of altitude to the crest of a hill 
where a horsehoe beach was formed as the land 
rose above the lake. He described the beaches as, 
“fairly uniform in depth, and throughout most of 
the rise occur as a series of very regular waves....” 
(Cameron, 1922, p. 353). His description could be 
applied, almost without change, to the raised 
beaches measured by our field party in 1935 at 
Charlot Point, Lake Athabasca, even to the 
horseshoe beach at the top of the hill. Here the 


beaches extend up to about 73 m (240 ft) above the 
lake in a horizontal distance of about 3.8 km 
(2.4 mi), and on a slope of about 6°. 

Higher raised beaches are found around the 
eastern end of Great Slave Lake, up to 165 m 
(540 ft) above the present lake level (Stockwell, 
1933). Blanchet (1926a), who described the Lock- 
hart River valley up to 13 km (8 mi) above its 
mouth at Great Slave Lake, wrote that it had 
carved its channel through 183 m (600 ft) of “sand 
benches to bed rock.” The height and regularity of 
these flights of beaches suggest that they represent 
the higher levels of Lake McConnell, and that they 
might be contemporaneous with those located by 
Craig at 282 m (925 ft) above sea level. If so, this is 
evidence that all of Great Slave was free of ice at 
this time, which we have estimated to be about 
8560 years ago (see below). 

No long series of beaches like those below the 
highest shores of Lake McConnell have yet been 
described anywhere in the Mackenzie drainage 
basin except around Great Bear Lake. Their 
absence from the shores of Lake Peace and the 
higher shores of Lake Tyrrell suggests that these 
lakes were drained so rapidly that storm-built 
beaches could not be formed except during still- 
stands of the lake levels. Large deltaic deposits 
such as those in the Peace River valley indicate 
that such still-stands occurred, but their timing is 
obscure. Lake deposits that probably were formed 
in Lake Tyrrell were reported by Ells (1932) at an 
elevation of 427 m (1400 ft), or perhaps over 460 m 
(1500 ft), on the northeastern face of the Muskeg 
Hills. When these formed, the ice edge was at least 
80 km (50 mi) northeast of McMurray (Taylor, 
1960). It is also possible that the deposit represents 
one of the still-stands in the earlier drainage of 
Lake Tyrrell. Without more data on the rate and 
timing of isostatic rebound in this area this still- 
stand cannot be correlated with the deltaic features 
in the Peace River valley or elsewhere. 

Noble (1971, p. 105, and pers. comm.) described 
an early Indian culture, called “Acasta Lake”, in 
the region around the west shore of the north arm 
of Great Slave Lake, “...and thence northward, 
east of Great Bear Lake to within 70 miles of the 
arctic coast.” A '4C date of 7000 years B.P. was 
based on samples of charcoal from hearths used by 
people whose artifacts indicate that they were 
primarily forest dwellers. In this region, the evi- 
dence of culture was found at 14 sites on sand 
eskers or blowouts at elevations ranging from 259 
to 427 m (850 to 1400 ft) above sea level. Noble 


suggested that these people came into the area 
from the upper Mackenzie valley via the north- 
west shore of Great Slave Lake which, following 
Craig’s interpretation (1965), would be Lake 
McConnell. There appears to be some cultural 
similarity between the Acasta Lake people and 
those represented by Millar’s excavations near 
Fort Liard dated about 8700 years B.P. (Millar, 
1968). These people probably travelled and camp- 
ed on riverbanks and lakeshores where water and 
fishing were readily accessible, as do modern 
Indians in that country. The habit of camping on 
sand or gravel beaches around the eastern arm of 
Great Slave Lake was used by Noble (1971) asa 
way to check the chronology of the later cultural 
sequence for the region. This sequence was based 
on the study and comparison of archaeological 
sites, many of them having '4C dates extending to 
the early 19th Century. The dates showed a regular 
progression from the oldest on the higher raised 
beaches to the most recent near the present level of 
Great Slave Lake. 

The location of the lowest Acasta Lake site 
(259 m or 850 ft) is near the end of the North Arm 
of Great Slave Lake, at Mosquito Creek, just 
southwest of Frank Channel. It is about 80 km (50 
mi) due south of the 282 m (925 ft) shoreline of 
Lake McConnell, located near Faber Lake by 
Craig (1965). About 7000 years ago it is probable 
that the Acasta Lake people traveled and camped 
on beaches that were then on a shore of the lake 
that was about 23 m (75 ft) below the uppermost 
shores noted by Craig. As the land continued to 
rise, later cultures used lower beaches as they were 
progressively formed and raised. If this concept is 
valid we may have materials with which to date the 
highest shores of Lake McConnell. 

The rise of the land with respect to the lake level 
has been about 103 m (337 ft) in 7000 years (using 
156 m (513 ft) as the present elevation of the lake). 
This gives an average rate of rise of about 1.5 mor 
4.8 ft per century. Using this rate for the additional 
23 m (75 ft) to the highest shores of Lake 
McConnell, the additional rise would have taken 
about 1560 years. Thus we have a tentative date 
for the beginning of Lake McConnell at about 
8560 years B.P. 

The proposed average rate of rise can also be 
used to approximate the time at which the Fort 
Smith escarpment became exposed and separated 
Lake McConnell into two lakes — Athabasca and 
Great Slave. The escarpment is now at about 
205 m (675 ft) above sea level, so that at the highest 


12 


level of Lake McConnell it would have been 
submerged about 76 m (250 ft). If the land rose at 
about 1.5 m or 4.8 ft per century, and if 8560 years 
B.P. is the approximate time of the formation of 
Lake McConnell, the escarpment would have 
emerged about 3350 years ago. 

Again using 8560 years B.P. for the establish- 
ment of Lake McConnell, the propable upper and 
lower limits of Lake Tyrrell (534 m (1750 ft) and 
282 m (925 ft) respectively), and the earliest date 
for Lake Tyrrell (ca. 10 000 years B.P.), then Lake 
Tyrrell would have been drained to the upper level 
of Lake McConnell (250 m or 825 ft) in about 1440 
years. This gives an average rate of about 17.4 m 
(57 ft) per century. This cannot bea realistic figure 
because the time spans of at least two still-stands 
during which about 590 and 1150 km? (228 and 
452 sq mi) of sandy aeolian and alluvial materials 
were accumulated in the Peace River Valley are 
unknown (Taylor, 1960). Therefore when the lake 
fell it went down far more rapidly than the average 
rate might indicate. 

The available '4C dates indicate that lakes 
formed in the basins of the Kazan, Dubawnt, 
Thelon, and Back Rivers were of relatively short 
duration. Craig (1959a, p. 510) from study of 
organic remains in a pingo in the Thelon basin 
(Lat. 64°17’, Long. 102°41’), concluded that the 
ice had left the site of the pingo “considerably 
more than 5500 years ago”, long enough for the 
continental ice sheet to disappear, or to retreat to 
the ice divide and allow the proglacial lake to 
drain. Sorenson et al. (1971) found evidence that 
trees had reached north Ennadai Lake as early as 
about 6000 years ago, and Dubawnt Lake about 
4000 years ago. It is possible that the proglacial 
lake in the Dubawnt basin was connected with 
that in the Thelon (Craig & Fyles, 1960, p. 8), at 
least in its early stages, and may have been drained 
as early. 


Physiography of the Sandstone Areas 
South of Lake Athabasca 


Tyrrell & Dowling (1897) described the region 
south of Lake Athabasca, underlain by Athabasca 
Sandstone, as a wide sandy plain, sloping gently 
downward to the north. Sproule (1939), using 
aerial photographs for reconnaissance, confirmed 
the plain-like character of the landscape. He 
mapped the southern boundary of the Athabasca 
Sandstone at about 208 km south of William 


Point, Lake Athabasca. Recent contour maps 
(Energy, Mines and Resources Canada, 1:250 000, 
Sheets 74N, 74K, 74F) give the altitude of this 
point on the boundary at about 418 m above sea 
level. Thus, the general slope of the surface is 
about 98 cm per km. The sandstone beds are 
generally flat-lying though Blake (1956) reported 
some minor folding near Lake Athabasca. The 
weathering and glacial scouring of the sandstone 
appear to have produced most of the sand we see 
in the lake beaches and dune areas. Most of the 
local topography is formed of sandy glacial de- 
posits variously reworked by wind and water. 

Dowling ascended William River from its 
mouth at Lake Athabasca (Tyrrell & Dowling, 
1897) and encountered the first rapids, composed 
of low sandstones ledges, about 19 km (12 mi) 
above the mouth of the river. He noted one fall of 
about |.5 m(5 ft) and stated that the river fell only 
about 14.6 m (48 ft) in the 48 km (30 mi) that he 
travelled. Blake (1956), who descended William 
River, reported passing seventy-five rapids, most 
of which he associated with the passage of the river 
through morainic deposits. The sandy glacial drift 
is in the form of broad, gently rolling plains 
covered with jack pine or wide expanses of marsh 
and muskeg. Drumlins and eskers or elongated 
ridges are commen, both are composed primarily 
of sand. 

Tyrrell (Tyrrell & Dowling, 1897, p. 23D) 
described, in this region, a kind of morainic 
deposit which he considered distinctive: 

“The most conspicuous and interesting drift 
hills in the whole region, however, occur in the 
basin of Cree Lake, around Black Lake and onthe 
banks of Stone River. They are steep, narrow 
ridges, parallel to the direction of glaciation, with 
the sides joining in a crest that may be less than a 
yard in width. They average from a quarter of a 
mile to one mile in length, and round down gently 
to both ends, with a characteristic drumlin-like 
contour, and vary from 70 to 250 feet in height, the 
average being about 120 feet. Unlike eskers, or 
kames, which they resemble in some respect, they 
are not composed of assorted material, but rather 
of unassorted rock-flour mixed with boulders. 
Unlike drumlins, they do not seem to have been 
ever compacted or overridden by the ice, as the 
material is loose, and the summit is not rounded 
off from side to side, but rather from the crest 
downwards, they descend in as steep a slope as the 
material will stand at. Further, they all lie in the 
basins of large post-glacial lakes, the principal 


ones examined being in Hyper-Cree and Hyper- 
Black Lakes. As they seem to differ from any drift 
hills that have been definitely described, I would 
suggest for them the name ispatinow, the Cree 
word for a conspicuous hill.” 

He suggested that these “ispatinows” were form- 
ed in: “narrow gorges in the ice-sheet, when the 
front of the glacier was bounded by a deep lake. 
Streams flowing on or near the surface plunged 
into these ice-bound gorges and carried their load 
of detritus into the quiet water at the bottom of the 
gorge.” He thought that the material would then 
remain unsorted. In more recent literature the 
ispatinows have been treated as elongated sandy 
drumlins (Flint, 1947, pp. 124-125; Charlesworth, 
1957, pp. 390-423). The manner of their for- 
mation, however, is uncertain. 

In his ascent of William River, Dowling (Tyrrell 
& Dowling, 1897, p. 70) described: “A boulder 
ridge, which seems to be beneath and protruding 
through the sands, crosses the river about nineteen 
miles above its mouth. The ridge is made up of 
more rounded material, and seems to be a con- 
tinuation of a high ridge or series of long hills 
which lie to the east called the Fish Mountains. 
These hills are probably of the same character as 
the ispatinows around Cree and Black Lakes. 
Above the ridge the surface is more even and 
covered with a small growth of Banksian pine.” It 
is presumed that Dowling’s 31 km (19 mi) was 
measured along the river, and if so the ridge is 
about 4 km (2.5 mi) above the large William River 
dune area, at an altitude of about 275 m (900 ft) 
above sea level, and (according to the recent 
topographic map) situated in a broad sand plain 
partially covered with pine. Dowling (Tyrrell & 
Dowling, 1897, p. 70D) mentioned the “Fish 
Mountains” in one other place, at Beaver Point, 
where he said: “The country behind rises more 
abruptly. The Fish Mountains or Hills are seen as 
a wooded ridge 200 feet high above five miles 
inland, and are the edge of a higher plateau which 
gradually approaches the lake shore.” Here he was 
looking across the Thomson Bay sand dunes 
which extend up to hills that are at 305-335 m 
(1000-1100 ft) above sea level. 

The ridge mentioned by Dowling along William 
River was not seen by our field parties, but the hills 
south of Thomson Bay were examined in 1975. 
Close to the southern edge of the dunes is a 
prominent ridge made up of unsorted boulders, 
stones, and sand (Figure 26). About | km south 
of Little Gull Lake is another, more discon- 


tinuous, east-west ridge located on a plain that 
rises only slightly to the south (Figure 6). It, 
also, is of unsorted coarse materials and sand. 

East-west ridges of similar nature were exami- 
ned by one of our field parties about 3 km south of 
the lake shore and about 8 km southeast of 
Wolverine Point. These ridges (Figure 14) are 
relatively straight for considerable distances, ge- 
generally parallel, but ocxcasionally forked and 
anastamosing. Many are discontinous and form 
series of ridge-like, variously separated, hills. The 
area lies between the 244 and 275 m contours, and 
the ridges are 9 to 12 m high with rather sharp 
summits. 

In their orientation and altitudes the ridges near 
Lake Athabasca resemble the “ispatinows” of 
Tyrrell. They were almost certainly covered by a 
proglacial lake and have been greatly modified by 
wind and shore processes. These elongated ridges 
are important in the present context because they 
have a high content of sand which can be moved 
easily by wind or water. 


No well-defined recessional moraines have yet 
been found on the area underlain by the Athabas- 
ca Sandstone. Sproule (1939) mapped a moraine 
to the southward and westward, extending from 
east of the Mudyatik River northwestward via the 
headwaters of the Gwillim River, Black Birch 
Lake, the upper Clearwater River, Lloyd, and 
Patterson Lakes. Small, parallel ridges northwest 
of Patterson Lake were considered recessional 
moraines. All of these are outside the south and 
southwest borders of the sandstone (Sproule, 
1939; Blake, 1956). 

In view of the preceeding suggested history of 
the sandstone region south of Lake Athabasca we 
propose that most of this region originated not as 
dry land exposed by withdrawal of glacial ice but 
rather as the predominantly sandy bottom of 
Lakes Tyrrell and McConnell. The former was 
drained relatively rapidly to form pronounced 
shoreline beaches only during still-stands of un- 
known duration down to about the upper level of 
Lake McConnell. At this level it might be called 


Figure 6. Elongated ridge south of Little Gull Lake. The young jack pine seedlings, 6-11 years old, on the 
sand plain germinated after a burn. 


] 


“ancestral Lake Athabasca,” with its southern 
shore extending eastward to the MacFarlane 
River and ranging from approximately the present 
305 m (1000 ft) contour up to about the present 
366 m (1200 ft) contour. It may have reached this 
level about 8560 years ago and possibly earlier. 
Since then, the rate of lowering has been much 
slower and more steady. The earlier drainage (251 
m or 825 ft) may have lasted about 1440 years, 
while the later drainage (126 m or 414 ft) took 
about 8560 years. 

It can be assumed that south of Lake Athabasca 
there is a series of beaches corresponding to those 
on the north side of the lake at Charlot Point. 
Judging by those recently formed on the present 
south shore, they are largely of sand, greatly 
accentuated by wave action and ice-push, and 
spaced at wide or narrow intervals depending 
upon the configuration of the shores along which 
they were formed and upon the position of these 
shores on a lake that was larger and stood at 
higher levels. They are probably highly altered in 
form by wind. 

The best evidence we have of the nature of the 
surfaces thus exposed is the presence of ventifacts 
and sand polished cobbles and boulders in areas 
now stabilized by forest vegetation. Tremblay 
(1961) described this in an area between latitude 
56° and 58°N, and between longitude 108° and 
111°W. The localities studied are near Frobisher 
Lake in Saskatchewan and along the Marguerite 
River in northeastern Alberta. From Tremblay’s 
description, they closely resemble the ventifacts 
we have found among the Lake Athabasca dunes 
and on forested sandy areas nearby. They presu- 
mably formed when there was not enough vegeta- 
tion to obstruct the wind. The wind direction is 
shown by the orientation of the striation and 
fluting on bedrock. Both areas studied are outside 
the Athabasca Sandstone, but very near its south- 
western boundary at altitudes over 488 m (1600 ft) 
above sea level. Tremblay (1961, p. 1563) stated: 
“These erosional features and some of the sand 
deposits in the form of dunes, sheets, and ridges, 
not described here, suggest that the area was a 
huge desert during or soon after the deglaciation, 
that the sand could move readily under the action 
of wind, that the vegetation cover was practically 
nonexistent, and that during a fairly long period 
there were strong winds blowing predominantly 
from southeast to northwest (ca. N. 35°W).” 

In the area studied by Sproule (1939) he 
mapped, largely from aerial photographs, a great 


many long ridges generally trending at right angles 
to the northeast to southwest direction of ice 
advance. He described them (p. 104) as “narrow, 
generally sharp, ridges of sandy moraine... They 
pass over bare rock, and through muskeg, over 
hills and valleys, and are not deflected by surface 
irregularities. They vary up to three miles or more 
in length. The base width is seldom over 100 
yards.... The highest measured was 35 feet. In 
most cases they are parallel to one another, 
although occasionally separate sets converge at 
acute angles.” He believed them to be “ice-crack” 
moraines, formed in transverse cracks near the 
margins of receding glaciers. 

David (1981) has recently studied much the 
same area seen by Sproule, but has greatly expan- 
ded the known occurrence of the long ridges, 
which he believes to be attenuated parabolic sand 
dunes. He mapped them as occurring not only 
beyond the sandstone area, but also well within it. 
He confirms the widespread presence of ventifacts 
and the southeasterly paleo-wind direction noted 
by Tremblay (1961). By studying the mean orien- 
tations of some 356 dunes over a distance of 275 
km he found that their general southeast to 
northwest orientation gradually veered eastward 
about 9°. This suggested that the dune-forming 
southeast winds had had a curved trajectory, 
blowing clockwise around a center that lay to the 
eastward. He proposed that this center was in a 
high pressure system over what remained of the 
Laurentide ice sheet. 

David (1981, p. 307) proposed that “dune 
activity in the Cree Lake region began perhaps 
around 10000 years BP and lasted till about 8800 
years ago” when the ice sheet had melted back far 
enough to greatly reduce the effects of winds from 
its high pressure system. He noted that the dunes 
are progressively less well developed eastward 
toward the MacFarlane and Cree Rivers, indicat- 
ing gradual abatement of the winds. He thinks that 
by 8800 years ago the westerly, northwesterly, and 
northeasterly anticyclonic winds began to prevail. 
The date he has chosen for this change, 8800 B.P.., 
is very close to the one we are suggesting (8560 
B.P.) for the formation of Lake McConnell and 
the beginning of the slower and more steady rate 
of lake drainage by differential isostatic rebound. 
Also it probably dates the beginning of the present 
dune fields. 

We are not able to judge whether Sproule or 
David is correct about the origins of these ridges; 
and if they are dunes, whether they may properly 


be called parabolic dunes. In whatever way they 
are rationalized, they provide clear evidence that 
plant habitats of actively windblown sand proba- 
bly have been widespread over one or another part 
of the Athabasca Sandstone area for at least 9000 
years. 


Geographic Distribution and Extent of 
Aeolian Sand in Northern Saskatchewan 
and Alberta and in the Continental 
Northwest Territories 


Materials in this chapter are derived from our 
own field experience and from descriptions found 
in the exploration literature of the last two 
centuries. These descriptions will not be repeated 
here, but they may be found in the papers cited 
below. Notes extracted from them may be placed 
in four nonexclusive categories. 

Sand plains — more or less level or gently rolling 

surfaces underlain by sand. 

Sand hills or ridges — topography of sand not 
differentiated as having the forms of dunes, 
eskers, or drumlins. 

Sand dunes — topographic forms clearly recogni- 
zed as dunes. 

Sandy eskers or drumlins — sandy ridges having 
the form and orientation of eskers or drum- 
lins and recognized as such by the observers. 

The following references are arranged in five 
geographic regions. 

(1) Sand deposits in the drainages of the Atha- 
basca, Peace, Buffalo, Hay, and Liard Rivers. 

Allan & Carr (1946); Bayrock & Root (1972); 
Beach & Spivak (1943); Cameron (1922); Craig 
(1959a, 1959b, 1960, 1965); Craig & Fyles (1960); 
Day (1966, 1968); Hage (1944); Lindsay er al. 
(1958a, 1958b, 1960); Odynsky & Newton (1950). 
Odynsky et al. (1952, 1956); Rutherford (1930); 
St-Onge (1972); Taylor (1956, 1960); Williams 
(1922). 

(2) Sand deposits bounded north by Athabasca 
and Black Lakes, west and south by the margin of 
the Canadian Shield, and extending eastward to 
Wollaston and Cree Lakes, Cree and Mujatik 
Rivers. 

Alcock (1936); Blake (1956); Fahrig (1961); 
R. Green (pers. comm.); Sproule (1939); Tremblay 
(1961); Tyrrell & Dowling (1897); David (1981). 

(3) Sand deposits between Lake Athabasca and 
the eastern arm of Great Slave Lake. 

Blanchet (1926b); Camsell (1916); Wilson (1939). 


(4) Sand deposits in the country between Great 
Slave and Great Bear Lakes. 

Noble (1971, 1974); Preble (1908); Stockwell 
(1933); Thieret (1964). 

(5) Sand deposits in the region northeast and 
east of Great Slave and Great Bear Lakes, includ- 
ing the drainage basins of the Kazan, Dubawnt, 
Thelon, Lockhart, Back, and Coppermine Rivers. 

Anderson (1940-41); Back (1836); Bell (1901); 
Bird (1951); Blanchet (1926a, 1930); Craig & Fyles 
(1960); Hanbury (1904); Harp (1961); Hearne 
(1796); Kidd (1932, 1933); McDonald (1926); 
Porsild (1929); Richardson (1823); Taylor (1960); 
Tyrrell (1898); Wilson (1939, 1945). 

The places of nearly all observations recorded in 
the above literature can be located with fair 
precision on a modern map. When this is done, a 
pattern for the distribution of aeolian sand beco- 
mes apparent although there are large areas that 
are relatively unexplored. 

A major boundary follows the north northwest 
— south southeast trend of the division between the 
Canadian Shield and the softer rocks that lie west 
of it. In the west the glacial drift is relatively fine 
textured and is derived mainly from Paleozoic or 
Cretaceous shale, gypsum, and limestone. Aeolian 
sands are confined mainly to deltaic deposits in the 
broad valleys of the larger streams. 

East of the boundary, on the harder rocks of the 
Canadian Shield, the drift is mainly of sand and 
gravel with far more boulders. Where the surface 
rock is granite, gneiss, or of crystalline, highly 
metamorphosed Archaean sedimentary rocks, the 
drift is thin, bouldery, and gravelly. Where the 
surface rock is sandstone the drift is mainly of 
sand and is usually much thicker. This contrast 
was noted by Sproule (1939) in the country west of 
Cree Lake, and by Wilson (1939) northeast of 
Great Slave Lake. 

The major areas of aeolian sand in the Canadian 
Shield portion of the region are the areas where 
the drift is directly underlain by sandstone. A map 
of the aeolian sands made from the sources listed 
above is generally coincident with Fahrig’s map 
(1961) showing the distribution of sandstone 
(Figure 2, with modification). The movement of 
the Keewatin ice sheet was toward the west and the 
sandy drift was transported in this direction from 
its sandstone sources. Hence the western borders 
of the aeolian sands extend beyond the borders of 
the sandstone areas. This was noted by Wilson 
(1939) when he found the sands northeast of Great 
Slave Lake to be progressively thicker eastward 


toward the sandstone areas of the Thelon basin. It 
was also seen by Tremblay, (1961), Sproule (1939), 
and David (1981) who saw dune topography, 
ventifacts, and wind-cut rock outcrops beyond the 
western border of the sandstone south of Lake 
Athabasca. 

From Bird’s map and descriptions we estimate 
that at least 50 percent of his area has very sandy 
drift which has been or is now being reworked by 
wind. Sproule’s map and photographs, as well as 
his text, indicate that at least the southern part of 
the Athabasca Sandstone area is a sandy plain 
whose relief is mainly formed by eskers and 
drumlins that are also made up primarily of sand. 
Blake’s notes (1956) corroborate this and carry it 
northward to Lake Athabasca. In view of Tyrrell’s 
descriptions of the region of Cree River and Black 
Lake, it seems reasonable to assume that at least 
80 percent of the Athabasca Sandstone area may 
have gone through a period of intense aeolian 
activity. Sandstone underlies only a part of 
Taylor’s map area but his notes on the nature of 
the drift suggest that about 60 percent of his area is 
or has been subjected to reworking of sand by 
winds. An estimate for Wilson’s map areas (1939, 
1945) has to be based largely on observations by 
earlier students. All the eskers he mapped were 
believed to be of sand. Blanchet’s description of a 
great sand plain between Artillery and Ptarmigan 
Lakes (1924-1925) suggested that even in the 
western parts of Wilson’s map areas there are large 
tracts of sand, exclusive of the eskers, that have 


been reworked by wind. We estimate that at least 
75 percent of his map areas may be so classified. 

An estimate of the total area of windblown sand 
in the region is bound to be speculative. The 
figures given below are conservative and tend to be 
under-estimates rather than over-estimates. The 
most reliable data are for the deltaic deposits in the 
valleys of the major rivers west of the Canadian 
Shield — the Athabasca, Peace, Slave, Liard, and 
upper Mackenzie Rivers. They are based on soil or 
hydrographic survey maps by Day (1966, 1968), 
Lindsay et al. (1958a, 1958b, 1960), Bayrock & 
Root (1972), and on St-Onge’s (1972) maps of 
postglacial lakes in the upper Athabasca basin. 
Together they total approximately 20453 km?. In 
the Canadian Shield portion of the region the total 
area of the mapped surface deposits of sandstone 
is estimated roughly at 209062 km?. 

We have four maps on which glacial features are 
given in some detail, two located mainly in sand- 
stone areas and two on areas marginal to the 
sandstone. Bird (1951) mapped about 53075 km? 
in the Thelon River sandstone region and Sproule 
(1939) about 13986 km? around Cree Lake and 
northwest of it. Wilson’s maps of eskers (1939, 
1945) cover about 89870 km? in the Lockhart 
basin and eastward to the upper Thelon. Taylor’s 
(1956) map of a portion of the Middle Back River 
comprises about 16316 km?. 

The above estimates do not do justice to large 
areas of sandstone, such as those along the Arctic 
coast and along the Snowdrift River, for which we 


Table 2 — Distribution of Sand and Aeolian Activity in Northern Saskatchewan and Alberta and 
in the Continental Northwest Territories 


Cree, Athabasca, Black Lakes region 

Thelon River region 

Arctic Coast region 

Snowdrift River region 

Esker region NE of Great Slave L. (Wilson) 
Middle Back River region (Taylor) 
Athabasca and Peace River region 

Slave, Liard, and Upper Mackenzie R. region 


TOTALS 


Probable area 


Probable percent subject to 
of area subject postglacial aeolian 

Total area to aeolian activity in 
in km? activity km? 
71 900 80 57 520 
64 800 50 32 400 
66 000 50 33 000 
6500 50 3250 
90 000 75 67 500 
16 400 60 9840 
20 500 100 20 500 
2100 100 2100 
338 200 226 110 


have inadequate information. Furthermore, the 
50 percent figure we are using for these and the 
large Thelon area based on the “sample” provided 
by Bird, is probably much too low. Table 2 is a 
summary of the above estimates. 


The Advance of Forests and the Post- 
glacial Xerothermic Period 


Stabilization of aeolian sand in our region is 
accomplished by the development of vegetative 
cover, the most effective being forest and muskeg. 
Both the advent of vegetation and the movement 
of the sand have, in turn, been conditioned by the 
postglacial warm-dry, or xerothermic period 
(called by some authors the “hypsithermal” period). 


The Trees 


The poplars were the first trees to move into the 
western interior of Canada (Lichi-Federovich, 
1970) and into the subarctic (Ritchie, 1977). The 


poplar woodland, however, formed a very short 
phase immediately preceding the invasion of spru- 
ce (Ritchie & Yarranton, 1978). White spruce 
(Picea glauca) 1s, primarily, a tree of medium to 
well drained soils, while the black spruce (P. 
mariana) 1s most characteristic of poorly drained 
soils such as develop on muskegs or over heavy 
clays. These are by far the most abundant trees in 
the boreal American forests. Less abundant, and 
of less continuous distribution are tamarack (Larix 
laricina) and white birch ( Betula papyrifera), both 
of which are sometimes found with the spruces at 
or near the arctic tree line. Somewhat more 
southern in the boreal forest are the pines (Pinus 
contorta and P. banksiana), balsam poplar ( Popu- 
lus balsamifera), trembling aspen (P. tremuloides), 
and the firs (Abies lasiocarpa (Hook.) Nutt. and 
A. balsamea (L.) Mill.). 

The white spruce, Picea glauca (s.1.) now ranges 
throughout the boreal American forest, from 
Newfoundland to western Alaska and southward 
into northern New England, and the northern 
Cordillera. The black spruce, Picea mariana, also 


Figure 7. Beach ridge on the Lake Athabasca shore. Picea glauca var. albertiana is the primary tree on the 
ridge and E/ymus mollis appears on the beach dune. 


has a wide trans-continental range but it differs 
somewhat from that of P. glauca. In the Appala- 
chian Mountains it reaches considerably farther 
south than the latter, and in interior Alaska, 
central and southern Yukon, and in southwestern 
Mackenzie there appears to be a large area in 
which it occurs sparingly or not at all (Hultén, 
1968, p. 62). There is an area around Kluane Lake 
in southwestern Yukon where it is not found, and 
where its place in the muskegs is occupied by the 
ubiquitous white spruce. 

These species probably had similar ranges in 
pre-Wisconsin time, and perhaps in earlier inter- 
glacials. During long periods they had large, 
continuous populations. In white spruce there 
developed regional ecotypes that were genetically 
segregated and were adjusted to major habitat 
complexes (LaRoi & Dugle, 1968). These habitats 
varied from south to north and from east to west. 
Strains were developed in the northern Rocky and 
Mackenzie Mountains and in Alaska adjusted to 
the subarctic-montane conditions of those re- 


gions. In both the western and eastern segments 
there probably were “clines” of ecotypes ranging 
from those adjusted to subarctic habitats to those 
living in more temperate regions. The occurrence, 
in P. glauca, of photoperiodic ecotypes that 
evolved as adaptations to northern climates (sea- 
sonally changing environments) was demon- 
strated by Vaartaja (1959). 

The black spruce appears to be remarkably 
uniform taxonomically throughout its wide range. 
No morphological subdivisions such as occur 
among the white spruces (see below) have ever 
been defined. There seems no doubt, however, 
that its population has contained ecotypic varia- 
tions analogous to those in the white spruce and of 
many other common species. 

The major effect of the Wisconsin glaciation 
upon these patterns appears to have been the 
destruction of major parts of them (Hultén, 1937). 
The ice completely separated the continent-wide, 
continuous populations into eastern and western 
segments, and at the same time reduced the 


os 
~ 


Figure 8. The columnar habit of Picea glauca var. albertiana as shown by trees growing near treeline at 
Fairchild Point, Great Slave Lake, N.W.T. 


segments to smaller or larger fractions of their 
former extent. The remains of the northwestern 
populations are thought to have lived through the 
Wisconsin glaciation in central Alaska, or in the 
eastern foothills of the Rocky and Mackenzie 
Mountains and perhaps in the Richardson Moun- 
tains. The eastern and central segments were 
reduced to scattered populations south and south- 
east of the ice. Subarctic ecotypes that formerly 
ranged through the northern parts of the eastern 
populations must have been nearly or quite com- 
pletely eliminated, leaving only the ecotypes that 
were adjusted to life at or near the southern 
borders of the former range of the species. 

Trees coming into our region after the Laurenti- 
de ice receded, therefore, are believed to have 
migrated from these remnant populations (Hultén, 
1937; Halliday & Brown, 1943; Raup, 1930, 1946). 

The most common white spruce in northwest- 
ern Canada north of about the 60th parallel is var. 
albertiana?, a tree with a narrowly pyramidal or 
columnar crown (Figures 7 & 8) and cones that 
are shorter and broader than those of the eastern 
white spruce. 

Hultén (1968, p. 61) stated that var. albertiana 
replaces the typical eastern P. glauca var. glauca 
“from Keewatin and northern Saskatchewan 
west. The late A: E.. Porsild (pers: comm.) 
pointed out that part of this replacement is made 
by another segregate of P. glauca, var. porsildii, a 
tree that resembles the eastern white spruce in 
form but is readily distinguished by relatively 
smooth bark that has resin blisters like those on 
the balsam fir. It is common in the Mackenzie 
valley and extends westward through Yukon to 
central Alaska. Some of the white spruce in the 
southern part of the Mackenzie drainage basin, 
northward to the lower valleys of the Athabasca 
and Peace Rivers and along the upper Slave River 
are more broadly pyramidal than var. albertiana 
and may represent the typical P. glauca of the 
eastern boreal forests. 

The white spruce appears to have been the 
principal coniferous tree in the advance of forests 
in northwestern Canada and Alaska following the 
retreat of the last glacial ice. It is the tree of most of 
the arctic timberline in this region and probably 


?The name var. a/bertiana may not be available for this 
common tree if it is proved to be based ona hybrid between P. 
glauca and P. engelmannii Parry as suggested by Taylor 
(1959), Horton (1959), and Roche (1969). 


20 


was the first to reach it. The following discussion, 
therefore, will be concerned mainly with this 
species. 


The Probable Pattern and 
Chronology of Advance 


A general pattern for the advance of forest into 
the glaciated region probably was the same as that 
we see now at boundaries between major types of 
vegetation. Such boundaries usually form a den- 
dritic pattern that follows that of the drainage 
systems that cross the boundary. The largest 
example we have of this is the boundary between 
the deciduous forests of the Mississippi valley and 
the grasslandof the Great Plains. The streams are 
bordered by forest for hundreds of kilometers to 
the westward, while the interfluves are open 
grassland. The long westward extensions of trees 
are called “gallery forests.” The arctic timberline 
has the same general pattern. Such gallery forests 
form projections into the tundra in the valleys of 
the major streams. The longest extensions are in 
the streams flowing northeast or north: the 
Thelon, Coppermine, and Mackenzie Rivers. 
Shorter ones extend upstream from the large 
lakes: the Snare and Dease Rivers are examples. 
The Back River has no gallery forest, for it rises in 
the tundra. 

Using the above sketch, it is possible to outline a 
probable history for the advance of forest into our 
region (Table 1). Before the advent of the Pleisto- 
cene glaciation, the great rivers from the western 
mountains, the Athabasca, Peace, and Liard, had 
already carved deep valleys in the adjacent High 
Plains. These valleys broadened outward as the 
plains lowered to the east and were separated by 
wide interfluves with gently rolling surfaces. As 
the glacial ice receded and the postglacial lakes 
were drained, these plains probably became covered 
rapidly with some form of tundra or grassland, or 
some combination of the two. Drainage of the 
plains probably was imperfect, so that both wet 
and dry grassland or tundra sites were widespread. 
Probably dry sites were relatively more prevalent 
than would be the case today because of the 
developing xerothermic climate. It is probable 
that trees came into the delta region of the 
Mackenzie River and into its lower valley fully as 
early as those in the upper Peace and Athabasca 
valleys or perhaps earlier, coming from the eastern 
slopes of the Mackenzie and Richardson Moun- 
tains. Trees from the eastern remnants of the 


boreal forest apparently reached the southern part 
of the Mackenzie basin somewhat later, possibly 
via the Churchill River valley. 

A tentative chronology for the advance of forest 
into our region can be approximated from the !4C 
dates that are available. The principal sources for 
these dates are in reports of palynological and 
archaeological research. Ritchie (1972, 1977) and 
Ritchie & Lichti-Federovich (1967, 1968) have 
described the hazards attendant upon the interpre- 
tation of pollen stratigraphy in the Arctic and 
Subarctic, especially in the absence of macrofossil 
material. This is due to several causes, not the least 
of which is long-distance aerial transport of 
pollen. They cite the case of the current pollen rain 
at Resolute on Cornwallis Island in the Arctic 
Archipelago, where 60% is composed of Picea, 
Pinus, Betula, Populus, Juniperus, Alnus, and 
Ambrosiae, all of which had been transported at 
least 1500 km. In our use of '4C dates, therefore, 
we have depended mainly on those supplied from 
macrofossils. 

Our conception of the late- and postglacial 
history of the spruce forests raises several ques- 
tions that should be dealt with before any elabora- 
tion is attempted. Is there clear evidence that white 
spruce survived the last ice advance in the refugia 
mentioned above? If so, were the surviving popu- 
lations large and varied enough to have main- 
tained their habitat versatility? Was there an ice- 
free corridor of sufficient continuity in the eastern 
foothills of the Rocky, Mackenzie, and Richard- 
son Mountains to have harbored such a popula- 
tion? 

Hultén (1937) considered the Yukon valley in 
Alaska a viable refuge for a large area of boreal 
forest during the Wisconsin glaciation. Hopkins 
(1972) attests to its being unglaciated, but restricts 
the spruce refuge to a relatively small area near the 
mouth of the Yukon River (pp. 136-137). Although 
the temperature climate he proposes for the period 
would have permitted forests farther east, he 
thinks lack of moisture would have precluded 
them. He proposes that central Alaska got its 
present spruce from the small lower Yukon refuge 
and from south of the Laurentide ice sheet in 
Montana and Alberta (p. 141), presumably by way 
of the Mackenzie valley. 

The assumption that spruce bordered the last 
ice in Montana and Alberta is of longstanding. 
The ice in this area presumably had encroached on 
the grassland of the Great Plains, with spruce 
migrating ahead of it to become the remnant 


21 


population from which it later migrated north- 
ward to the lower Mackenzie valley and thence to 
central Alaska, a distance of at least 3200 km. 
Whether such a refugium actually existed in 
Alberta and Montana has been questioned (Raup, 
1946, pp. 77-78), but if it did it probably would have 
consisted of spruce containing only southern 
ecotypes incapable of that long expansion to the 
arctic coast. An analogous situation may be that 
of the small spruce population placed by Hopkins 
near the mouth of the Yukon. If the interglacial 
forests of central Alaska were completely elimi- 
nated during the last glaciation, the remnant on 
the more humid west coast may not have been 
versatile enough to move into the drier interior as 
rapidly as Hopkins suggests. 

The preceding notes suggest that the most likely 
source for the postglacial spruce in our region is 
in the northern Cordillera, probably in the eastern 
valleys and foothills. Much turns upon whether 
there actually was a “corridor”, in the Mackenzie 
River region between Cordilleran and Laurentide 
ice during the last glacial maximum. Many archaeo- 
logists have assumed or hoped that there was, for 
it would provide a much-needed late glacial route 
by which people coming through northern Beringia 
could reach the northern Great Plains. But many 
geologists have been loath to accept sucha corridor, 
and argument over it still goes on. 

There seems to be no question that the 
Mackenzie River was stopped during the last ice 
advance. Otherwise the great proglacial lakes 
could not have been formed in the central part 
of the basin. It also seems clear that the ice 
receded first from the Mackenzie delta region and 
the lower Mackenzie valley (Craig, 1965.) 

According to Prest (1969) the ice began to leave 
the delta region 13 500-14 000 years ago. Ritchie 
& Hare (1971) presented evidence that the first 
tundra vegetation appeared on the Tuktoyaktuk 
Peninsula, just east of the mouth of the 
Mackenzie, about 12900 years ago, and that 
spruce came about 11500 years ago, forming an 
open forest-tundra vegetation. Ritchie (1977), 
working on the Campbell-Dolomite uplands near 
Inuvik on the east side of the delta, found that 
poplar appeared about 10300 years B.P. and 
spruce about 10000 B.P. He thought that this 
spruce came from southeastern refugia after the 
Mackenzie valley became ice-free. Mackay and 
Terasmae (1963) described driftwood from a 
pingo among the Eskimo Lakes east of the 
Mackenzie delta dated at 10800 B.P. Miuiiller 


(1962, p. 262) found driftwood at a pingo near 
Tuktoyaktut dated about 12 000 years ago. 

Mackay & Mathews (1973) in a study of the 
geomorphic development of the Mackenzie River 
valley in the vicinity of Good Hope, described a 
section of deltaic and floodplain sediments that 
had been deposited in a lake probably held up by 
an ice dam in the main drainage line of the 
Mackenzie River below Good Hope. Water supply- 
ing this lake came “from the southwestern edge of 
the Mackenzie plain...via Mountain River,” 
which rises in the Mackenzie Mountains. Deposits 
in the bottom of this lake (wood), gave an age of 
11000 to 11500 years B.P. 

These data indicate that postglacial driftwood 
was coming down the Mackenzie River from 
somewhere above Good Hope, either from the 
Mackenzie itself or from the Mountain River. 
Prest’s estimate (1969) for the opening of the 
Mackenzie valley drainage about 10000-11000 
B.P. suggests that the wood may have been 
coming from both sources. If so it could have 
originated in the Liard River valley or from 
several other western tributaries of the Mackenzie. 
It is virtually certain that little or none of the early 
driftwood found in the delta or around Good 
Hope could have come from the southern parts of 
the Mackenzie drainage basin, to say nothing of 
deriving it from the assumed refugium in Alberta 
and Montana. Any that might have come out of 
the upper valleys of the Athabasca, Peace, Hay, or 
Buffalo Rivers would have been caught in the great 
lake that lay in the valleys of these rivers and in the 
basins of the present large lakes. 

We believe it reasonable to suggest therefore 
that populations of spruce probably lived through 
the last glaciation in the eastern valleys and 
foothills of the mountains west of the Mackenzie 
River. The forest may have been patchy in places 
or open forest-tundra, but probably there was no 
large discontinuity. 

All of the earlier proposals for the postglacial 
origins, migrations, and chronologies of these 
forests were made without regard to the diffe- 
rences among the white spruces. We can only 
suggest the effects of these differences, using what 
we know of the present ranges of the varieties of 
white spruce, and of their probable behavior since 
the disappearance of the last glacial ice. 

We presume that the populations on the eastern 
slopes of the mountains were of Alberta spruce 
(Picea glauca var. albertiana) with its array of 
ecotypes. inéarly. ‘or. quite intact’ Wihen’.the 


22 


Tuktoyaktuk Peninsula was free of ice with tundra 
established, this spruce would have been nearby 
and already adjusted for a forest-tundra habitat. It 
then began a long migration eastward and south- 
eastward, forming the arctic timberline and the 
subarctic open park-like forest. 

We have already noted the archaelogical fin- 
dings of Noble (1971, 1974) in the region northeast 
of Great Slave Lake, where an Indian culture was 
dated at about 7000 B.P. He also found charcoal 
in the soils that he could interpret as evidence of 
“natural” forest fires. His oldest date for burned 
forest (6900 years B.P.) came from the Snare River 
gallery forest area as did also his next oldest date 
(about 5089 years B.P.). This spruce probably 
migrated eastward from the Mackenzie valley by 
way of the Bear River and the shores of the Great 
Bear Lake, or via the northwest shores of ancestral 
Great Slave Lake. 

We have not seen the gallery forest that extends 
northeastward in the Thelon River valley, but 
judging by photographs of white spruce there, 
published by Clarke (1940), it also is var. 
albertiana and closely resembles that found at 
the eastern end of Great Slave Lake (Figure 8). 
The headwaters of the Thelon are not more than 
20 km from the site of the photograph in Figure 8. 
A photograph published by Blanchet in 1926a 
shows the same spruce growing among the Thelon 
headwaters. 

Gordon (1975) proposed that trees first came 
into the upper Thelon valley not long after 6000 
years B.P. and that forest advanced down the 
Thelon in a later expansion. He dated an arctic 
culture on the Thelon between 3200 and 2900 
years B.P., the excavations of which contained 
macrofossils of black and white spruce and tama- 
rack. Gallery forest along the Thelon presently 
constitutes its longest extension into the tundra in 
western Canada. It was mapped by Rowe (1972) as 
an isolated “island” rather than an extension and 
is about 200 km long. It may be a relict from a 
former extension, perhaps a remnant of the first 
great expansion of forest which successfully wea- 
thered subsequent colder periods. 

Terasmae & Craig (1958) discussed the ecolo- 
gical and climatological significance of fossils of 
Ceratophyllum demersum L., a species now limit- 
ed to a more southern range, and rather abundant 
pollen of spruce and pine, in a pingo in the Thelon 
valley (Craig, 1959). The authors (Terasmae & 
Craig, 1958, p. 568) say “the evidence seems to 
indicate that the silt was deposited during a 


postglacial climatic episode warmer than the 
present, the postglacial thermal maximum. [It was 
found to have a !4C date of 5400 + 230 years B.P.] 
The formation of the pingo is necessarily a later 
event and may coincide with the marked cooling 
of climate following the postglacial thermal maxi- 
mum.” If Gordon is correct in having trees along 
the upper Thelon soon after 6000 B.P., spruce 
should have been there to contribute its pollen. 
But the pine is a somewhat more southern species 
in the boreal forest (Raup, 1933a, 1946). Consi- 
dering the findings of Ritchie and Lichti- 
Federovich (1967, 1968) on the long-distance 
transport of pollens, pine pollen in the pingo silt 
does not prove that the pine was growing there at 
the time of deposit. 

We know from Noble’s dates for burned forest 
(1974) that the spruce was in the country northeast 
of Great Slave Lake about 7000 B.P. By air line 
this is about 1100 km from the Tuktoyaktuk 
Peninsula where it first appeared about 11500 
years ago. A very rough estimate of its migration 
rate is therefore about 0.24 km per year. Hopkins 
(1972, p. 141) stated that spruce first appeared in 
the Tanana valley of central Alaska about 8000 
years ago. If it came from the Mackenzie delta 
region it had migrated some 880 km in about 3500 
years. This is approximately the same rate, 0.25 
km per year, that it showed in its easterly exten- 
sion. The eastward migration must have followed 
the recession of the ice rather closely, for the latter 
is thought to have disappeared from Keewatin not 
later than 7000 years ago (Craig & Fyles, 1960; 
Prest, 1969). 

These long migrations are, in themselves, evi- 
dence that the Alberta spruce came through this 
last glaciation as a versatile, plastic taxon, relati- 
vely rich in biotypes, which suggests that its 
population in the northern mountains had not 
been greatly reduced. 

Following the general pattern of gallery forest 
advance, we assume that the first routes by which 
forests followed the ice retreat into the central part 
of the Mackenzie were down the valleys of the 
Athabasca, Peace, Liard, and other rivers flowing 
eastward from the mountains. The first white 
spruces in these valleys would have been var. 
albertiana with ecotypes which, from south to 
north, probably were progressively adjusted for 
life in boreal forest habitats. Evidence for this is 
found not only in the presence of the Alberta 
spruce in the existing flora of the Athabasca-Great 
Slave Lake region, but also of many other taxa of 


23 


woody and herbaceous plants whose geographic 
affinities are in the western mountains and foot- 
hills (Raup, 1946, pp. 63-78). 

The warming trend in the climate, together with 
abundant moisture in the valley bottoms, would 
have favored rapid migration downstream. The 
invasion of the central part of the Mackenzie basin 
was delayed during at least two still-stands in the 
drainage of the postglacial lakes down to the level 
of Lake McConnell. It is possible that migration 
occurred around the shores of the lakes, but, if so, 
the process would have been hazardous because of 
steady or episodic adjustments of water tables. 

A pollen profile of sediments from Lofty Lake 
in the upper Athabasca River region (Lichti- 
Federovich, 1970) shows a sequence somewhat 
different from that of Ritchie & Hare(1971). Lofty 
Lake is on the upland, 52 km from the Athabasca 
River. The base of the core, representing a Popu- 
lus—Salix—Shepherdia—Elaeagnus—Artemisia  fo- 
rest-shrub vegetation, was dated at 11400 years 
B.P. The poplar was replaced by spruce (6000- 
5700 B.P.) and other boreal forest trees which 
continue to the present. Populus balsamifera and 
P. tremuloides commonly occur along water courses 
(Jeffery, 1961) and their appearance here may 
represent the beginning of gallery forest along 
streams. The late appearance of spruce on the 
upland may reflect the probable tendency (discus- 
sed below) for the interfluves in this region to 
remain in some form of tundra or grassland long 
after the gallery forests had developed. 

We do not know when forest first came into the 
Cree Lake or Reindeer Lake regions, nor do we 
know whether the white spruce was of the eastern 
or western form. The eastern white spruce, Picea 
glauca var. glauca, having no subarctic ecotypes 
left in its populations, had to make new adjust- 
ments as its migration took place northward and 
northwestward. Possible routes for it into our 
region may have been up the Churchill River to 
Cree Lake or via the lakes and streams of the old 
fur trade route to the Clearwater River. At some 
time it accomplished this, for trees closely resem- 
bling it are now found along the lower Athabasca 
River where it grows with the balsam fir which is 
more southern in the boreal forest and not found 
north of the Athabasca delta. Whether it was ever 
able to produce a northward extension to 
Dubawnt Lake we do not know. If it did, it 
migrated much more slowly than did the Alberta 
spruce in its long migration eastward from the 
Mackenzie (see below). 


Recent work on the tree line has been done on 
archaeological problems in the Dubawnt, Thelon, 
and Kazan river systems. The tree line has long 
been recognized as a major cultural boundary 
between the people of the Arctic and the Indians of 
the boreal forest. Archaeological excavations ha- 
ve shown clear shifts in the cultural boundary 
during postglacial time, with southward advances 
and northward retreats of the arctic culture. For 
details of this research, the reader 1s referred to the 
following papers: Bryson, er al. (1965); Dennis 
(1970); Gordon (1975); Larsen (1965); Lee (1959); 
Nichols! (19674; 1967b,° 1967¢e)°-1969, 1970); 
Sorenson, et a/. (1971); Terasmae (1961, 1967); 
Terasmae & Craig (1958). Most of the material in 
these papers is summarized by Gordon (1975). 
Evidence of former extensions of forests into the 
tundra rests not only on fossil pollen (Nichols, 
1967a, 1967b) but also on forest soils now found as 
palaeosols in the tundra beyond the present limit 
of trees (Bryson, et a/., 1965); Larsen, 1965). 

The earliest of the palaeosols, and the farthest 
north in the Kazan drainage, was dated about 
6000 years B.P. This site was at the north end of 
Ennadai Lake. The earliest in the Dubawnt drain- 
age at Dubawnt Lake was at about 4000 years 
ago. It is stated by Gordon (1975, p. 35) that no 
charred podsols were found at Marjorie or Grant 
Lakes, indicating that these lakes, some 120 km 
northeast of Dubawnt Lake, had never been south 
of the timberline. 

Beginning somewhere in the country east of the 
east end of Great Slave Lake the black spruce 
gradually replaces the white spruce as the prin- 
cipal timberline species. Gordon (1975, p. 48) 
states that “Picea mariana, and to a lesser extent 
Picea glauca...comprise the dominant modern 
upper Thelon River vegetation. They extend from 
Eyeberry to Beverly Lakes, a river distance greater 
than 150 miles.” The last woods seen by J. B. 
Tyrrell (1898) on his journey down the Dubawnt 
River was a short distance south of Dubawnt Lake 
and was of black spruce. Baldwin (1951) noted 
black spruce as the primary species of this genus at 
or near timberline at Nueltin Lake. Rowe (1972) 
makes it the principal timberline species in north- 
ern Quebec. It may be that the eastern spruces, 
white or black, reached the timberline at Dubawnt 
Lake long after the Alberta spruce had got nearly 
to Beverly Lake, about 160 km farther into the 
tundra. This may be, in part, because they may 
have come from eastern refugia and had lost their 
subarctic ecotypes in the Pleistocene devastation. 


24 


The rate at which the interfluves were forested 
can only be surmized. The gallery forests probably 
were confined mainly to the valleys for a long time. 
The adjacent uplands seem to have become pro- 
gressively drier until the close of the xerothermic 
period 5000-6000 years ago. This would have 
favored the persistence of grassland or the drier 
forms of tundra. 

Natural grasslands are now of wide occurrence 
throughout the uplands west of the Canadian 
Shield. In modern times those in the upper Peace 
River region and southward have become farm- 
lands. Northward they extend to the upper 
Mackenzie valley. A reasonably good map of the 
distribution of these grasslands can be made from 
the range of the bison as it was known within 
historic times (see Raup, 1933b, and Soper, 1941 
for details of the former range of the bison). It was 
found throughout the uplands adjacent to the 
Athabasca, Peace, Hay, Buffalo, and Liard Rivers 
and it was along the Mackenzie River at least as 
far north as Fort Simpson, and northeastward 
adjacent to the base of the Horn Mountain 
plateau. 

Mackenzie (1801) reported a tradition among 
the Indians he met near the junction of the Peace 
and Smoky Rivers in the winter of 1792-93. They 
told him that the neighboring hills and plains, at 
that time grasslands interspersed with groves of 
poplars, were formerly covered with moss, and 
without any large game animals except caribou. 
Gradually the country changed to its present 
appearance, the caribou disappeared, and were 
replaced by elk and bison. Something like this 
must have happened in this area during the period 
between the disappearance of the ice and the 
closing centuries of the xerothermic period. Since 
then the bison and its range have dwindled to the 
smaller numbers of animals scattered through the 
prairie Openings found by Europeans when they 
came into the country in the 18th and early 19th 
Centuries. 

The aforestation of the interfluves of the 
Precambrian country may have been a somewhat 
slower process than it was west of the Canadian 
Shield boundary. There are no well-organized 
drainage systems on the crystalline rocks of the 
higher parts of the plateau. Rather, the major 
streams flow through mazes of lakes and are fed by 
innumerable small tributaries. Glacial drift in this 
rocky country is so scant that there is little 
continuity in riverine deposits that would support 
gallery forest. The presence of elaborately anas- 


tomosing waterways, on the other hand, may have 
favored slow advance on a broad front. 


The Advance of Forest South of Lake Athabasca 


In areas underlain by the Precambrian sand- 
stones, the glacial drift was relatively thick. Rivers 
and lakes were commonly bordered by sandy 
terraces or beaches along which gallery forests 
could have advanced more rapidly. Thus the Cree, 
MacFarlane, and William Rivers, flowing north- 
ward over the Athabasca Sandstone to Atha- 
basca and Black Lakes, may have developed 
gallery forests rather rapidly. 

The only '4C date we have for early forest in the 
Athabasca lake dunes is from charcoal found by 
Hermesh (1972, and pers. comm. 1977 & 1978) on 
what he thought to be a raised beach west of 
Yakow Lake. The charcoal was dated at 4920 + 60 
years B.P. (Rutherford er al., 1975). The charcoal 
was from beds of sand that could be distinguished 
from each other by slight differences in texture or 
compaction. These beds sloped 30° north. The 
charcoal included, “numerous chunks—some 
fairly large—1-3 cm. dia.” and appeared as lines 
across the surface of the ground. Apparently the 
wood was not identified. 

The form and position of the beds suggest that 
the charcoal was transported and deposited by 
water or wind. The exposure is near the delta of 
the MacFarlane River which may have brought 
the charcoal to the lake where it may have floated 
to nearby beaches. If so, it could have come from 
anywhere on the banks of that river, the head- 
waters of which are not far from Cree Lake. If 
carried by wind, it could have been deposited at 
intervals on the slipface of a dune, alternating with 
layers of sand. If our reconstruction and dating of 
the Lake McConnell shores in this area are even 
approximately correct the site of the charcoal 
(now at ca. 275 m above sea level) was at about 
213 m above sea level about 3500 years ago. The 
elevation and date are close to those we have 
estimated for the emergence of the Smith Rapids 
escarpment. The date suggests that the charcoal 
was redeposited because it is much older than the 
site in which it was found. 

The only other '4C date we have for the dune 
area is much younger 770 +80 years B.P. 
(Lowdon & Blake, 1980). It was based on charcoal 
of Pinus banksiana collected by one of our parties 
in 1975 in the Thomson Bay dune area (Lat. 59° 03’ 
Long. 109° 00’) near an elevation of 275 m. 


25 


The material was in large pieces, found lying on 
sand and covered by about 13 cm of sand over 
which was a single layer of small stones. The 
deposit probably represents a process that is now 
current in the dune area—burial of pine forests by 
blowing sand, in this case possibly by blowouts 
following the exposure of the sand by the fire that 
produced the charcoal. 

It is notable that, in spite of the many traverses 
that have now been made through the Athabasca 
dunes and over the gravel plains scattered among 
them, and in spite of the many pits that have been 
dug in them, the only ancient charcoal that has 
been found is that collected by Hermesh near the 
lower MacFarlane River. If the earliest trees to 
come into this region formed a gallery forest along 
the valleys of the larger streams and left the 
interfluves open, as we suggest, then the remains 
of forests would most likely be found along the 
streams and in their deltas. 

David (1981, pp. 306-308) has proposed that the 
Cree Lake dunes became stabilized by vegetation 
when the northerly winds replaced the southeas- 
terlies about 8800 years ago. He suggests that 
stabilizing vegetation came very soon after that 
date, but whether it included trees we do not 
know. The principal species now seen in the 
area, judging from his photographs, is jack pine 
except in wetlands where black spruce and/or 
tamarack are evident. Even with the change of 
winds this sandy country must have been very dry, 
for the xerothermic period was building up toward 
the maximum which came 2000-3000 years later. 
It seems more likely that neither pines nor white 
spruce came to the interfluves until the close of the 
xerothermic period. The pines are obviously still 
unable to grow on the barren tops of the ridges. 


Suggested Times of Aeolian Sand 
Activity 


From our hypothesis that the advance of forests 
into most of the region was by gallery extensions 
in stream valleys, it follows that the adjacent 
uplands were open for the movement of sand 
deposits by wind long after trees had reached the 
central part of the region. The vegetational con- 
trasts formed in this way probably were greatly 
accentuated by the warmth and dryness of the 
xerothermic period. 

The exposure of land surfaces between the 
Canadian Shield boundary and the Rocky Moun- 


tains was progressive from west to east due to the 
drainage of postglacial lakes Peace, Tyrrell, and 
McConnell, interrupted by still-stands of un- 
known length. We have derived a tentative date 
for the formation of Lake McConnell at about 
8560 years B.P. (Table 1). 

Judging by present-day elevations and esti- 
mated times, the lowering of Lake Peace may have 
been at an average rate of about 12.2 m per 
century, and Lake Tyrrell at about 17.4 m per 
century. Though these rates are speculative, the 
estimated rate for Lake McConnell is conspi- 
cuously slower: about 1.46 m per century in the 
north arm of Great Slave Lake. Using the same 
assumed elevations and times, land exposed by the 
drainage of Lake Peace would now be between 
13 500 and 10000 years old; by that of Lake Tyrrell 
between 10 000 and 8500 years old; by that of 
Lake McConnell to the separation of Athabasca 
and Great Slave Lakes between 8500 and 3300 
years old; and by that of the present Mackenzie 
lowland below the Fort Smith escarpment bet- 
ween 3300 years old and the present. 

The upland glacial drift west of the Canadian 
Shield boundary, which consists of fine-textured 
materials, has not been as susceptible to aeolian 
influence as that east of the boundary. With its 
much greater water-holding capacity, it was soon 
able to support denser vegetation. Nonetheless, it 
probably was restricted for a long time to some 
type of tundra or tundra grassland, much of which 
still persists as prairie openings in the boreal forest 
of the region. 

Wherever there were deltaic or lake beach 
deposits reworking by wind was active. Most 
higher level deposits probably came into existence 
during the drainage of Lakes Peace and Tyrrell, 
between 13 000-14 000 years and about 8560 
years ago; larger ones at lower elevations probably 
appeared in the last +8560 years during the 
formation and drainage of Lake McConnell. The 
complete distribution of deltas in the region is 
unknown, those that have been mapped total 
upward of 22533 km?. 

The southernmost Precambrian sandstone 
area, in the Cree, Athabasca, Black Lakes region, 
seems to have been free of ice as early as about 
9000 years ago. By this time Lake Tyrrell appa- 
rently had been drained nearly to the uppermost 
level of Lake McConnell. If our calculations are 
tenable, the area south of the proposed south 
shore of the Lake Athabasca extension of Lake 
McConnell became exposed through a progres- 


26 


sive increase of about 251 m of elevation in about 
1440 years. The area between this shore and the 
south shore of the present Lake Athabasca was 
exposed much more slowly during the past 8560 
years, but probably at a more steady rate than in 
the preceding 1440 years. 

It is probable that the sandy glacial drift south 
of the present Lake Athabasca was exposed to 
intense aeolian activity at least until the close of 
the xerothermic period. The fact that the active 
dunes are still present suggests that the trees have 
never been able to stabilize the sand near the shore 
under the climates that have prevailed since the 
xerothermic period. It appears that active dune 
habitats have been continuous in this area for at 
least 9000 years. 

The sandy country east of Great Slave Lake and 
northward to the arctic coast has had a different 
history because most of it is in the arctic tundra 
beyond the limit to which forests have penetrated. 
It is a broad plain extending northward from the 
middle Thelon valley to the middle Back River, 
eastward to uplands north of Baker Lake, north- 
westward to the Coppermine River, the arctic 
coast, and around the northeast part of Great Bear 
Lake. The surface is clothed with very sandy drift 
like that south of Lake Athabasca and there are 
thousands of square kilometers of eskers and 
drumlins composed mainly of sand (Wilson, 1939; 
Taylor, 1956). Most of the region probably has 
been free of ice, according to Craig & Fyles (1960), 
for at least 7000 years, the western parts for 
perhaps 9000 years (Prest, 1969). 

Geologists, archaeologists, surveyors, and ca- 
sual travelers who have seen this country have 
mentioned blowing sand, usually forming blow- 
outs or dunes. The tundra has been described as 
very dry and having scant vegetation in areas not 
supplied with water by small streams or near the 
shores of shallow lakes and ponds. A recent visitor 
to this region, Dr. J. S. Rowe (pers. comm.), 
reports that there are indeed large active dunes 
within the Thelon basin, derived from major esker 
trains. 

Our observations in the Athabasca dunes have 
shown clearly that, in the presence of very strong 
winds, neither herbaceous nor low woody plants 
can completely stabilize loose sand, even under the 
growing conditions of the boreal forest. We 
suggest that for at least 2000-4000 years the 
xerothermic climate made a sand desert of the 
arctic plains, with aeolian activity much greater 
than it is now. The available descriptions of the 


tundra suggest that it would not take a much drier 
climate to reactivate it. We do not know how 
much longer the warm-—dry period may have been 
effective in that region. Two periods of warmer 
and presumably drier climate (2700 to 2200 years 
B.P. and 2000 to 800 years B.P.), both less severe 
than the xerothermic period, were proposed by 
archaeologists in their studies of cultural changes 
in the vicinity of the treeline (Sorenson ef al., 
1971). 

Physiographic studies in the major sand areas of 
the Precambrian region are incomplete and thus 
the total effect of wind is unknown. Large tundra- 
stabilized dunes have been seen ina few places, but 
in forested areas they may not appear on aerial 
photographs. A major effect of wind on the plains 
north and northwest of the Thelon River may have 
been on the shape and continuity of the sandy 
eskers. The elongated ridges south of Lake Atha- 
basca have been greatly altered by wind, and in 
places converted to isolated hills with rounded 
forms. 


Shore Processes in the Lake Athabasca 
Sand Dune Region 


The history and development of the Lake 
Athabasca dunes seem inseparable from the shore 
processes that have been effective during the past 
10 000 years as the shorelines of Lakes Tyrrell and 
McConnell receded northward across a gently 
sloping plain of sandy glacial drift. 


Wind Directions 


The most effective wave-producing and sand- 
moving winds in the Athabasca dune region now 
come off the lake from the northeast or from the 
westerly quadrants. The directions of prevailing 
and storm winds in the Mackenzie basin during 
the last 10 000-14 000 years are speculative but it is 
clear that there have been major changes. David 
(1981, see above) applies to all of the Mackenzie 
basin his explanation that there was a change from 
dune-forming southeasterly winds in the Cree 
Lake region to the later ones from the northwest 
which came after about 8800 B.P. If this and our 
own estimates for lake chronology are approxi- 
mately correct, the shore processes described 
below would have become effective about the time 
Lake McConnell was formed. When this hap- 
pened, onthe southern shores of Lake McConnell, 


2h 


the west, northwest, and northeast winds would 
have blown unimpeded a much greater distance 
across open water than they do on the present 
shores. From the northeast the distance was only 
about a third larger, but for westerly winds it was 
seven to eight times as great. For perhaps 4000- 
5000 years the winds when over the land, whether 
from the southeast, northeast, or west, were 
mostly unobstructed by forests. 


Wave Action 


The period in which wave action is possible is 
strictly limited to the ice-free period, which on 
Lake Athabasca usually lasts from about mid- 
May to sometime in October. The most effective 
winds during this season come with violent 
storms. Winds from the northeast are usually 
accompanied by a certain amount of rain. These 
storms appear to be cyclonic and are followed by 
usually dry northwest and west winds of nearly 
equal force. Occasional winds of gale force also 
come from the southwest and, though they may 
continue unabated for three or four days, they are 
infrequent. Although these winds may not have 
direct effects upon the south shore, they may 
temporarily alter the water level in the eastern part 
of the lake and, thus, affect the strand lines. 

Points of land jutting into the lake affect the 
disposition of sand and other sediments. Some 
sand apparently goes into off-shore bars, which 
are Clearly visible in certain aerial photographs 
(Figure 9). Smith (1978) counted 23 bars in the 
shoals near William Point. Some of the sand is 
carried along the shore to form shoals off points of 
land and in bays with lee shores behind the points. 
These effects are seen at William, Beaver, and 
Wolverine Points on the south shore and also at 
the mouth of MacFarlane River. The nearly sym- 
metrical distribution of shoals off the points 
suggests that winds from the northeast and north- 
west are equally effective in moving the shore 
sands. 


Ice Push 


On the shores of the large northern lakes ice 
push is due to the movement of windblown masses 
of ice over the surface of the lakes (Tyrrell, 1909; 
see also Scott, 1926, for a general discussion of ice 
push). As the ice melts in the spring it disappears 
first from the shores, leaving lanes of open water 
surrounding central bodies of floating ice. The 


Figure 9. Vertical aerial photograph of the offshore bars deposited around a small point of land between 
Wolverine Point and the MacFarlane River. (Sask. Dept. Tourism and Renewable Res. 
photograph YC 7624-64.) 


Figure 10. Ice push ridge at Poplar Point composed of sandstone slabs. The trees on the ridge are Pinus 
banksiana, Betula neolalaskana, B. occidentalis, and B. X winteri. 


28 


remaining ice mass can be moved by ordinary and 
storm winds. When an ice mass hits a shore it 
drives shore materials into ridges or greatly modi- 
fies any ridges already there. Great boulders are 
often forced inland for many meters and some- 
times plow a trench as they are shoved along. The 
ridges of heavy sandstone slabs near Poplar Point 
(Figure 10) probably were pushed up by ice. 


Beaches 


Existing sand beaches are unstable due to wind, 
wave, and ice action and to fluctuation in lake 
levels over periods of time that are within the life 
spans of any plants that might stabilize the sand 
(see Stockton & Fritts, 1973; Raup, 1975). The 
sand is worked into small dunes and ridges, often 
subtended by small lagoons, and temporarily 
stabilized here and there by scattered herbaceous 
perennials and a few shrubs (Figure 11). Some 
of these plants also are common on the large 
inland dunes. 


Shore Ridges 


Immediately back of the present beaches is a 
series of raised “fossil beaches,” all but the lowest 
of which have long been protected from wave and 
ice action. Ina few places, suchas at Turnor Point, 
they are of gravel, but most are of sand. They 
range in height to 35 m or more above the lake and 
are separated by long narrow lagoons or by dry 
intervales. They have become partly stabilized by 
dune grasses, shrubs, and/or by Picea glauca var. 
albertiana (Figures 7 & 11). The stabilization is not 
complete, for the sand is dry and easily blown out 
by the wind. The tops of the ridges acquire a 
“srooved” appearance, and the direction of the 
grooves depends upon the angle between the trend 
of the ridge and the direction of the wind. 
Northwest winds on this shore produce diagonally- 
orientated blowouts on most of the ridges. Elon- 
gated ridges farther from shore also show the same 
process. These blowouts can be seen in all stages of 
development. Many ridges are thus reduced to 


Figure 11. Beach and sand ridge at Thomson Bay. The pond near the lake edge is filled with Carex 
aquatilis ; on a beach dune behind it is a thicket of Salix planifolia ssp. planifolia and ssp. 
tyrrellii and Myrica gale; the the sand ridge is partly stabilized by Picea glauca var. albertiana 


forest. 


series of dune-like hills, with dune slipfaces on the 
lee fronts. Sand blown out of the ridges immedia- 
tely falls into the intervales between them and, 
depending upon the thickness of the ridge sand 
and the space available, parabolic dunes are 
formed. In general, the ridges are more or less 
parallel to the present shore but exceptions occur 
on projections of land, such as William Point, or 
among ancient beach ridge systems far back from 
the present shores. 

The origin and development of the high shore 
ridges require further study. Hermesh (1972) 
treated them as dunes, perhaps as “foredunes” in 
the sense of Cooper (1958) and others. It is more 
likely that they originated as offshore bars modi- 
fied by wave action and ice push as isostatic 
rebound brought them above lake level where they 
could be partly stabilized by vegetation and 
modified by wind. Smith (1978) dug pits on a high 


shore ridge near Ennuyeuse Creek and found 
many coarse inclusions in its sand. He suggested 
that lake ice either brought them from other 
shores or dredged up offshore stones and deposit- 
ed them in an ice push ridge. 


River Deltas 


The largest streams flowing into the lake bet- 
ween the Athabasca and Stone Rivers are the 
William and the MacFarlane. The William River 
has built a delta that extends about 13 km intothe 
lake and is about 13 km wide at the base (Figure 12). 
The position of this delta on the shore of the lake is 
conducive to maximum movement of the sand by 
waves and wind, for it is on the northward bulge of 
the south shore where there are wide stretches of 
open lake to the northwest and the northeast. The 
MacFarlane River delta, on the other hand, is near 


wcll e: ORE 


*cencstlatpptiaiee 


Figure 12. Oblique aerial view of the William River delta showing a series of old, partly stabilized beach 
ridges. The Thomson Bay dune field appears in the upper right. (National Air Photo Library 


photograph A 2595-5.) 


30 


the beginning of a northward trend of the lake 
shore, so that northeasterly storm winds are not as 
effective as at William Point. The MacFarlane 
may deliver less sand to the lake than does William 
River, though we have no data to support this. 


Plant Habitats in Regions of 
Actively Blowing Sand 


Our primary interest in the Lake Athabasca 
sand dune area is botanical—its flora and vegeta- 
tion — and our object here is to describe the plant 
habitats and the vegetation of the region. The 
habitats available for plant life vary from dry 
sand, continuously blown about by the wind, to 
relatively stable soils and surfaces with moisture 
regimes from dry to wet. 

Two hundred and sixty-six kinds of vascular 
plants have been found in the area, about 80 
percent of which are characteristic of and more or 
less wide-ranging in the boreal coniferous forest 
region. The remaining 20 percent come from 
northern grasslands, arctic tundra, or the northern 
cordillera. About 40 of them are so constituted by 
low moisture requirements, growth habits, and 
tolerance of abrasion and burial by aeolian sand, 
that they can live on the open dunes. At the other 
extreme is a much larger number tht are restric- 
ted to wetlands such as muskegs and lake shores. 
Between the extremes are many plants that have 
varying tolerances on both the moisture and 
physical disturbance gradients. Local differences 
in the temperature: patterns probably have little 
effect upon plant distribution in the region. 

Some major factors influencing the habitats of 
the region are: (1) relatively low precipitation, a 
short growing season, and frequent high winds; (2) 
sandy soils derived from glacial tills that have been 
progressively reworked by shore processes and 
wind on the receding strandlines of postglacial 
lakes; (3) fire that, by maintaining a degree of 
instability in the forest vegetation, has favored 
fire-adapted species; and (4) wetlands that have 
been produced by a relatively high water table and 
the alteration of drainage systems by the deposi- 
tion and deflation of aeolian sand. 

The active sand dunes present a varied and 
biologically demanding set of environmental con- 
ditions for plant growth. For these reasons it is 
important for us to define the different kinds of 
aeolian depositional and erosional features in the 


31 


area so that these features can be discussed in 
relation to the vegetation. 


Dunes and Dune-forming Processes 


Sand dunes result from the interaction of sand, 
wind, and water. Wave action sorts shore ma- 
terials and delivers sand to beaches where it can be 
blown by wind. On the south shores of Lakes 
Tyrrell, McConnell, and Athabasca sand has been 
abundant, and the rising land surface has brought 
the beach sands up into the winds more rapidly 
than otherwise would have been the case. Ice push 
has furthered this process. Diversity and irregula- 
rity in the resulting land forms are due to their 
positions with respect to prevailing winds, to 
vegetation, and to frequent fires that have affected 
the control of the sand by the vegetation. 

An examination of the sand dune areas on aerial 
photographs (and by flying over them) reveals a 
bewildering array of forms, ground plans, and 
orientations. Our attempts to fit them into the few 
standard categories described in the literature 
have not been completely satisfactory. Smith 
(1978) was probably correct in thinking that much 
of the difficulty in dune classification is due to the 
wide range of variation in effective winds (see 
below). It is probable that the dune forms and 
orientations in the area will not be rationalized 
until adequate data on the direction, intensities, 
and seasonality of these winds have been accumu- 
lated. Their general effectiveness rests upon the 
nearness of the dune areas to the open lake and 
upon the prevailingly dry climate of the region. 

We have no data on precipitation in the dune 
areas but extrapolation from Uranium City and 
Chipewyan records suggests that the total for the 
year averages 36-40 cm. About 25 of this comes as 
rain, roughly half of it in the growing season 
(June, July, and August). Rain seems to have only 
a temporary effect on the movement of dune sand. 
In making moisture profile measurements two 
days after about three days of heavy rain Hermesh 
(1972) wrote, “The surface 5 cm were dry and 
blowing.” The winter snow is relatively dry and 
powdery and gets mixed with blowing sand. A 
trapper near Ennuyeuse Creek told us that winter 
travel on the dunes with sleds was impossible 
because the sleds would not run on this mixture. 
As yet we have no way of evaluating the movement 
of sand by the winter winds. 

In view of the above-mentioned deficiencies in 
our knowlege of factors governing the geography 


of the dune areas, and in view of our major 
purpose, which is the delineation of the history 
and present condition of plant habitats in the 
dunes, we are constrained from attempting a 
thorough classification of the dune forms. These 
forms are of less significance for our purpose than 
the general prevalence of windblown sand. In 
order to facilitate the discussion of vegetation, 
however, we will describe some of the most 
conspicuous aeolian depositional and residual 
forms. In doing this, we will attempt to avoid 
genetic classifications that imply more than we 
know about the origin of the features and we will 
treat the multitude of forms mainly on a descripti- 
ve level. The outline of our presentation is as 
follows: aeolian depositional features: parabolic 
dunes, oblique ridge dunes, transverse dunes, 
precipitation ridges, and other dune features (sand 
hillocks, sand sheets, and rolling dune topogra- 
phy); aeolian residual features: gravel pavements 
and dune slacks. 


The Sand Supply 


The sand supply for the Lake Athabasca sand 
dunes is ultimately provided by the Athabasca 
Sandstone that underlies the region and from 
which sandy glaciofluvial materials were derived. 
As the lake levels of Lakes Tyrrell, McConnell, 
and Athabasca dropped through drainage and as 
the land level rose by isostatic readjustment, the 
glaciofluvial materials were worked by water and 
ice action and lacustrine deposits were exposed to 
the wind along the south shores of these lakes. At 
the same time, the major streams from the interior, 
the William and MacFarlane Rivers, which today 
mark the major dune fields, carried large quantities 
of sand into the lakes. 

The large dune fields are actively enlarging on 
their eastern and southern perimeters, more ra- 
pidly on the former than the latter, and in some 
places even on their western edges (Figures 54 & 
56). In only a few places do the dunes come out to 
the lake edge (Figure 58). In most places a series of 
plant covered and semistabilized ridges and hol- 
lows separates the dune fields from the lake and a 
supply of new sand. It is probable that the amount 
of new sand being delivered to the active dune 
fields has diminished (David, pers. comm.) and 
some evidence of sand starvation has been observ- 
ed. Isostatic readjustment is still continuing, as 
shown by series of uniformly spaced offshore bars 
(Figure 9) that occur in many places along the 


32 


shore. However, the rate of rise is probably less 
than it was in the past. Noble (pers. comm.) using 
14C dates on successively lower beaches around the 
eastern part of Great Slave Lake, concluded that 
isostatic adjustment was still active, though pro- 
gressively slower during the last 2000 years. 

If our concept of the northward advance of trees 
is acceptable, a gallery forest of Alberta white 
spruce probably had reached the shores of Lake 
McConnell via the William River at least as early 
as 8500 years ago. Pines may not have reached the 
shore area until the close of the xerothermic 
period, perhaps 5000 or 4000 years ago. The 
present pattern of shore ridges, dune fields, and 
forests probably has been duplicated repeatedly 
during this time, not in exact detail but in 
general outline, and the function of the white 
spruce as a partial stabilizer of the sand probably 
has been effective for 4000-5000 years longer. 
Under these circumstances, and assuming that the 
isostatic rebound still continues, the stabilization 
process that we see going on now may well be 
transient. 

The apparent stabilization of sand along the 
shore and among the dune fields becomes still less 
impressive when the effects of fire are considered. 
All of the forests that border the large fields are 
extremely susceptible to fire and have been burned 
repeatedly. The fires have been started by light- 
ning or from the campfires of the Indians who 
probably have inhabited the region as long or 
longer than it was forested. 

Forest fires within 15-25 km of the lake shore 
expose the sand to the winds and initiate blow- 
outs, of which there are a great many current 
examples. Most of them start as small parabolic 
dunes and those farthest from the lake may 
continue and enlarge as such to the proportions of 
the ones seen near Archibald Lake and in the 
Maybelle River area. There is some evidence that 
the smaller dune fields such as those on both sides 
of Wolverine Point started from fire-induced 
blowouts. 


Aeolian Depositional Features 


Parabolic Dunes 

The most common dunes in the forested region 
south of Lake Athabasca and on the forested 
borders of the large dune fields are parabolic in 
plan view with tails pointing to the windward and 
a convex face on the downwind side. Parabolic 
dunes appear as both active and inactive (paleo- 


dunes) features. They were equally common in the 
past, to judge from the large number of stabilized 
border ridges and associated patterns that traverse 
the landscape. 

Cooper (1958) described parabolic dunes form- 
ed by the rejuvenation of partly or wholly plant 
covered sand dunes. Changes in climate, wind 
direction, or more commonly fire, may initiate 
breaks in the vegetation cover leading to the 
formation of blowouts and the reactivation of the 
sand. Blowouts may take the form of saucers or 
troughs (Figure 13). Saucer blowouts are small 
and often short lived unless they merge with other 
such forms; then the possibility of their developing 
into parabolic dunes is greater. Trough blowouts 
are large and trough-shaped and characteristically 
lead to parabolic dunes. According to Cooper 
(1958, p. 74) “Three conditions are necessary for 
initiation of a trough blowout and its development 
into a parabolic dune: (1) considerable thickness 
of sand, (2) a surface stabilized by vegetation, but 


with points of weakness, and (3) essentially unidi- 
rectional effective wind.” 

Parabolic dunes may exist in a number of forms 
(David, 1977). They may be symmetrical, asym- 
metrical, filled, or partly filled. Their tails, which 
are produced by the lateral scattering of sand as 
the dune advances, may be traced for long distan- 
ces. These parallel ridges were described by Hack 
(1941) as “longitudinal dunes.” The concept of the 
longitudinal dune as one originating from a 
parabolic dune that has broken through its advan- 
cing head has also been proposed by Verstappen 
(1968) and by Cooke & Warren (1973). The “Cree 
Lake type” recently discussed by David (1981) are 
considered by him to develop as parabolic dunes. 
Such longitudinal dunes would have been formed 
by a unidirectional wind and would not fit Coo- 
per’s multidirectional wind hypothesis (1958) or 
other views on the origin of longitudinal dunes as 
summarized by Mabbutt (1977). Because of the 
confusion that would be introduced by using the 


Figure 13. Trough blowout cutting through a jack pine forest northeast of Little Gull Lake. The trough is 
narrow and about 9 m deep. Its gentle, peripheral slopes are being stabilized by Hudsonia 
tomentosa along with Calamagrostis, Festuca, Deschampsia, and Tanacetum. 


33 


term longitudinal dune or longitudinal ridge for 
the tails of a parabolic dune we will here use the 
term border ridge (David, 1977). 

North and east of Archibald Lake the upwind 
“tracks” of the active parabolic dunes show evi- 
dence of many lesser blowouts and parabolic dunes 
that are still active enough to appear on the aerial 
photographs. Seen from the air, they make a 
curious lace-like pattern which appears to be the 
“embroidery” pattern described by David (1977). 
This pattern covers many square kilometers in the 
Archibald Lake area (Figure 57) though active 
parabolic dune fronts may be absent. Something 
like it also is Shown in Figure 14 where it occupies 
long “corridors” between the prominent east-west 
ridges that have been interpreted as elongated 
drumlinoid features (the “ispatinows” of Tyrrell & 
Dowling, 1897). 


The variation in size and area of parabolic 
dunes is great. North of Archibald Lake four small 
parabolic dunes are coalescing and moving into 
the lake (Figure 57). The largest of these dunes 
is 1.2 km long and 0.4 km wide. The original 
parabolic dunes that made up this complex are 
still distinct and their border ridges can be traced 
to the northwest. The dune complex west of the 
Maybelle River is also the product of the coales- 
cence of two or more large parabolic dunes. This 
dune complex covers about 25 km? and has 
formed a dune field that supports a large series of 
transverse dunes (Figure 53). Border ridges which 
trace the movement of these dunes from the 
northwest are still visible. The Wolverine Point 
dune fields appear to be still larger parabolic dune 
complexes which have formed by the confluence 
of several individual dunes. The dune tracks and 


Figure 14. Oblique aerial view of the Lake Athabasca shore between Wolverine Point and the MacFarlane 
River. The foreground pattern of stabilized border ridges and precipitation ridges is the 
embroidery” pattern referred to by David (1977). The MacFarlane River dune field appears in 
the upper right. (National Air Photo Library photograph A 2595-66.) 


the inland border ridges are visible on aerial 
photographs. 

David (1977) would derive all of the dune fields 
south of Lake Athabasca from parabolic dunes 
and there is some evidence to support this view. 
The northern edge of the MacFarlane River dune 
field. (Figure 59) shows a series of parabolic 
dunes separated by narrow bands of forest for- 
ming a series of “in succession parabola dunes” 
(David, 1977). In the main dune field south of the 
“in succession” dunes, however, evidence of the 
possible origin of the dune field from parabolic 
dunes is obscure. The origin of the William River 
dune fields is even less clear and it could be 
concluded from the evidence that this and other 
large fields have always existed as we see them 
today. 

Two methods were used to determine the rate of 
movement of a parabolic dune complex at the 
eastern margin of the Wolverine Point dunes. The 
first method was applied to a small pine less than 


40 years old that was partly buried by an ad- 
vancing dune front and whose completely covered 
lower branches were dead (Figure 15). The age 
of the tree at the uppermost of the dead branches 
was subtracted from total age. The distance from 
the base of the tree to the edge of the dune front 
was measured and an advance of about 50 cm in 
the preceding five years was obtained. A second 
method was used where the slope of the dune front 
and the height of the front were much less. The 
growth rings in small trees growing in the open are 
nearly circular and concentric. When sand begins 
to cover a tree and to press upon its stem, 
compression wood develops on the side opposite 
that on which the pressure is applied. Thus the 
growth rings become oval and eccentric. By 
counting the number of years since this eccentric 
growth began ina tree about 40 years old emerging 
from a dune front about 1.5 m from the edge of the 
front, it was estimated that a 1.5 m advance had 
occurred in the preceding five to ten years. The 


Figure 15. Precipitation ridge at the margin of the Wolverine Point dune field invading a Pinus banksiana 
forest. 


first method of calculation gave a rate of advance 
of 10 cm per year, and the second method gave a 
rate of 15-30 cm per year. 


Oblique Ridge Dunes 

In the large dune fields at the William River 
there occur the most massive and conspicuous 
dunes in the Lake Athabasca region (Figures 
16 & 17). These dunes have a shallow parabolic 
shape in plan view, convex to the northeast 
(Figure 19). About 40 of them form a band 
through the center third of the field west of the 
William River and several occur east of the river, 
the former trending in a northwest - southeast 
direction (Figure 54). Hermesh (1972) gave the 
orientation of these dunes as N32 — 41° W in the 
northern part and N53 — 61°W in the southern 
part. The larger dunes vary in length from 0.5 km 
or less to about 1.5 km. They are free-standing on 
a broad plain-like surface that slopes gently to the 
north. This surface is flat to gently rolling and 
most of it is covered with a gravel pavement on 
which there are occasional sand lenses or hillocks. 


Some of these dunes rise more than 35 m above 
their base but others, particularly in the south- 
eastern part of the area, are low and indistinct. 
Their crests are sometimes rounded (Figure 18) 
but most have slip faces on the southeast side or on 
both sides with a “knife-edge” crest between 
(Figure 17). 

In profile one of the higher dunes with a “knife- 
edge” crest had steep eastern and western slopes, 
the former being slightly steeper. Below the crest 
the steep easterly slipface bellies out and is roun- 
ded convex to the base. The western slope presents 
a smooth unbroken profile becoming progres- 
sively less steep toward its base. A windrow of 
organic debris, probably moved by a recent strong 
westerly wind, was located about two-thirds of the 
way up the western slope of the dune. 

Some oblique ridge dunes have prominent 
peaks and cols, sometimes as many as three 
(Figure 38). On the western side of the dunes 
there may be a ridge located behind each peak 
(Figure 18). These ridges may be formed by the 
channeling of wind around the peaks of the dunes, 


Figure 16. Aerial view of an oblique ridge dune moving across a gravel pavement plain in the William 
River dune field. This northwesterly view shows the lee slope of the dune which is partly 
covered by herbaceous flora (cf. Figure 38); Lake Athabasca appears in the distance. 


Oblique ridge dunes characteristically have a knife-edge crest. A series of other oblique ridge 
dunes and Lake Athabasca appear in the distance. (Photograph by R. Hermesh.) 


18. The gently curved windward slope of an oblique ridge dune looking toward the south 
southwest. Sand ridges sometimes join the main the dune at right angles. 


a7 


the lateral erosion of the windward sides of the 
dunes, and deposition behind the peaks. Tapering 
tongues of sand appear at the ends of the dunes. 
These usually point southwestward, but some are 
directed northeastward as well. New sand avail- 
able to these dunes seems to be limited to what can 
be winnowed from the sandy-gravel till overlain 
by gravel pavement on which the dunes sit and 
from the surrounding sand hillocks and sheets. 

Oblique ridge dunes in the William River area 
are strongly influenced by winds from more than 
one direction. Local meteorological data are not 
available for the area but our field parties have 
experienced very strong winds from the northeast, 
northwest, west, and southwest and we have seen 
some small dunes orientated to southeasterly 
winds. At the western end of Lake Athabasca, gale 
winds from the southwest were experienced in 
August, 1930. Late in July of 1935, there was a 
four-day gale from the northwest followed by two 
days of very strong northeasterly winds; in August 
there was a series of gales or very strong winds 
from the southwest (2), northwest (6), and north- 
east (2). On 16 August 1935, a strong north- 
westerly wind was blowing “clouds” of sand, 
clearly visible at a distance, off the western 
slipfaces of the large oblique dunes and distri- 
buting it on the eastern slopes of the knife-edged 
ridges. There is also botanical evidence to suggest 
that westerly winds are predominant during the 
growing season. On oblique ridge dunes herba- 
ceous vegetation occurs only on the east side of the 
base of the dunes. In order for seedlings to become 
established they must be located where sand is 
accumulating slowly and where the surface is not 
eroding (see below). This condition would prevail 
on the east side of the dunes only if westerly winds 
were predominant. 

The action of contrary winds on oblique ridge 
dunes may have slowed their easterly movement, if 
it has not actually stopped it. A comparison of 
aerial photographs taken in 1957 and in 1976 
(Figure 19) shows no appreciable change in form 
Or position in the oblique ridge dunes. Using 
our figures for the rate of advance of precipitation 
ridges and transverse dunes their movement could 
not have been more than 12 m during the 19 years 
between photographs, and would not be discern- 
able on the photographs. But the photographs do 
show that vegetation has expanded during that 
time both at the northern edge of the dune field 
and in the lee of dunes. This may indicate a 
slowing in the rate of sand movement. 


38 


The name for the high dunes, which we call 
oblique ridge dunes, has been a persistent source 
of confusion. Hermesh (1972, p. 122) termed them 
“longitudinal dunes” and commented that “suc- 
cessive dunes are often aligned along the same axis 
forming dune chains.” The aerial photographs 
(e.g., Figure 54) suggest that some of them are 
rather roughly aligned from northwest to south- 
east; but the longest continuous group is only 
about 1.6 km long, no longer than the largest 
single dune. Those that seem to be in rough 
alignment are commonly more than 0.8 km out of 
line. It is doubtful that the “chains” are any more 
than a suggestion of continuity. Rowe & Hermesh 
(1974) called them “seif dunes” but David (1977) 
stated that this term should not be used because 
seifs are straight continuous ridges that extend 
over long distances. Smith (1978) called them 
“transverse dunes” apparently following David 
(1977), who suggested at that time that they may 
be the same as this more unstable, shorter-term 
dune form which may be affected readily by winds 
of varying directions. If they are formed by winds 
from two directions only, they would be orien- 
tated to the resultant of these winds. Cooper 
(1958) termed such dunes “oblique ridge dunes” 
and we feel that his concept best fits the high dunes 
in the Lake Athabasca area. David (pers. comm.) 
claims that the name “open parabola dune” should 
be applied to them because of their shallowly 
parabolic shape in plan-view and because of a lack 
of information on the wind directions that control 
these dunes. We have decided that there is suf- 
ficient evidence that these dunes are influenced by 
winds of more than one direction, at least during 
the summer, to justify using Cooper’s name - 
oblique ridge dunes. 


Transverse Dunes 

Transverse dunes are orientated at right angles 
to the direction of the effective wind and concave 
to windward. The lee slopes are slipfaces that are 
as steep as the sand will hold, usually averaging 
33°. The slipface may extend to the top of the ridge 
but more often the upper edge breaks from a 
gently rounded upper surface which is confluent 
with the upper windward slope at the top of the 
ridge (Figure 20). In some places, even in the 
absence of vegetation, the slipface may be absent 
and the lee slope is gentle from top to bottom 
(Cooper, 1958). 

Authentic free-standing transverse dunes in the 
central parts of the large dune fields appear to be 


ee ee eT 


1 km 


Figure 19. Vertical aerial photographs comparing oblique ridge dunes and patches of vegetation at the 
northern edge of the William River dune field. Photograph A was taken in 1957 and enlarged to 
the same scale as B taken in 1976. There is no evident change in the shape or position of the 
oblique ridge dunes during the 19 year period. A conspicuous change is visible, however, in the 
development of vegetation during that time within the dune field and at its borders. (A. 
National Air Photo Library photograph A 15611-9; B. Sask. Dept. Tourism and Renewable 


Res. photograph YC 7624-18.) 


rare because most of the effective winds in these 
fields are not unidirectional. Those we have seen 
are in localities where the northeasterly winds are 
relatively ineffective due to obstructions formed 
by forests or points of land. Most of those mapped 
by Hermesh (1972) are in the northwest part of the 
Thomson Bay field where they are more or less 
protected from northeasterly winds by Beaver 
Point, and in the northern part of the William 


39 


River field where William Point has the same 
effect. Hermesh gives the orientation of those he 
identified as 312°-025°, indicating that they were 
being moved by westerly winds varying from west 
northwest to southwest. Transverse dunes also 
occur as large fields in the parabolic dune com- 
plexes such as the Maybelle River dunes 
(Figure 53) and the Wolverine Point dune field 
(Figure 58). 


Figure 21. Blowing sand drifting across a “willow dune” in the Thomson Bay dune field. Salix silicicola 
appears in the foreground and S. planifolia ssp. tyrrellii in the distance. 


40 


The rate of movement of transverse dunes was 
calculated by Hermesh (1972) by excavating plants 
of Tanacetum huronense var. floccosum, mea- 
suring their annual growth, and using a lee slope 
angle of 30-32°. He estimated that between 1967 
and 1971 one of the dunes he measured advanced 
36-70 cm per year and a second dune advanced 25 
cm per year. 

The importance of vegetation to the formation 
of transverse dunes is a subject of controversy. 
Cooper (1958) stated that wherever unidirectional 
wind is acting upon a heavy accumulation of sand 
unencumbered by vegetation transverse dunes will 
be formed. Other authors have argued that vege- 
tation is essential for maintenance of transverse 
dunes because this type of dune is essentially 
unstable and, without stabilization, will be con- 
verted into barchan or longitudinal dunes 
(Enquist, 1932; Bagnold, 1941). Their argument 
may be valid where the supply of sand is small but, 
where the supply of sand is great, transverse dunes 
are distinct and can maintain their individuality as 
they move forward. 

Hermesh (1972) recognized two kinds of trans- 
verse dunes of the freely moving type based on 
their dominant vegetation. He called those that 
reach heights of about 12 m “birch dunes” 
(Figure 33) and 3-6 m high “willow dunes” 
(Figure 21). He thought that the different forms 
and growth habits of these plants were responsible 
for the forms and sizes of the dunes. The sparse 
vegetation we have seen on them, however, shows 
little stabilizing influence. At most, it may modify 
a dune’s shape by giving it a more gentle crest and 
a less pronounced slipface. Transverse dunes may 
be formed, in fact, in the absence of vegetation 
(Cooper, 1958). We prefer, therefore, to consider 
the willow and birch dunes merely as parts of a 
continuum of variation among dunes and their 
vegetation. 


Precipitation Ridges 

Prominent on the perimeters of the large dune 
fields is a dune form that Cooper (1958) has 
referred to as a precipitation ridge. When a 
moving dune meets vegetation, the velocity of the 
wind is reduced and the sand piles up to form a 
ridge with a leeward slipface. In general, the ridge 
will be about as high as the vegetation is tall. 
Vegetation is not essential, however, for the for- 
mation of a precipitation ridge. Such ridges occur 
where a dune field is moving into a lake, river, or 
marsh vegetation as well as where forest is encoun- 


4] 


tered. Given sufficient sand and wind, the ridge 
continues to advance, its slipface inundating and 
burying the vegetation. The best defined and most 
conspicuous precipitation ridges are, of course, 
those invading forests (Figure 15). They reach 
heights of at least 12 m above the floor of the 
invaded woodland. 

At the inland perimeter of all of the larger dune 
fields, but most conspicuous on the eastern and 
southern sides, there are active precipitation 
ridges. Old, stabilized precipitation ridges occur 
occasionally just outside the present areas of 
active dunes (Figure 59), but long continuous 
ridges are not known any distance south of the 
large fields. This suggests that these active dune 
fields may not have extended further inland than 
they do at the present time or that their old 
precipitation ridges have been reworked and ob- 
scured by parabolic dunes. 

Aerial photographs usually show the margins of 
the dune fields invading forest as relatively sharp 
lines. In detail, however, the lines are somewhat 
scalloped, with slipfaces usually convex to lee- 
ward, but sometimes concave, particularly where 
a stream or river is eroding the front. The forward 
convex bulges have led David (1977) to suggest 
that they are really the advancing fronts of para- 
bolic dunes, but it seems to us that the variation 
from convex to concave could as easily be ac- 
counted for by the prevailing variation in the 
heights of vegetation being invaded. 


Other Sand Features 

Not as prominent as the oblique ridge and 
transverse dunes, but perhaps more important in 
terms of their areal extent, are the sand hillocks, 
sand sheets, and rolling dune topography. Some 
of these features may be early stages of oblique 
and transverse dunes, but most may pass through 
a cycle of aggradation and degradation without 
assuming an easily characterizable dune form. 

Sand Hillocks. Small sand accumulations, sel- 
dom over 0.6-1 m high, that form around or in 
the lee of small obstructions such as large cobbles, 
boulders, individual plants, or small groups of 
plants, are called sand hillocks. In the absence of 
these obstructions they are sometimes found as 
low lens- or shield-shaped dunes. In ground plan 
they may be more or less streamlined with nar- 
rowing “tails” or “tongues” extending downwind 
(Figure 22), or nearly circular and shallowly 
dome-shaped. Terms used for them in the litera- 
ture are “tongue,” “cushion,” “microdune,” or 


99 «66 


Figure 22. Hillock dunes in a dune slack in the Maybelle River sand dunes. Winds blow through the 
trough-like slack and build up small dunes in the lee of clumps of Hudsonia tomentosa and 
grasses. 


Figure 23. Area of rolling dunes in the William River dune field. 


42 


“minor” dune. Hermesh (1972) used “minor” 
dunes for the ones he saw in our area, while Smith 
(1978) called them “phytogenic” dunes. Though 
most of those seen in the Athabasca area are 
phytogenic, many are formed by other small 
obstructions or they may appear as shallow lens- 
shaped mounds without any obvious obstructions. 
Another term, “embryonic dune,” is sometimes 
used, but this implies that they are the beginning 
stages in the development of larger dunes, which 
may or may not be the case. In the large dune 
fields, where there is an abundance of blowing 
sand, they are most likely to be ephemeral. In 
marginal situations they may be early, though 
possibly ephemeral, stages of stabilization. 

Sand Sheets. As the term implies, these are 
merely thin covers of sand distributed more or less 
evenly over flat-lying or gently sloping surfaces; 
usually on gravel pavements (Figure 45). They are 
common in the central parts of the large dune 
fields. 

Rolling Dune Topography. Hermesh (1972) 
described and mapped large areas of what he 
called “rolling dunes” (Figure 23). The largest 
areas are in the eastern and southeastern parts of 
the William River field, in approximately the east- 
ern half of the Thomson Bay field, and south of 
Yakow Lake in the MacFarlane River dunes. 
Lesser areas are south of Beaver and Wolverine 
Points. His description was as follows: “These 
dunes form a gently rolling landscape devoid of 
shrubs or trees. Their height ranges from 0.5 to 
12m. Mature dunes are up to 750 m longand 75 m 
across. Crests are rounded, forming broad, almost 
flat tops. The slopes are never steeper than 10-12°” 
M@eemesn, 1972, p. 115). And “... they forma 
series of parallel oblong ridges, the long axis of 
which was aligned N35-44° W among the dunes 
near the William River, and between N40-—60° W 
among the Yakow Lake dunes. The alignments 
coincide with those of the longitudinal and trans- 
verse dune in the same areas” (Hermesh, 1972, 
pp. 118-119). 

Hermesh stated that these dunes formed a 
genetic sequence leading to the large oblique ridge 
dunes in the William River field. He described 
them in four types according to size, from heights 
of 0.5 m up to about 12 m, and also according to 
the density of their herbaceous vegetation, which 
he believed determined their form. He thought this 
vegetation was responsible for their rounded tops 
and gentle slopes. He noted that on the higher 
dunes slipfaces were formed, presumably because 


43 


the gradually thinning vegetation was less effective 
there. He stated “There is no abrupt change 
between the rolling and longitudinal dunes. All 
gradations from low rolling to large longitudinal 
dunes are found. Fifteen to twenty m high dunes of 
an intermediate type commonly occur as isolated 
examples among fields of lower rolling dunes” 
(Hermesh, 1972, p. 126). 

In the Yakow Lake area Hermesh associated 
rolling dunes with the transverse type. In this area 
they have alignments paralleling this type and 
have a “distinctly steeper east slope” (Hermesh, 
1972, p. 119). Onthe same page he associated them 
also with precipitation ridges, saying that they 
often form behind the latter as they advance over 
forests. In the small dune areas at Wolverine Point 
he mapped only rolling dunes, though we found 
well-formed transverse dunes there, with steep 
slipfaces. 

His rolling dunes are indeed abundant where he 
mapped them in the William River and Thomson 
Bay fields. His analysis rests heavily upon their 
being truly phytogenic and on the assumption that 
all or nearly all of their plants germinated in damp 
to wet sand in dune slacks and then grew up 
through the sand as the latter accumulated to form 
the dunes. However, we have found some taxa 
that clearly had germinated far above the slacks, 
and appeared to have had only ephemeral effects 
on the sand movement. Further, we have seen one 
or another of the dune willows on the rolling 
dunes. Some of the high oblique ridge dunes have 
rounded tops in the complete absence of vege- 
tation and some of the lower rolling dunes show 
incipient slipfaces. 

It has already been pointed out that the high 
dunes in the William River field probably owe 
their form and orientation to the interplay of 
northeastly and westerly winds. We suggest that 
the rolling dunes may be formed by the same 
opposing winds, which are here less effective and 
may be orientated in various directions. 

Smith (1978, p. 42) used Hermesh’s term, “roll- 
ing dunes,” as a catch-all for the, “vast area of the 
dune fields which lack dunes of classical or 
distinctive shape.” David (1977), who studied the 
Athabasca dunes only from aerial photographs, 
seems to have sensed this confusion of forms. He 
sought to rationalize it by a combination of the 
formation of parabolic dunes and an associated 
“embroidery” pattern. 

With our present knowledge of the dune forms 
and of the winds that produce them we are unable 


Figure 24. A gravel pavement ridge in the William River dune field. The sun is reflecting off the polished 
faces of the ventifacts that form the gravel pavement. 


Figure 25. View north across a barren plain covered with gravel pavement in the William River dune field. 
Oblique ridge dunes appear on the left and in the distance. 


44 


% 
Fekse: 
ers 3 
ae 


ae 

> 

he = See 
eRe Ae 


Figure 26. Ridge.of unsorted boulders, gravel, and sand near the southern edge of the Thomson Bay dune 


field just east of Little Gull Lake. 


to confirm or deny Hermesh’s or David’s analyses 
of these dunes. We use the term “rolling dune” as 
Smith used it as a catch-all for a multiplicity of 
forms which present essentially the same habitat 
for plants — that of active windblown sand. 


Aeolian Residual Features 


Gravel Pavements 

The deflation of material containing gravels too 
large to be moved by wind leads to the formation 
of a lag deposit that we are calling gravel pavement 
(Figures 24 & 25). Other terms have been applied 
to this feature: desert pavement (Bagnold, 1941), 
gravel plain (Holm, 1960), and pebble covered 
deflation surfaces (Smith, 1978). Since our area 
is neither a true desert nor always a plain, and 
since Smith’s expression is cumbersome, we are 
using the term gravel pavement. 

In the Lake Athabasca area, gravel pavements 
typically consist of a single layer of gravel over 
sand that may or may not contain coarser grains 
and scattered gravel. In some pavements the layer 


45 


of gravel is up to two to five cm deep, and in others 
it may consist of a range of coarse materials from 
pebbles and cobbles up to boulders one meter in 
diameter. This diversity in pavement surfaces is 
related to the origin of the coarse materials which 
can be traced to (1) glacial and fluvial deposits that 
were reworked by water in postglacial Lake Mc- 
Connell and later by wind, and to (2) unmodified 
glacial deposits that have been worked by wind 
into a lag concentrate. 

On the present shore of Lake Athabasca there is 
much variation in gravel beaches, but all of those 
that we have examined consist of a layer of gravel 
more than one stone thick. It is possible that some 
of the pavements with a deep layer of gravel 
overlying sand originated as a beach deposit, but it 
is unlikely that pavements with a single layer of 
stones originated in this way. 

In most gravel pavements the distribution of 
gravel on the surface is more compatible with the 
action of wind and gravity than with lake action. A 
transect across a gravel pavement ridge near Little 
Gull Lake showed a crest with a mixture of sand 


Figure 27. Polished and faceted ventifacts on a gravel pavement. 


and gravel to a depth of 10 cm overlying sand that 
contained occasional pebbles. From just below the 
crest of the ridge to the foot of the slope the 
pavement covered sand that lacked coarse inclu- 
sions. It is assumed that the crest represented 
glacial till that was worked by wind to yield a lag 
concentrate. Some of the coarse materials were 
moved downslope through the action of wind and 
gravity, probably assisted by frost action, to their 
present position overlying pure sand. The ability 
of wind to move gravel was shown in several places 
where pebbles up to 3 cm in diameter were 
overlying moss mats or charcoal layers. In each 
case there was a gentle slope from the source of the 
coarse materials to the pavement. 

Near the southern edge of the Thomson Bay 
dunes is a prominent morainal feature consisting 
of unsorted boulders, gravel, and sand (Figure 26). 
The substrate between the boulders consists of a 
mixture of gravel and sand to a depth of 35 cm. 
Downslope from this deposit, however, the sur- 
face is covered by a single layer of gravel overlying 
a sand matrix more than 50 cm deep containing 
only occasional coarse inclusions. This ridge is 
thought to be a drumlin which was incompletely 


46 


reworked by wave action on the receding shore of 
Lake McConnell and then was deflated by wind 
and gravity during the past 500-700 years (see 
radiocarbon dates). 

Gravel pavements prevent the wind from mold- 
ing the sand but they do not prevent the removal of 
the fine fraction from the surface. The deflation 
that takes place leads to a flattening of the surface 
much as occurs in the dispersal of sand mounds by 
strewing gravel on them (Lettau & Lettau, 1969). 

All of the major dune areas south of Lake 
Athabasca contain gravel pavements. In the 
William River dunes the oblique ridge dune field is 
located on a more or less flat gravel pavement 
(Figure 25). The southern and western portions of 
the Thomson Bay dunes support gravel pavements 
ona variety of topographic features from ridges to 
small hills and gently undulating surfaces. Ridges 
parallel to the present shoreline covered with 
gravel pavements are exposed in the Wolverine 
Point dunes. In the MacFarlane River dunes, 
gravel pavements are common in the southern 
part of the area at elevations up to 305 m. In all 
areas pavements are often exposed in the slacks 
between dunes. 


Figure 28. Wet dune slack in the Maybelle River sand dunes. Numerous seedlings of jack pine and birch 
grow in this slack. A young tree of Betula papyrifera is growing on the slope in the 
foreground along with mats of Hudsonia tomentosa and small jack pine saplings. 


The pavement stones are often abraded and 
polished to form ventifacts (Figure 27). Some 
ventifacts are of the single-ridged type, having 
been worked on a single surface, others have two 
winderoded surfaces, and many are of the three- 
ridged dreikanter type. Mabbutt (1977) stated that 
ventifacts are less common than the literature may 
suggest and, except in certain exceptional areas, 
they characterize pavements of considerable age. 
Ventifacts have been produced and are still being 
produced in glacial outwash areas (Antevs, 1928 
cited in Cooke & Warren, 1973) and from Pleisto- 
cene gravel-mantled surfaces in Wyoming (Sharp, 
1949 cited in Cooke & Warren, 1973). South of the 
presently active sand dune areas, ventifacts were 
seen by our parties in the Wolverine Point area 
and south of the headwaters of Ennuyeuse Creek. 
Tremblay (1961) also reported ventifacts from a 
large area in northern Alberta and Saskatchewan 
(see above). The age of the ventifacts in the Lake 
Athabasca sand dunes is unknown but they were 
certainly cut and polished after or during the time 


47 


the postglacial lakes were draining. Provided our 
surface age calculations are approximately correct 
they would have been formed in about the last 
4200 years. 


Dune Slacks 

The flat interdunal areas or troughs between 
sand ridges are called dune slacks. This name was 
used by Tansley (1953), p. 861), who defined them 
as “damp or wet hollows left between dune ridges, 
where ground water reaches or approaches the 
surface of the sand.” Laing (1958, p. 214) used the 
term panne for similar feature that he described as 
“moist, flat surfaces, and blowout pond margins.” 
The moisture condition of dune slacks inthe Lake 
Athabasca sand dunes varies from standing water 
to dry sandy flats and gravel pavements. In some 
places the lowest level to which deflation takes 
place between dune ridges is determined by the 
water table and these places may hold small ponds 
or moist flats (Figure 28). If the base level of the 
slack is determined by a gravel pavement or by a 


Figure 29. Dry dune slack in the Thomson Bay dune field. The brownish, silty-clay soil is broken into 
irregular polygons and the cracks are filled with sand to about 25 cm. Few plants grow in this 
habitat except for scattered individuals of Deschampsia, Elymus, and Tanacetum. 


silty-sand hardpan layer the slack may be dry 
(Figure 29). The moisture level of slacks varies 
with the season and some that hold standing water 
in spring are dry during midsummer and may be 
moist again in the fall. Sand accretion may also 
influence the moisture condition of a dune slack. 
Sand may accumulate in a slack by general 
infiltration over the entire surface, thereby slowly 
raising its general level, or a dune front may invade 
the slack from its edge and rapidly modify the 
moisture characteristics of a part of the slack. 
Ranwell (1959) described the moisture regime of 
dune slacks and recognized a gradient from wet to 
dry. He noted that the extremes differ greatly in 
their floristic composition. Wet to moist dune 
slacks provide a good habitat for seed germination 
and seedling establishment (see below), and the 
flora of these slacks, consequently, is the richest of 
any of the dune habitats; dry slacks, on the other 
hand, have few species and are sparsely plant 
covered. 


48 


Wet to moist slacks are usually confined to the 
periphery of dune fields or to partially buried 
drainageways within them. Some dune fields, for 
example at Wolverine Point, do not seem to have 
wet or moist slacks except perhaps in the very 
early spring. 


Stabilized Aeolian Topography 


Aeolian topography has already been men- 
tioned in describing the lands adjacent to the open 
sand areas. This topography is widespread south 
of Lake Athabasca. Throughout this region there 
is a complex system of ridges, dunes, sandy plains, 
and muskeg, with occasional lakes, ponds, and 
shallow stream valleys. The studies by Sproule 
(1939), Tremblay (1961), and David (1981), dis- 
cussed above, treat certain phases of it, but ground 
exploration is much needed. If the general frame 
of reference used in the present paper is tenable, 
the whole system should have been developed 


mainly by shore processes and wind as the shore of 
Lake Tyrrell-McConnell retreated northward 
across the drift-covered plain of the Athabasca 
Sandstone. 

The only kinds of vegetation that now appear 
capable of stabilizing the sands are dry upland 
forests and wet lowland forests and meadows and, 
even in an otherwise forested landscape, such 
vegetation does not become established in the 
presence of high winds. We do not know when 
pine forests reached the shores of ancestral Lake 
Athabasca, but probably it was not until after the 
close of the xerothermic interval with its warm dry 
climate. It is possible, however, that gallery forests 
advanced down river valleys during this interval 
(see above). 

Some of the present more or less stabilized 
topography is clearly visible in the oblique aerial 
photograph shown in Figure 14. The view is 
northeasterly from a point 6.5-8 km southeast of 
Wolverine Point, with the mouth of MacFarlane 
River at the upper right corner of the picture. The 
photograph shows a series of more or less parallel 
ridges running east and west and stopping at the 
shallow valley of the small stream that enters the 
lake at the next point east of Wolverine Point. The 
ridges fork in several places and show many gaps 
in their continuity. Other photographs, taken 
from points farther east, show the small stream 
with an eastern branch, flowing through a broad 
sand plain, with some ridges continuing eastward 
on its far side. The sand plain ends near the lake 
shore witha series of more recent shore ridges. The 
east-west ridges are composed mainly of sand, but 
some have gravel in them. They are extensively 
blown out, so that in many places they have 
become merely ranges of sand hills. The blowouts 
tend to be orientated diagonally to the trend of the 
ridges, like those described above nearer the shore 
of the lake. Ventifacts were found near the top of 
one of these hills, apparently in place and with 
lichens growing on them. 

Between the east-west ridges in Figure 14 is a 
system of lobate ridges generally trending north 
and south. Though variously curved, most are 
convex eastward. On the ground these ridges 
proved to have a well defined dune pattern with 
steep slopes facing east and long gentle slopes and 
tongues to the west. The position of the slip faces 
indicates that they were formed by westerly winds. 
Thus they have the form of parabolic dunes. They 
are so much altered by blowouts that in places they 


49 


can hardly be called ridges. Rather they are ranges 
of hills, some of which retain a ridge form. 

The long east-west ridges appear, in many cases 
(Figure 57), to be border ridges that mark the 
track of a parabolic dune. In some cases they may 
be moranic in origin (see above) as is a ridge south 
of the Thomson Bay dune field (Figure 6). We do 
not know whether the terrain southeast of Wol- 
verine Point was formerly in a large dune area. If 
so, the parabolic dunes did not form until after it 
became at least partly stabilized. 

The topography of the region south of the 
William River dune system suggests that it was 
once an open dune area that has since become 
stabilized and covered by forest. Further evidence 
was obtained along the winter road to Cluff Lake, 
about 3 km south of the present open dune field; 
where a gravel-covered surface containing venti- 
facts was exposed by road-building equipment. 
These ventifacts resemble those presently forming 
on the open gravel pavements. 


The Vegetation of the Sand Dune Region 


Plant habitats within the areas of actively 
blowing sand can be defined only on an ad hoc 
basis. Physical disturbance is virtually continuous, 
though its intensity varies widely in space and 
time. Migrating dunes override all other plant 
habitats that stand in their way. Small water 
bodies are filled with sand and their marginal 
zones of vegetation buried. Small drainage sys- 
tems are pushed into new channels or eliminated. 
Mature forests whether dry or wetland types, are 
killed and buried. Even those habitats that have an 
appearance of permanence, such as isolated stands 
of mature trees or dune slacks that contain well 
developed muskegs, may be highly modified or 
completely eliminated by the moving sand. The 
changes commonly occur within the life-spans of 
most of the plants that make up the vegetation 
found at a given point in time. 

Habitats in the more or less stabilized areas 
among the dune fields and immediately south of 
them are here defined by the vegetation found in 
them: forest (dry, intermediate, and wetland), 
muskeg shrub, muskeg meadow, grass-sedge 
meadow on sand, and aquatic vegetation. 

In describing the vegetation we have avoided 
the use of terms such as “community” and “asso- 
ciation” that imply a greater knowledge than we 
have about interrelationships among plants grow- 


ing together. For these terms we have substituted 
the word “assemblage.” For the term “dominant” 
we prefer to use “primary” for the species that 
characterize assemblages and make them physio- 
gnomically discernible from their neighbors. 

We have also avoided interpretations of biolo- 
gical succession in our discussions of vegetation. 
Our main reason is that we have no evidence of 
succession based on direct observation over time 
and it would serve no purpose to speculate from 
the spatial arrangement of plant assemblages. The 
problem posed by assumptions of succession in 
sand dune regions have been described by Olson 
(1958, p. 167) who wrote “Successions in the dunes 
are going off in different directions and have 
different destinations according to the many pos- 
sible combinations of independent variables which 
determine the original site and subsequent condi- 
tions for development....” Ranwell (1972, p. 194) 
in commenting on the succession diagrams that 
are commonly included in books on sand dune 
ecology, concluded that they “...not only over- 
simplify the many directions in which a particular 
community can develop, but tend to falsify the 
reality of the situation in the minds of student 
ecologists.” 


Actively Blowing Sand 


The vegetation of areas of actively blowing sand 
is made up of relatively few species, but they occur 
together in many combinations. The groupings 
that do occur are the result of many factors, 
including the chance establishment of species in 
habitats suitable for their germinationand growth, 
the length of time that the habitat was available for 
colonization, the rate of sand movement, and the 
way in which the individual species responds to 
sand infiltration, to burial, and to erosion. The 
cycle of sand accretion and the burial of plants 
followed by sand ablation and excavation of 
plants is repeated throughout the area of actively 
blowing sand. 

It has been observed that the dune flora de- 
creases in richness (number of species) from the 
borders of the large dune fields toward their 
centers. The largest numbers of taxa are in the 
dune slacks, particularly those with bottoms at or 
near the water table. Most of the moist to wet 
slacks are near the southern and northern margins 
of the large dune systems. Therefore, the decline in 
Species numbers toward the center of the fields is 
related in part to the absence of suitable slacks 


50 


which provide a seed bed for many species and to 
the intensity of sand activity there. 

Heights above the general level reached by 
vegetation on the active dunes are less than 15 m 
(Hermesh, 1972). On most of the dune surfaces 
above heights of 3-3.5 m the plants are widely 
scattered or absent. 

Related to the open dune habitat, and appar- 
ently with an even more rigorous environment, are 
the sand surfaces covered with gravel pavement. 
The vegetation of gravel pavement is very sparse 
and there are large areas that have no plants at all. 
Hills covered with gravel pavement may remain 
uncovered by sand for relatively long periods of 
time and here a sparse flora, consisting mainly of 
taprooted perennials, may occur for a while within 
a field of active sand dunes. 

About 30 species and infraspecific taxa of 
vascular plants were found growing on active 
dunes that were upwards of about | m high. Ten of 
these are endemic to the area. There appears to be 
a relationship between the sizes of the six dune 
areas we have studied and the distribution of the 
30 taxa. The largest of the areas (William River) 
contains 27. The Thompson Bay field has 24 and 
the MacFarlane River area has 20. The Wolverine 
Point dunes have 19, the Archibald Lake area 13, 
and the Maybelle River dunes 9. Parabolic dunes, 
represented in the above by the last three areas, are 
notably poorer in endemic plant taxa than are the 
larger dune fields. 

The flora of the Maybelle River sand dunes 
differs in other respects as well. Here the arctic 
taxa of the gravel pavements, Silene acaulis, 
Arabis arenicola, Carex maritima, and Armeria 
maritima ssp. interior, and the prominent slack 
plant, Juncus arcticus ssp. littoralis, which occurs 
in the Saskatchewan dunes are absent. Stellaria 
arenicola, otherwise known from sand dunes in 
Saskatchewan, is present. Chinnappa and Morton 
(1976) have shown that the characters that distin- 
guish this species appear at random throughout 
the range of S. longipes. While the occurence of S. 
arenicola in the Maybelle River dunes might be 
interpreted as evidence of a former connection 
between the Saskatchewan and Alberta dunes it 
more likely represents a more widespread occur- 
rence of this genotype than had previously been 
thought. 

On the other hand there are species in the 
Maybelle River sand dunes that are not known to 
occur in the Saskatchewan dunes. In the Alberta 
dunes Agropyron smithii, Koeleria macrantha, 


Salix lutea, and Tanacetum huronense var. bifa- 
rium occupy the same habitat as species in the 
Saskatchewan dunes with comparable ecological 
requirements. The latter two taxa are closely 
related to the Saskatchewan endemics Salix 
turnorii and Tanacetum huronense var. floc- 
cosum, respectively, and may represent the taxa 
from which the endemics have been derived. 

Some evidence for the origin and longevity of 
dune fields is suggested by the distribution of the 
endemics: 

William River sand dunes 

Thomson Bay sand dunes 


10 endemics 
10 endemics 


MacFarlane River sand dunes 9 endemics 
Wolverine Point sand dunes 4 endemics 
Archibald Lake sand dunes 4 endemics 
Maybelle River sand dunes 1 endemic 


The last three of these areas appear to be formed 
by parabolic dunes that probably originated as 
blowouts following fires in pine forests. If our time 
calculations are tenable, the pine forests did not 
come into the area until 4000-5000 years ago, 
while the large dune fields, fed by sand from the 
William and MacFarlane Rivers, are much older. 
The Wolverine Point dunes, may have had suffi- 
cient time to acquire their few endemics (4), while 
the more distant Maybelle River dunes, upwind 
from the large dune fields, got only one. The 
Archibald Lake dunes are probably younger than 
those at Wolverine Point but they are nearer the 
large fields, and downwind from them, and have 
also acquired four of the endemics. 


Seed Germination and Seedling Establishment 


Since the original vegetation of the active sand 
dune areas, if there was any, has been destroyed by 
sand activity, the present vegetation of these areas 
must be subsequent to the origin of the dunes. An 
understanding of the role of vegetation in the 
formation and stabilization of sand dunes must be 
based, in part, on a consideration of where and 
how seedlings become established in an area of 
active sand. 

During the growing season the conditions nec- 
essary for seed} germination and seedling estab- 
lishment are soil stability, adequate moisture, and 
nutrients (Laing, 1958; Ranwell, 1972). 


3The dry and indehiscent fruits of the Poaceae (caryopses) and 
the Asteraceae (achenes) are also generally referred to here as 
seeds. 


S54 


1. Stability. Seedlings of sand dune plants 
require a certain degree of stability for successful 
establishment, but they seem to do best in places 
where sand is slowly accumulating. Seedlings of 
some plants grow well on or at the base of lee 
slopes where there is a slow infiltration of sand or 
in dune slacks that are receiving a general light 
blanketing of sand. Wagner (1964, p. 94) empha- 
sized that it is places, “with moderate amounts of 
mobile sand that supports the greatest number of 
seedlings [of Uniola paniculata L.| and apparently 
provides optimal conditions for their survival and 
growth.” Seedlings are, however, intolerant of 
microerosion which reduces the available mois- 
ture, particularly to adventitious roots, and ex- 
poses them to physical damage (Laing, 1958; 
Huskies, 1977). 

2. Adequate moisture. Moist to wet dune slacks 
and seepage areas at the base of some lee slopes 
provide sites moist enough for seed germination. 
Those seeds that germinate on or at the base of lee 
slopes are usually buried up to 6 cm below the 
surface. The length of the coleoptile and mesoco- 
tyl (the first internode below the coleoptile) of 
some grasses is proportional to the depth of burial 
(Laing, 1958). The mesocotyl elongates raising the 
point at the base of the first leaf where adven- 
titious roots arise, to a position near the soil 
surface. 

Measurements made of mesocotyl length in 
some dune grasses at Lake Athabasca show that 
Agropyron smithii usually germinates about 3.5 
cm below the surface, Bromus pumpellianus may 
germinate at or near the surface or 2 cm below it, 
Calamagrostis stricta agg. germinates at about 2 
cm, and Deschampsia mackenzieana at about 0.5 
cm. 

3. Nutrients. The significance of nutrients to 
seedling establishment was not clear to Laing 
(1958), who thought that if they were important it 
might be because of their contribution to an 
increased rate of growth of seedling roots and 
consequently a more rapid absorption of water. 
Seedlings at the base of lee slopes often occur in 
the organic litter, but this may be due more to the 
concentration of propagules here by the wind or to 
the increased water-holding capacity of the soil 
than to increased nutrients. 

Observations were made on the germination 
and establishment of seedlings in the dune fields 
around the William River. In general, it was noted 
that moist to wet dune slacks provide suitable 
habitats for the germination of the disseminules of 


many dune taxa, including both herbaceous and 
woody plants. The lee slopes of dunes, particularly 
those receiving moderate amounts of sand, are 
suitable for the germination of the seeds of grasses 
and of a few herbaceous dicots, but seedlings of 
woody plants have not been seen in this habitat. 

1. Moist to wet dune slacks. Our observations 
show that open moist to wet slacks usually contain 
numerous seedlings of plants characteristic both 
of active sand habitats and the surrounding forests 
and muskegs (Figure 28). Seedlings of active 
sand dune plants that occur in dune slacks are: 
Agrostis scabra, Bromus pumpellianus, Des- 
champsia mackenzieana, Salix brachycarpa var. 
psammophila, S. planifolia ssp. tyrrellii, Betula 
spp., Ste/laria arenicola, Artemisia borealis, and 
Tanacetum huronense var. floccosum. 

Seedlings or gametophores of plants character- 
istic of stabilized forests and muskegs also occur in 
moist to wet slacks. These include: Polytrichum 
commune, P. juniperinum, Pogonatum_ § urni- 
gerum, Lycopodium inundatum, Picea glauca, 
Pinus banksiana, Carex aquatilis, Juncus brevi- 
caudatus, Salix bebbiana, S. planifolia ssp. 
planifolia, S. pyrifolia, Populus balsamifera, 
Betula glandulosa, B. neoalaskana, Orthilia se- 
cunda, Andromeda polifolia, Ledum groenlan- 
dicum, Vaccinium uliginosum, Empetrum nigrum, 
and Hieracium umbellatum. Some old slacks 
contain mature forest or muskeg vegetation and 
the entire flora must be subsequent to the devel- 
opment of such slacks, but all species were not 
seen as seedlings. 

2. Dry dune slacks. Few seedlings occur in dry 
dune slacks and only seedlings of Elymus mollis 
are common. Seedlings of Deschampsia macken- 
zieana and Tanacetum huronense var. floccosum 
were observed growing with Elymus on a silty- 
sand hard pan in a dry slack (Figure 29). Other 
grasses, including Agropyron smithii and Calama- 
grostis stricta agg., have been observed only as 
adults in dry slacks on hard pan, but their seeds are 
evidently able to germinate and establish in this 
habitat. Grasses are the most common plants in 
this habitat, but some herbaceous dicots notably 
Tanacetum are sometimes locally abundant and 
Armeria maritima ssp. interior was seen once in 
this habitat. 

3. Leeward slopes of sand dunes. Some plants 
have been observed as seedlings on the lee slopes 
of sand dunes, but whether they can survive 
throughout the year is in this habitat unknown. 
The taxa that are known as seedlings in this 


52 


habitat are: Agropyron smithii, Bromus pumpe- 
llianus, Calamagrostis stricta agg., Hudsonia to- 
mentosa, Artemisia borealis, and Tanacetum hu- 
ronense var. floccosum. More commonly, plants 
establish themselves in the organic litter at the 
base of lee slopes (Figure 30). Seedlings of the 
following taxa have been observed here: Agro- 
pyron smithii, Bromus pumpellianus, Deschamp- 
sia mackenzieana, Elymus mollis, Artemisia 
borealis, and Tanacetum huronense var. floccosum. 
It is possible that adult plants of these species 
growing on.the lee slopes and crests of active dunes 
have germinated on the dunes themselves or at the 
foot of lee slopes. Excavations made at the edge of 
a dune showed that caryopses of Agropyron 
smithii germinated in a silty-sand hard pan layer in 
a dune slack and the plants had grown through 10 
cm of sand. Further up the slope Calamagrostis 
stricta agg., that had germinated in the same hard 
pan layer, was growing through | m of sand. 
Woody plants, including Salix and Betula, do not 
seem to be capable of germination on active dunes 
and plants of those genera growing on the dunes 
(see below) must have germinated in a moist dune 
slack that was subsequently covered by a migrating 
dune. 

4. Gravel pavements. Seedlings of the following 
taxa were observed on a gravel pavement: Salix 
planifolia ssp. tyrrellii, S. silicicola, Silene acaulis, 
Armeria maritima ssp. interior, and Artemisia 
borealis. In the Thomson Bay dune field individuals 
of Arabis arenicola, Salix silicicola, and Silene 
acaulis were seen to be perched 0.8, 5, and 12 cm 
respectively, above the present gravel surface. The 
perched plants indicate that either the gravel 
pavement surface had been eroded between 0.8 
and 12 cm during the life of the plants or, more 
likely, that the plants germinated on a superficial 
sand layer that was subsequently removed. 

The gravel pavements seem to be unfavorable 
for seed germination and seedling establishment. 
Their dry condition throughout most of the grow- 
ing season and their exposure to winds may 
explain their sparse flora; but Silene acaulis and 
Armeria maritima ssp. interior are mostly restricted 
to this habitat. It is probable that their tap-root 
habit does not adapt them to grow on moving 
sand; but, in the laboratory, seeds of Ameria 
germinate readily and why seedlings of this taxon 
do not appear, at least, on moist dune slacks is 
difficult to explain. 

5. Open sand. Seeds rarely germinate on wind- 
swept, open sand surfaces and only Elymus 


iat ‘ 


* 
~< . ee aiid 
= 


x 


Figure 30. Base of the lee slope of a transverse dune in the Maybelle River sand dunes. Organic debris is 
trapped by Agropyron smithii in the foreground. Calamagrostis, Bromus, and Tanacetum 


huronense var. bifarium occupy the slope. 


mollis was observed to do so. Its caryopses 
germinated as they were being covered with sand 
moved by a northwesterly wind and the young 
seedlings were being uncovered by a subsequent 
northeasterly wind. It is unlikely that these plants 
could survive continued sand erosion and their 
survival depended on a change in wind direction. 

We have observed that dune slacks provide the 
main habitat for the invasion of plants into the 
active dune areas. The seeds of certain herbaceous 
plants, mainly grasses, are able to germinate and 
to grow on active dunes, but most of these plants 
also can become established in dune slacks and 
may grow up through migrating dune sand. 
Seedlings of woody plants are known only from 
moist to wet slacks. 

These observations agree with those of Cowles 
(1899), Ranwell (1972), Laing (1958), et al., in that 
they emphasize the importance of the dune slack 
habitat in the vegetation cycles on active sand. 
Plants undoubtedly have a significant influence on 
the formation of dunes and can modify their size 
and shape according to the growth behavior of the 


53 


colonizing taxa. However, it must be observed 
that, although plants can function as “dune- 
formers,” dunes can also be formed by non-living 
features of the landscape such as stones or out- 
crops or simply by the action of wind on sand. To 
refer to the sand dunes in the Lake Athabasca 
region as phytogenic is to overlook this fact. Just 
as important, however, is the recognition that even 
when plants do serve to accumulate sand and to 
modify the form of a dune, they are unsuccessful in 
this area in permanently stabilizing the sand. The 
force of the winds along the south shore of Lake 
Athabasca is great enough that even at a distance 
of 15 km or more from the lake shore wind is 
capable of moving sand more rapidly that the 
vegetation can arrest it. 


The Vegetation in Areas of Active Sand 


Although the conspicuous and interesting obli- 
que ridge and transverse dunes of the large dune 
fields command our attention, the most common 
dune features are the vast areas of sand sheets, 


Figure 31. Cushion dunes are formed by clumps of Deschampsia and Bromus on this gravel pavement 


in the William River dune field. 


rolling sand topography, and small hillock dunes. 
It is most appropriate, therefore, to begin our 
consideration of the vegetation of the active sand 
areas with a look at these features. 


Hillock and Cushion Dunes. 

Plants and other obstacles are able for a time to 
trap sand in the form of small dunes. The most 
common plants to accumulate sand in this way are 
the grasses Bromus pumpellianus, Festuca rubra 
ssp. richardsonii, Deschampsia mackenzieana, 
Calamagrostis stricta agg., and Elymus mollis 
(Figure 31). Scattered among the grasses may be 
individuals or small groups of other species cha- 
racteristic of the open, shifting dunes: Ste/laria 
arenicola, S. longipes, Artemisia borealis, Achil- 
lea lanulosa ssp. megacephala, and Tanacetum 
huronense var. floccosum. Most of these dunes are 
asymmetric in ground plan, with “tongues” direct- 
ed down wind. 

Lens-shaped “cushion” dunes, though they are 
occasionally barren, are usually formed by the 


54 


trapping of sand in herbaceous mat plants or by 
prostrate shrubs. They are most common in areas 
marginal to the large dune fields or in blow-outs in 
the adjacent forests. The species most effective in 
their formation are: Silene acaulis, Potentilla 
tridentata, Empetrum nigrum, Hudsonia tomen- 
tosa, Arctostaphylos uva-ursi, Vaccinium vitis- 
idaea, and V. uliginosum (Figure 22). In several 
localities xerophytic mosses and fruticose lichens 
replace the vascular plants: Po/ytricum commune, 
P. piliferum, Pogonatum urnigerum, and species 
of Stereocaulon, Cladina, and Cladonia. The 
cushion dunes commonly harbor a few species 
from the larger dunes, notably grasses and an 
occasional willow (e.g. Salix silicicola) or if they 
are near a Seed source, seedlings of pine and birch. 


Rolling Dune Topography. 

In the William River and Thomson Bay fields 
there are large areas of rolling dune topography. 
Toward the center of the dune fields herbaceous 
plants may sparsely cover these dunes while 


Figure 32. Transect of a transverse dune. The movement of the dune is from west to east. 


toward the perimeter of the fields Sa/ixand Betula 
are common (Figure 23). The vegetation of these 
dunes includes all of the plants of active sand 
dunes, such as: Bromus pumpellianus (often a 
primary species), Elymus mollis, Deschampsia 
mackenzieana, Calamagrostis stricta agg., Fes- 
tuca rubra ssp. richardsonii, Salix brachycarpa 
var. psammophila, S. silicicola, S. turnorii, S. 
planifolia ssp. tyrrellii, Betula glandulosa, B. 
neoalaskana, B. X sargentii, B. X utahensis, Hud- 
sonia tomentosa, Stellaria arenicola, S. longipes, 
Achillea lanulosa ssp. megacephala, Artemisia 
borealis, and Tanacetum huronense var. flocco- 
sum. 

The differences between herbaceous and shrub- 
by dunes are to be sought not in the dunes 
themselves but in the establishment requirements 
of the plants. Many of the herbaceous taxa have 
been observed to be capable of establishment on 
the surface of active dunes where moisture may be 
available only for a short time after a rain or in 
the form of dew. The woody plants, Salix and 
Betula, require a more continuously moist seed 
bed and relatively stable sand conditions such as 
prevail in a dune slack that lies at or near the water 
table. These different plant requirements appear 
to explain the gradients of poor to rich flora or 
from no plants to an herbaceous vegetation, then 
to a mixed woody and herbaceous vegetation, 
such as has been observed in the major active dune 
fields. These gradients are understandable in 
terms of the relatively greater exposure of the 
water table surface on the perimeter of the dune 
fields and the harsher environmental conditions 
that prevail in their centers, primarily in the form 
of windblown sand which abrades the plants and 
keeps the habitat unstable. 


Transverse Dunes. 

Within the active dune fields a cyclical pattern 
of vegetation establishment, burial, and reexposure 
is commonly observed. This process is not succes- 
sional in the sense of leading to a final stage or of 


55 


each “successive” vegetation that has a profound 
effect on the habitat, but rather it is cyclical. Most 
of the species involved become established in the 
dune slacks and what apparent change is observa- 
ble in the floristic composition from one “stage” to 
another is due to the length of time that the 
depression remains uncovered by a migrating sand 
dune and to the selective elimination of species as a 
dune invades the dune slack. A composite transect 
across a dune slack being invaded by a transverse 
sand dune will illustrate this process (Figures 32, 
33 & 20). 

Zone |. The assemblage of plants in the dune 
slack and at the foot of the slip face of a dune 
migrating into a dry depression in the Wolverine 
Point dunes consists of the following taxa: Bro- 
mus pumpellianus, Festuca rubra ssp. richard- 
soni, Deschampsia  mackenzieana, Elymus 
mollis, Calamagrostis stricta agg., Salix silicicola, 
Stellaria arenicola, Empetrum nigrum, Tanace- 
tum huronense var. floccosum, and Artemisia 
borealis.1f one were to name the primary species 
in this group, or at least the most characteristic, 
they would be in the genera Calamagrostis, Des- 
champsia, Bromus, and Elymus. Most of the 
plants in the assemblage are on the lower slopes 
of the slip face or just at its base on the more 
nearly level ground. Those on the slip face are 
being covered slowly by sliding sand. Some of 
those at the base are on small hillocks of sand 
while others have spread more widely. Most of the 
taxa are rhizomatous or have decumbent spread- 
ing stems, while Deschampsia is caespitose. 

In a dune slack with an exposed water table, but 
one which is not flooded throughout the year, 
zone | may take ona different aspect. Moist to wet 
slacks provide an excellent seed bed for many 
species (see above) and, if sufficient time elapses 
before the slack is invaded by a migrating dune, a 
young forest may develop (Figure 33). Sometimes, 
however, a dune moves across the slack so soon 
after the water table is exposed, and the sand 
moves so rapidly, that no plants occur on the lee 
slope of the invading dune (Figure 34). 


56 


In the MacFarlane River dune field a young 
forest in a moist slack was observed being invaded 
by dunes (Figure 33). In this case the older part of 
the depression (zone 1) was covered by a shallow 
layer of sand and the seedlings of a number of 
additional species had become established. Here a 
young forest developed consisting of saplings of 
Pinus banksiana, Betula papyrifera, and an occa- 
sional individual of Larix laricina. The ground 
was covered by a sparse moss mat of Polytrichum 
with Sphagnum compactum, Aulacomnium pa- 
dustre, and Drepanocladus uncinatus along with 
the vascular plants Calamogrostis stricta agg., 
Carex abdita, Juncus arcticus ssp. littoralis, Hud- 
sonia tomentosa, Potentilla tridentata, Empetrum 
nigrum, Artostaphylos uva-ursi var. coactilis, 
Vaccinium uliginosum, Hieracium umbellatum, 
and Solidago decumbens var. oreophila. 

Zone 2. The sand moving up the long gentle 
slope from zone 6 1s carried over the top of the 
dune and deposited in zone 2. This zone, ona dune 
invading a dry slack, may be devoid of plant life. 
The herbaceous plants that may have been rooted 
in the dune slack are usually not able to withstand 
the rapid accumulation of sand in this zone and 
soon succumb. If the dune, however, is invading a 
moist-wet slack in which woody plants have 
become established, shrubs may occupy this zone 
because of their ability to withstand the rapid sand 
accummulation (Figures 33 & 20). 


Figure 33. Panorama of a large dune slack in the 
MacFarlane River dune field. The 
slack is being invaded by two dunes. 
The foreground dune is moving from 
the west northwest (away from the 
viewer), the dune in the middle distan- 
ce is moving from the south southeast 
(from right to left), and the windward 
slope in the upper left is moving from 
the west (to the left). In the slack, 
which has remained undisturbed for 
some time, a young jack pine-birch 
woods is being buried by sand. Birch 
trees survive on the lee slope and the 
crest of the dune on the left, and Salix 
planifolia ssp. tyrrel/lii appears on the 
crest of the dune in the foreground. 
Seedlings become established in the 
slack around the perimeter of the 
forest, especially in a moist area near 
the base of the windward slope. 


Figure 34. Transverse dune about 15 m high invading a moist dune slack near Yakow Lake. The rate of 


advance of the dune appears to be so rapid that the plants growing in the slack fail to grow 


up through the lee slope. 


mone 3. Ihe lee side of the top of the dune 
(Figures 33 & 20) may be sparsely plant-covered. 
Bromus pumpellianus and Deschampsia macken- 
zieana are usually the most abundant plants in this 
zone; Elymus mollis and Festucarubrassp. richard- 
sonii are common; and Stellaria arenicola, Tana- 
cetum huronense var. floccosum, Artemisia 
borealis, Salix planifolia ssp. tyrrellii, and Betula 
papyrifera are occasional. 

In some places (Figure 33) a well developed 
thicket may occupy the lee slope and crest (zone 3) 
of an active dune. This vegetation may include a 
number of willows (Salix silicicolaand S. turnorii) 
and birches (Betula glandulosa, B. neoalaskana, 
B. occidentalis, B. X sargentii, B. X utahensis, and 
B. winteri) in addition to the previously mentioned 
species. 

The vegetation on transverse dunes in the 
Maybelle River dunes of Alberta is physiogno- 
mically similar to that on the Saskatchewan dunes 
but the species are different. The most common 
species on the crests and lee slopes (zone 3) of the 
dunes in this region are: Agropyron  smithii, 
Bromus pumpellianus, Calamagrostis stricta agg., 


57 


Festuca rubra ssp. richardsonii, and Tanacetum 
huronense var. bifarium; of less importance are: 
Koeleria macrantha, Hudsonia tomentosa, and 
Artemisia borealis. In some places shrubs or small 
trees may appear, including, most commonly, 
Salix lutea, S. planifolia ssp. planifolia and Betula 
papyrifera, B. X sargentii, and B. X winteri. 
Zone 4. The deflation zone on the windward 
side of the dune crest is occupied by scarcely any 
living plants. It is notable for small hummocks of 
sand (Figure 35) held together by the remains of a 
group of grasses that appeared in zone 3. The 
hummocks are capped by tangles of dead leaves 
and stems. Digging in them revealed dead roots 
and stem bases of the grasses, with only a few dead 
roots that had penetrated below the general level 
of the dune surface. This suggests that although 
the plants in zone 3 appeared to be thriving, the 
eastward advance of the dune crest will place them 
on its windward side where they are subject to 
erosion and ultimately will be killed. Only the sand 
immediately around their roots would be held for 
a time forming hummocks as the general surface is 
eroded. As the erosion continued on the windward 


Figure 35. Irregular hummocks mark the remains of Elymus and Calamagrostis left behind on the 
windward side of a transverse dune. 


Figure 36. Transverse dune on the right invading (from right to left) a dry, gravel covered dune slack in the 
MacFarlane River dune field. Skeletonized jack pine, killed during a previous sand invasion, 
appear on the windward slopes in the foreground. 


58 


Figure 37. Birches being undercut and killed as their dune is reduced by ablation in the Thomson 
Bay dune field. 


slope of the dune, the hummocks become smaller 
and finally disappear completely. There is here the 
Suggestion that the assemblage in zone 3 in 
temporary and superficial, with no deep penetra- 
tion of the dune sand. In other places where woody 
plants occupy this zone the penetration is deeper, 
presumably to the surface of the original dune 
slack; but even in these cases the vegetation 
appears to have only a small effect on the rate of 
movement or the form of the dune. It may serve 
only to increase, somewhat, the deposition of sand 
on the upper part of the lee slope, and to lengthen 
the slope to the top of the slip face. 

Zone 5. Where the surface wind again becomes 
effective and the dune slack approaches or reaches 
its lowest level, skeletal remains of old forests are 
uncovered (Figure 36) and individuals of birch 
and willow may remain perched on hillocks of 
sand (Figure 37). 


59 


Oblique Ridge Dunes. 

The high oblique ridge dunes have plants only 
on their lee slopes and sometimes on the secondary 
dunes that radiate from their windward slopes. No 
plants occur on or near the dune crests and only 
rarely do any plants extend more than one half 
way up the lee slopes; plants usually occur less 
than 3 m above the base of the dune (Figure 38). 
Only herbaceous plants occur on these dunes 
including: Deschampsia mackenzieana, Elymus 
mollis, Bromus pumpellianus, Calamagrostis 
stricta agg., Festuca rubra ssp. richardsonit, Tana- 
cetum huronense var. floccosum, and Artemisia 
borealis. Seedlings of Deschampsia, Elymus, Bro- 
mus, and Artemisia were observed to be growing 
at the foot of the lee slopes. At the ends of the 
oblique ridge dunes, where the sand is less deep 
and the slope is less steep, seedlings of Bromus 
have been observed and presumably other herba- 
ceous species could also become established here. 


Figure 38. Lower part of the lee slope of an oblique ridge dune in the William River dune field. 
Tanacetum, Calamagrostis, and Bromus grow on the slope. The oblique ridge dune in the 
background has two prominent peaks. 


| Ee i SE 


Figure 39. Parabolic dune. Plan view and cross-section subdivided into zones. 


60 


Parabolic Dunes. 

The parabolic dune cycle is similar in many 
respects to that described for the transverse dunes 
and its lee slope is comparable to the precipitation 
ridge that forms on the perimeter of the major 
dune areas where sand is actively invading the 
surrounding vegetation. 

The vegetation of the parabolic dunes can best 
be described by a composite example based on 
dunes studied in the southerly parts of William 
River and Thomson Bay fields. The cross-section 
of a parabolic dune is illustrated in Figure 39. The 
lee slope may be invading Pinus banksiana forest, 
Picea mariana muskeg or open wetland vegetation. 
The dune crest may stand between 6 and 9 m above 
the surface of the vegetation that it is invading. If 
trees impede the movement of wind and sand, the 
dune crest builds to a higher level than if no 


obstacle were present. If the obstacle is removed, 
for example by fire, the dune crest blows out and 
moves ahead more rapidly, seemingly impeded 
only by Betula, which may grow as a shrub 
through its crest, and mats of Hudsonia which 
attempt to recolonize its slopes. Both of these 
impediments are soon overcome, however, and 
the survivors bypassed. 

Along the lee slope (zone |), certain species have 
the ability to grow up through sand that accumu- 
lates on the dune face before they are overwhelm- 
ed. If the sand is invading a pine forest (Figure 15), 
Pinus banksiana trees may survive burial for 
a while, and Arctostaphylos uva-ursi, Betula 
occidentalis, B. papyrifera, B. X sargentii, B. Xx 
utahenses, B. X winteri, Geocaulon lividum, Le- 
dum groenlandicum, Vaccinium uliginosum, and 
V. vitis-idaea may grow on the advancing dune 


Figure 40. Lee slope of a parabolic dune invading a Picea mariana muskeg northeast of Little Gull Lake. 
The muskeg shrubs, Chamaedaphne calyculata (foreground), Andromeda polifolia, and 
Vaccinium uliginosum, grow up through the sand as it advances. They are associated with the 
dune plants, Calamagrostis stricta agg., Tanacetum huronense var. floccosum, and Stellaria 
arenicola, which have the ability to germinate on dune slopes. 


Figure 41. Hudsonia tomentosa is a primary species on the windward edge of a large parabolic dune west 


of Maybelle River. 


slope. None of these species, with the exception of 
Betula, is able to withstand moving sand for long 
and all are soon overtopped and killed. 

If a muskeg is being invaded (Figure 40), 
Andromeda polifolia, Chamaedaphne calyculata, 
Ledum groenlandicum, L. palustre var. decum- 
bens, Vaccinium myrtilloides, and V. uliginosum 
may occupy the dune slope, frequently appearing 
on the slope as high as 3 m above the forest floor. 
These are often in association with the dune plants 
Achillea lanulosa ssp. megacephala, Artemisia 
borealis, Calamagrostis stricta agg., Festuca rubra 
ssp. richardsonii, Stellaria arenicola, Tanacetum 
huronense var. floccosum, and others. These dune 
species are not a part of the muskeg flora itself but 
they become established on the moist sand at the 
base of the lee slope, or, in the case of Tanacetum, 
on the dune slope itself. These dune plants grow up 
through the sand along with the few muskeg 
species as the dune advances. The survival of these 
individuals in the face of sand accumulation will 
depend upon their ability to produce roots nearer 
to the surface and on the rate of slope movement. 


62 


In some cases, where the slope is devoid of 
vegetation, we assume that the rate of sand 
movement was too rapid for the plants to adjust. 
The center of a parabolic dune (zone 2) is 
actively eroding. No plants grow there, and it is 
studded with the remains of trees that were killed. 
In some places a depression exposing the surface 
of the water table may be seen to windward of the 
erosional area. Here a variety of species, particu- 
larly those associated with the active dunes, may 
become established, including: Bromus pumpel- 
lianus, Calamagrostis stricta agg., Festuca rubra 
ssp. richardsonii, Hudsonia tomentosa, Juncus 
arcticus ssp. littoralis, Salix brachycarpa, S. bra- 
chycarpa X pyrifolia, S. pyrifolia, S. silicicola 
(rare), S. planifolia ssp. tyrrellii, Betula spp., and 
Tanacetum huronense var. floccosum. With the 
exception of Hudsonia and Calamagrostis, these 
species do not occur in the pine forests that may 
eventually invade and occupy this kind of site. 
The usual pattern of plant invasion along the 
windward margin of the parabolic dune (zone 3) 
(Figure 41) involves mats of Hudsonia tomentosa 


Figure 42. Border ridge extending from the southwestern tip of the parabolic dune west of Maybelle River 
(cf. Figure 53). The gentle sand slopes are sparsely covered by open grown Jack pine, Hudsonia 
tomentosa, Polytrichum spp., and fruticose lichens. 


(primary), Arctostaphylos uva-ursi, Artemisia bo- 
realis, Festuca rubra ssp. richardsonii, Empetrum 
nigrum, and Polytrichum commune, together 
with seedlings of Pinus banksiana and Betula spp. 
The first trees of Pinus banksiana to grow at the 
edges of the stabilized area (zone 4) are character- 
istically of a bushy, open-grown form. In the forest 
that follows, this form is accompanied by slender, 
less profusely branched trees (Figure 46). The 
forests and other vegetation that become estab- 
lished on stabilized parabolic dune surfaces will be 
discussed below. 

The border ridges that trace the path of move- 
ment of parabolic dunes across the landscape are 
very sparsely covered by Pinus banksiana and an 
almost continuous moss mat of Polytrichum spp. 
(Figure 42). The only other important species is 
Hudsonia tomentosa. Between the patches of 
open sand may occur occasional individuals of 
Festuca saximontana, Salix bebbiana, Betula pa- 
pyrifera, Prunus pensylvanica, Arctostaphylos 
uva-ursi, and small patches of fruticose lichens. 

The simple parabolic dune situation that has 
been discussed often is made more complex by the 
formation of blowouts in the forest on the wind- 


ward side and the possible development of these 
blowouts into parabolic dunes. The dune crest 
may be broken through by a blowout or by the 
removal of impeding trees and a secondary para- 
bolic dune may become superimposed on the main 
dune. In places where parabolic dunes may cover 
an extensive area, such as at Wolverine Point and 
Maybelle River, the open sand area is so large that 
it contains transverse dunes, rolling dunes, and 
other features of the major dune fields. The 
vegetation of these features is similar to that 
described above. 


Gravel Pavements. 

The plains and rolling hills of sand that are 
covered with a veneer of stones are sometimes 
sparsely covered with plants, but large expanses 
are devoid of plant life (Figures 24 & 25). Those 
species that do occur on the gravel pavements are 
widely scattered and include: Carex maritima 
(rare), Salix brachycarpa var. psammophila, S. 
silicicola, S. turnorii, S. brachycarpa X turnorii, 
Silene acaulis, Arabis arenicola, A. lyrata, Armeria 
maritima ssp. interior, Artemisia borealis, and 
Tanacetum huronense var. floccosum. Evidently 


; 
« wy a 


Figure 43. Hummocks of Si/ene acaulis on a gravel pavement in the Thomson Bay dune field. A plant of 
Salix silicicola is visible at center right. 


these flowering plants are able to germinate and 
become established on the gravel pavements, but 
seedling are rarely observed (see above). 

The mosses Polytrichum juniperinum and P. 
piliferum form large mats in some areas. On stones 
and boulders grow the lichens Acarospora sma- 
ragdula, Buellia lacteoides, Evernia mesomorpha, 
Hypogymnia physodes, Lecanora badia, L. chry- 
soleuca, L. polytropa, Lecidea auriculata, Parme- 
lia disjuncta, P. stygia, Rhizocarpon riparium, 
Rhinodina sp., and Umbilicaria hyperborea. 
Other lichens such as Stereocaulon alpinum and 
S. condensatum may form cushions on thin sand 
layers on the gravel. Some saxicolous lichens on 
the gravel pavements appear as unattached va- 
grant lichens (Weber, 1977), and form pebble-like 
balls that le free on the pavement surface. This 
unusual morphological modification is known in 
the Lake Athabasca area only from the gravel 
pavements in the sand dunes surrounding the 
William River and occurs in Cetraria hepatizon, 


64 


Lecanora chrysoleuca, L. melanopthalma, Par- 
melia stygia, and Xanthoparmelia centrifuga. 
Some gravel pavement surfaces appear to be 
relatively stable and hummock-forming plants 
such as Silene acaulis tend to build up hillock 
dunes on them (Figure 43). The occurrence of 
perched plants, however, indicates that deflation 
of the surface occurs as sand is winnowed from 
between the stones or as shallow sand layers are 
eroded. In addition to the perched plants of Arabis 
arenicola and Silene acaulis, noted above, a 12- to 
14-year old plant of Salix brachycarpa was obser- 
ved perched about 15 cm above the present surface 
indicating a deflation rate of the gravel surface, or 
of a shallow sand layer, of about | cm per year. 
In places where there is a slow infiltration of 
sand over the gravel-covered surface the mosses 
Pogonatum urnigerum, Polytrichum juniperi- 
num, P. piliferum, and Rhacomitrium canescens 
may form mats (Figure 44), sometimes accom- 
panied by Si/ene hummocks and by Salix silicicola. 


Figure 44. A gravel pavement composed of gravel and a mat of Polytrichum juniperinum. The pebbles 
moved onto the moss mat by downslope creep. 


In areas where the sand has built up into shallow 
dunes the tap-rooted plants of the gravel pave- 
ments, Silene acaulis, Arabis arenicola, A. lyrata, 
and Armeria maritima ssp. interior, do not occur; 
but, rather, an assemblage of sand dune plants, 
including Festuca rubra ssp. richardsonii, Stella- 
ria arenicola, and Empetrum nigrum, predomi- 
nate (Figure 45). 

There are extensive areas of sandy-gravel pave- 
ment in the southwestern part of the William 
River dunes and in the southern part of the 
MacFarlane River dunes where colonization by 
Empetrum, forming mats and hummocks, is ac- 
companied by open stands of Pinus banksianaand 
Betula X sargentii (Figure 46). Empetrum nigrum 
covers the shallow sand as mats or, as sand 
accumulates on the mats, as small hummocks. 
These hummocks are accompanied by other hum- 
mock-forming species, Hudsonia tomentosa and 
Potentilla tridentata. Interspersed among these 
hummocks are Bromus pumpellianus, Calama- 
grostis stricta agg., Festuca rubra ssp. richard- 
sonii, Salix silicicola, Stellaria arenicola, Prunus 
pensylvanica, Vaccinium uliginosum, Achillea la- 


65 


nulosa ssp. lanulosa and ssp. megacephala, Arte- 
misia borealis, and Tanacetum huronense var. 
floccosum. Pinus banksiana may slowly invade 
the area over a period of time and individuals 
ranging from seedlings about five years old to trees 
4 m tall and 18 cm in diameter at the base may be 
seen. Here Pinus grows in bushy habit typical of 
open-grown plants (Figure 46). Under trees devel- 
op mats of Stereocaulon alpinum, S. glareosum, 
Cladonia amauracraea, C. uncialis, and Cetraria 
nivalis. Betula occidentalis, B. X sargentii, and B. 
X winteri also invade the stabilized Empetrum- 
moss mat as individuals or as small populations. 

The generally flat Enpetrum-moss mat cover- 
ed surface may be broken by small blowouts and 
dunes. One such dune, standing 1.8 m above the 
surface, supported a typical sand dune flora 
consisting of Bromus, Festuca, Calamagrostis, 
Hudsonia, Stellaria, Artemisia, and Tanacetum. 
The absence of Empetrum mats on the dune 
probably reflects its inability to grow under condi- 
tions of rapidly accumulating sand which would 
lead to dune formation. When a shallow sheet of 
sand covers an area, populations of Ca/amagros- 


Figure 45. Shallow sand dune trapped by hummocks of Empetrum nigrum and the grasses Bromus, 
Calamagrostis, and Festuca overlying a gravel pavement in the MacFarlane River dunes. 


tis, Deschampsia, and Festuca tend to predomi- 
nate over those of Empetrum, which can survive 
only for a short time by modifying its growth toa 
hummock or a mat of branches that protrude to 
the surface. 

Another kind of gravel-covered surface occurs 
as old raised beaches covered with flat stones 
derived from the prevailing thin-bedded sands- 
tone bedrock of the region, though occasionally 
other rocks, probably derived from glacial tills, 
are represented. These low ridges are nearly 
devoid of vegetation. Occasional individuals of 
Arabis lyrata, Artemisia borealis, and Silene 
acaulis were found rooted in sand among the 
stones. Arabis and Artemisia occur also on sand 
beaches at the lake shore, but Silene has thus far 
been seen only in the dune areas. 


Dune Slacks and Buried Drainageways. 

The moisture regime of dune slacks ranges from 
open water to dry sand or gravel pavements (see 
above), and the vegetation varies accordingly. Dry 
slacks support few taxa, including those grasses 
and herbaceous dicots able to germinate there. In 


66 


moist to wet slacks a rich flora may develop that 
includes not only dune plants but also plants of the 
surrounding forests and muskegs. 

In slacks with exposed water tables (Figure 28), 
but which are not flooded throughout the year, the 
entire surface may become covered with seedlings. 
In the early stage of development the vegetation is 
graminoid and may be dominated by Agrostis 
scabra, Deschampsia mackenzieana and Juncus 
arcticus ssp. littoralis associated with Calama- 
grostis stricta agg., Festuca rubra ssp. richardsonii, 
Carex abdita, Juncus alpinus, Salix brachycarpa 
var. psammophila, S. silicicola, S. turnorii, S. 
planifolia ssp. tyrrellii, and Stellaria arenicola. 
The mosses Drepanocladus exannulatus, Pohlia 
drummonadii, P. nutans, and Polytrichum com- 
mune may appear also at this stage along with 
seedlings of Pinus banksiana, Betula papyrifera, 
and B. X sargentii. A tree cover may develop if 
sufficient time elapses before the dune slack is 
invaded by a sand dune. 

In the southern part of the William River dune 
system there is a complex of dunes and depres- 
sions that appears to represent partly buried 


Figure 46. Open jack pine-birch stand on a gravel pavement in the William River dune field. Betula 
neoalaskana, B. occidentalis, and B. X sargentii are co-primary with Pinus banksiana. 
Mats of Empetrum nigrum and Polytrichum spp. are scattered between the trees. 


drainageways (Figure 47). These drainageways 
occur as moist to wet, or sometimes dry, depres- 
sions located between active dunes. One small area 
at the southwestern edge of the dune system was 
studied. Here the sand was moving southward, 
invading a Pinus banksiana forest and a Picea 
mariana muskeg and forming a precipitation 
ridge. A profile through a portion of the dune and 
depression complex is illustrated in Figure 48. The 
precipitation ridge on the right and the dune 
invading from the left (zones | & 8) both supported 
thickets of Betula neoalaskana, B. papyrifera, and 
B. X sargentii. Of all the dune species, the birches 
are best able to withstand burial by deep sand 
deposits. Even those plants that survive, however, 
will be killed eventually as the dune moves past 
them and ablation of the sand occurs (Figure 37). 


67 


To windward of the precipitation ridge was a low 
rolling dune (zone 2). It was primarily covered by 
Calamagrostis stricta agg., which occurred with 
Bromus pumpellianus, Festuca rubra ssp. richard- 
sonii, Carex aquatilis, Juncus arcticus ssp. littora- 
lis, and Tanacetum huronense var. floccosum. No 
seedlings were seen on this dune. On the windward 
side of the low dune was a dune slack (zone 3) that 
was in the process of being filled with sand and was 
not conspicuously wet. This depression was cover- 
ed by a mat of Polytrichum commune and Pogo- 
natum urnigerum. Growing in this mat were: 
Calamagrostis stricta ayg., Carex aquatilis, Juncus 
arcticus ssp. littoralis, Salix brachycarpa var. 
psammophila, S. planifolia ssp. tyrrellii, Betula 
glandulosa, B. papyrifera, Potentilla tridentata, 
Empetrum nigrum, and Achillea lanulosa ssp. 


Saeed iii 


eo 


ee 


Figure 47. Oblique aerial view of a wet drainageway in the William River dune field. 


megacephala, seedlings of Pinus banksiana, Carex 
aquatilis, Artemisia, Tanacetum, and several gras- 
ses. 

Invading the depression was a shallow sand 
dune (zone 4) covered with Calamagrostis stricta 
agg., Carex aquatilis, Juncus arcticus ssp. litto- 
ralis, Salix brachycarpa var. psammophila, S. 
pyrifolia, S. planifolia ssp. tyrrellii, Silene acaulis 
f. athabascensis (very rare), Tanacetum huron- 
ense var. floccosum, and young plants of Pinus 
banksiana. Shrubs of Betula glandulosa were 
buried by about 2-4 cm of sand. There were 
no evident seedlings on this dune, the windward 
slope of which was being eroded by the wind. 
Some plants were being eroded out and killed. 

Still further windward is another dune slack 
that was seasonally wet (zone 5). The primary 
vegetation in this slack was a mat of Pogonatum 
urnigerum and Carex aquatilis along with Betula 
glandulosa and Lycopodium clavatum, L. inun- 
datum, Pinus banksiana, Agrostis scabra, Salix 
bebbiana, S. pyrifolia, S. planifolia ssp. tyrrellii, 
Betula papyrifera, Drosera rotundifolia, Andro- 
meda_ polifolia, Chamaedaphne — calyculata, 


68 


Ledum groenlandicum, Vaccinium uliginosum, V. 
vitis-idaea, Epilobium angustifolium, and Tana- 
cetum huronense var. floccosum. 

In zone 6, where sand was infiltrating the dune 
slack, there were numerous young sporophytes of 
Lycopodium inundatum, seedlings of Agrostis 
scabra, Juncus brevicaudatus, Salix brachycarpa 
var. psammophila, S. pyrifolia, S. planifolia ssp. 
tyrrellii, Betula glandulosa, Orthilia secunda, and 
young gametophores of Pogonatum. 

The dune invading this depression (zone 7) was 
covered by Calamagrostis stricta agg., Carex 
aquatilis, and Tanacetum which apparently were 
growing up through the dune. The large dune 
(zone 8) advancing toward the series of dunes and 
depressions supported only Betula papyrifera and 
B. X sargentii on its crest. 

The complex dune and depression pattern that 
has just been described cannot be understood in 
terms of a simple vegetational succession pattern. 
Seedlings of almost all of the available species are 
able to grow in the wet or moist dune slacks, 
particularly in those parts of the slacks onto which 
sand is slowly infiltrating. Species typical of the 


Figure 48. Profile of a buried drainageway just north of Ennuyeuse Lake. The sand is moving from 
left to right. 


moving sand, in such genera as Achillea, Tana- 
cetum, and the dune grasses, can also become 
established on shallow. sand dunes. The dune slack 
habitat is localized and ephemeral, and it is subject 
to invasion by sand, which precludes the forma- 
tion of a stable vegetation. Even when the dune 
slacks are large and have a vegetation that resem- 
bles that of stabilized sites, the active dunes 
surrounding them will eventually invade them and 
destroy the vegetation. 


The Vegetation on Stabilized Aeolian 
Topography 


There are two major forest types in the Atha- 
basca sand dune region. Jack pine (Pinus bank- 
siana) is the primary tree on the excessively 
drained sands and gravels of ancient beaches, 
stabilized dunes, sandy-gravel ridges, and sand 
plains. At the other end of the moisture gradient is 
wetland muskeg forest, primarily of black spruce 
(Picea mariana) and tamarack (Larix laricina). 
Intermediates between these types, which might be 
called “mesophytic,” are extremely variable and 
widespread, but they occupy, collectively, a relati- 
vely small fraction of the land surface. The two 
major habitats, dry and wet, are usually rather 
sharply defined. The boundaries between these 
habitats, however, are much blurred by the 
vegetation, which is higly variable, fragmentary, 
and difficult to define. Probably this is due to 
two main factors. One is the prevalence of forest 
fires, the incidence and effects of which are 
discussed elsewhere in this paper. The disturbing 
influence of fire is greatest, of course, in pine 
woods, but in very dry seasons wetland forests 
may also be burned. The second factor, and 
probably the more significant, is the wide moisture 
tolerance of the principal species. Usually, but not 
always, mixtures of jack pine, white and black 


69 


spruce, and paper birch occur at sites where the 
water table is just below the surface or on small 
local flood plains along streams. White spruce is 
usually considered the most mesophyftic tree in the 
region, but it also flourishes on the driest sand 
ridges. Black spruce is characteristic of wetland 
muskegs where jack pine and white spruce usually 
are not found. But it is also abundant on high 
sandstone bluffs near Poplar Point where it grows 
in cracks in the flat-lying rock. Jack pine grows on 
the driest sand hills and also thrives in low ground 
where the water table is very near the surface. 
Paper birch, though not abundant in the region, is 
found in mesophytic sites and also on active 
dunes. 


Forests on Dry Sites 

The most common forest type growing on 
stabilized dunes and on the sandy till plains south 
of Lake Athabasca is open jack pine-lichen forest 
(Figure 49). When young, these forests are 
dense but as the trees mature they become widely 
spaced and park-like, with very little upright shrub 
growth and with a ground cover of fruticose 
lichens, xerophytic mosses, a few scattered herbs, 
and occasional mats of trailing shrubs. In some 
places pine is the only vascular plant. In other 
places there are occasional white spruce or paper 
birch and one or two other species usually inclu- 
ding Hudsonia tomentosa, Empetrum nigrum, 
Arctostaphylos uva-ursi, and Vaccinium myrtil- 
loides. If only a small area is studied, such as one 
quarter of a hectar, the flora is deceptively meager, 
but collections in many such areas have yielded 
upwards of 60 kinds of vascular plants. The 
following list could doubtless be enlarged: 

Equisetum arvense, Lycopodium annotinum, 
L. dendroideum, Juniperus communis, Picea 
glauca, P. mariana, Pinus banksiana, Agrostis 
scabra, Calamagrostis stricta agg. Festuca rubra 


ae 


pi SI Rte 
> td : > 
a [5 tee 
* oe oe pete 
= = S 


Figure 49. Jack pine-lichen forest on sand. 


ssp. richardsonii, F. saximontana, Oryzopsis 
pungens, Dicanthelium acuminatum, Poa glauca, 
Carexvabdita,wC. aenea, C. Siccata; C> tonsa, 
Juncus arcticus ssp. littoralis, Maianthemum ca- 
nadense, Cypripedium acaule, Populus balsami- 
fera, P. tremuloides, Salix planifolia ssp. plani- 
folia, S. scouleriana, Alnus crispa, Betula 
papyrifera, Comandra umbellata ssp. pallida, 
Geocaulon lividum. Drosera routundifolia, 
Saxifraga tricuspidata, Amelanchier alnifolia, 
Potentilla tridentata, Prunus pensylvanica, Rosa 
acicularis, Rubus idaeus ssp. sachalinensis, Sorbus 
scopulina, Empetrum nigrum, Hudsonia  to- 
mentosa, Lechea intermedia var. depauperata, 
Epilobium —angustifolium, Aralia  nudicaulis, 
Cornus canadensis, Arctostaphylos uva-ursi var. 
coactilis, Chimaphila umbellata ssp. occidentalis, 
Ledum groenlandicum, Vaccinium myrtilloides, 
V. vitis-idaea, Apocynum androsaemifolium, 
Melampyrum  lineare, Linnaea_ borealis ssp. 
americana, Campanula rotundifolia, Artemisia 
borealis, Hieracium umbellatum, Solidago 


decumbens var. oreophila, S. nemoralis var. 
longipetiolata; lichen mats commonly composed 
of Cladina arbuscula, C. mitis, C. rangiferina, 
C. stellaris, Cladonia amaurocraea, and C. gra- 
cilis; and the mosses Polytrichum juniperinum 
and P. piliferum which often form pure mats or 
are intermixed with lichens. 

Pine forests burn repeatedly and some record of 
the burns in an area may be recorded in the 
existing stands of trees. Burns sometimes appear 
on aerial photographs as a “meadow-like” vege- 
tation which may occur over large areas. One such 
area, studied in 1935, proved to be a nearly pure 
stand of small jack pine about 12 to I5 years old 
(0.5 m tall, 2 cm in diameter); single trees or small 
dense stands of trees about 40 years old (2-2.5 m 
tall, ca. 5cm in diameter); and a third class of trees 
about 130 years old (ca. 8 m tall, 22 cm in 
diameter). The trees shown in (Figure 49) are 
in the oldest age class. From these data it was 
evident that a major fire went through the area 
about 1920. As usually happens, some trees sur- 


vived as individuals or small stands. Trees of the 
40-year age class appeared after a fire that occur- 
red about 1895. The oldest trees date from about 
1805, which was also probably a time of fire. 

In all of the pine forests observed, very few trees, 
to judge by their diameters and probable growth 
rates, could have been much older than 130-150 
years. From this we suggest that few areas along 
the south shore of Lake Athabasca have escaped 
being burned for much longer than 150 years, and 
that any one spot may have been burned over 
about 20 times in the last 3000 years, which is 
probably as long as forests have been in this area. 

The jack pine is particularly prolific at seeding 
after a fire because its cones ordinarily remain 
closed for many years, but open when subjected to 
intense heat. Germination is almost immediate, 
leading to a dense cover of seedlings (Figure 6). 
Along the winter road to Cluff Lake, skirting the 
western edge of the sand dunes and heading south 
of Ennuyeuse Lake, the Pinus banksiana forest 
was extensively burned in about 1970. One burn 
had regenerated to three to five year old Pinus 
seedlings. The primary species in this vegetation 
were Agrostis scabra, Hudsonia tomentosa, and 
Carex tonsa, and Pinus seedlings. Associated with 
them was Carex aenea. Older, park-like stands 
commonly have an admixture of Populus tremu- 
loides, Betula papyrifera, Salix spp., and Vacci- 
nium myrtilloides. The ground cover in such jack 
pine stands is composed mainly of species of the 
fruticose lichens Cladonia, Cladina, Cetraria, and 
Stereocaulon. 

Well into the open William River dune field 
there are occasional patches of Pinus banksiana 
forest, some perhaps one kilometer wide and 
harboring many shallow ponds (Figure 48). 
Some of these stands appear to have been undis- 
turbed for a long time. The trees seem to be of all 
ages, from young seedlings to old decrepit trees. 
There are no remains of burned wood on the 
ground and no fire scars on the older trees. The 
ground surface is gently rolling and appears to be 
dune topography. It is mostly covered by a dense 
mat of the fruticose lichens characteristic of open 
pine forest and has an abundant growth of 
Vaccinium myrtilloides. Some sand dune grasses 
including Bromus pumpellianus, Deschampsia 
mackenzieana, and Elymus mollis occur in these 
forests. In the low spots are large numbers of 
muskeg shrubs and black spruces. It is not certain 
whether these forests are relics of old woodland 


7] 


missed by the advancing sand or whether they 
have developed on dunal topography that has 
been partially deflated. 

An exception to the predominance of jack pine 
on dry sites is its replacement by Alberta white 
spruce (Picea glauca var. albertiana) in a few situ- 
ations. A traveller moving along the south shore of 
Lake Athabasca could easily get the impression 
that the country is covered with white spruce, for it 
forms most of the forest visible from the lake 
(Figures 7 & 11). A short walk inland shows that 
the spruce is confined to a few ridges (sometimes 
to only one) immediately above the shore where 
blowouts are frequent. At the western margin of 
the small dune area just southeast of Wolverine 
Point, there is a zone of blowouts in which the par- 
tially stabilized areas are occupied by park-like 
Alberta white spruce stands. Subtending them to 
westward are the usual dry pine woods on stable 
sands. The blown-out tops of ridges in the country 
a few kilometers southeast of Wolverine Point 
also support white spruce on the western edges of 
diagonal blowouts. Where the sand is being 
moved actively, the open woods of old jack pine 
are being removed; here the trees becoming bush- 
like, with many twisted or dead branches. That the 
spruce is only a temporary resident is shown by the 
fact that the forest on the more completely 
stabilized ridges is almost invariably of jack pine. 
This is further supported by the occurrence of one 
decrepit old spruce in a stand of young pines on a 
stabilized ridge. Its occurrence around blowouts 
suggests that it may be able to stand more physical 
disturbance than jack pine. 


Forests on Intermediate (“Mesophytic”) Sites 

Combinations of species from wetlands and 
from the driest sites occur in seemingly infinite 
variety in and around the dune fields. Low places 
in the pine forests on the stabilized dune surfaces, 
most of them probably relicts from dune slacks, 
retain some soil moisture through all or most of 
the summer. Here the woods have a rather thin 
shrub layer of species drawn from the muskegs or 
damp sandy shores including: Ledum groenlan- 
dicum, Kalmia polifolia, Andromeda polifolia, 
Chamaedaphne calyculata, and Vaccinium uli- 
ginosum. Herbs seen in such places are Calama- 
grostis canadensis, Spiranthes romanzoffiana, 
and Lycopus uniflorus. Black spruce (Picea 
mariana) may also occur here. 

Vegetation located in an intervale between 
parallel bands of large, parabolic dunes just south 


of Yakow Lake contains a mature, closed forest of 
Picea mariana, Pinus banksiana, and Betula pa- 
pyrifera. Associated with these trees are Goodyera 
repens, Alnus crispa, Geocaulon lividum, Empe- 
trum nigrum, Arctostaphylos uva-ursi, Ledum 
groenlandicum, and Vaccinium vitis-idaea. 

A still more mesophytic phase of the pine forest 
is seen occasionally, usually at the bases of the 
steep slopes of stabilized dune slipfaces and on the 
lower slopes of the adjoining dunes. Here Picea 
mariana and Betula papyrifera are sometimes 
abundant and become primary species in the 
assemblage. Common upright shrubs are A/nus 
crispa, Salix scouleriana, Viburnum edule, and 
Ledum groenlandicum. Empetrum nigrum, Arc- 
tostaphylos ura-ursi, and Vaccinium vitis-idaea 
are common trailing shrubs. Occasional herba- 
ceous species are Lycopodium annotinum, L. 
sitchense, Goodyera repens. Lathyrus ochro- 
leucus, Vicia americana, Cornus canadensis, Apo- 
cynum androsaemifolium, and Melampyrum li- 
neare. 

Intermediate combinations are found also to- 
ward the dry end of the moisture gradient. Along 
the shores of Lake Athabasca and at the mouth of 
the MacFarlane River is a series of old, stabilized 
beach ridges parallel to the shoreline. On one of 
these ridges a forest of Picea glauca and Pinus 
banksiana, estimated to be 150 years old, was 
observed. It contains a flora relatively rich for the 
area, including some species that are usually 
restricted to the active sand dunes. The flora 
included: Agrostis scabra, Bromus pumpellianus, 
Elymus mollis, Festuca rubra ssp. richardso- 
nii, Festuca saximontana, Poa pratensis, Carex 
abdita, C. tonsa, Juncus arcticus ssp. littoralis, J. 
vaseyi, Salix planifolia ssp. planifolia, Betula 
glandulifera, B. neoalaskana, Stellaria arenicola, 
Arabis lyrata, Amelanchier alnifolia, Potentilla 
norvegica, P. tridentata, Prunus pensylvanica, 
Rosa acicularis, Rubus idaeus ssp. sachalinensis, 
Empetrum nigrum, Hudsonia tomentosa, Epilo- 
bium angustifolium, Pyrola elliptica, Arctosta- 
Phylos uva-ursi, Vaccinium uliginosum, Artemi- 
sia borealis, Hieracium umbellatum, and Tana- 
cetum huronense var. floccosum. 

Perhaps the most mesophytic forest we have 
seen in the dune region is that limited to small local 
flood plains along streams such as Ennuyense 
Creek and the William and MacFarlane Rivers 
(Figures 55 & 60). The Alberta spruce (Picea 
glauca var. albertiana) is the primary species, and 
individuals reach greater heights and diameters 


TZ 


than elsewhere in the region. Alaska paper birch 
(Betula neoalaskana) is often associated with it as 
a primary species. Common shrubs are: A/nus 
crispa, Sorbus scopulina, Rosa acicularis, Ledum 
groenlandicum, Vaccinium myrtilloides, V. uli- 
ginosum, and V. vitis-idaea. It usually has a 
ground cover of woodland mosses, Aulacomnium 
palustre and Ptilium crista-castrensis, and scat- 
tered here and there the following herbs: Lycopo- 
dium annotinum, L. complanatum, L. dendroi- 
deum, Cypripedium acaule, Goodyera repens, 
Geocaulon lividum, Epilobium angustifolium, 
Aralia nudicaulis, Cornus canadensis, Chimaphi- 
la umbellata ssp. occidentalis, Trientalis borealis, 
and Linnaea borealis ssp. americana. Anyone 
familiar with the boreal American spruce forest 
will recognize elements that are widely distributed 
across the northern part of the continent. This 
forest, however, contains species of both eastern 
and western phases of the boreal forest: from the 
east, Cypripedium acaule, Vaccinium myrtilloi- 
des, and Aralia nudicaulis; from the west: Betula 
neoalaskana, Sorbus scopulina, Chimaphila um- 
bellata ssp. occidentalis, and the western variety of 
Picea glauca var. albertiana. 

At the center of Little Gull Lake an island 
covered by a closed mesophytic forest of Picea 
mariana has apparently escaped burning or other 
disturbance. It has reached a stage of development 
not observed elsewhere in the area. Only two 
species of vascular plants, Ledum groenlandicum 
and Vaccinium vitis-idaea are associated with the 
black spruce. These shrubs occur as scattered 
individuals in a deep carpet of mosses. Of the 
twelve species of mosses collected in the area the 
most common are Pleurozium schreberi, Ptilium 
crista-castrensis, Orthodicranum montanum, Di- 
cranum polysetum, and Pohlia nutans. The island 
is fringed with boulders which appear to relate it to 
the till-covered terrain to the south side of the lake 
more than to the stabilized sand dune covered 
landscape to the north. 


Wetland Vegetation 

Between Cree Lake and Lake Athabasca, on the 
long gentle slope of Athabasca Sandstone that is 
mantled by sandy glacial tills, are wide expanses of 
wetland interspersed with dry sandy deposits. The 
water table in this mantle is relatively high, held up 
by the sandstone or by permanently frozen sub- 
soil. Drainage northward and northwestward is 
variously interrupted by aeolian topography and 
by elongated ridges with an east-west, north- 


south, or northeast-southwest orientation. Un- 
drained or poorly drained depressions in which 
the water table is at or near the surface have 
produced the wetland vegetation. Ponds and small 
lakes are frequent. 

Our knowledge of the wetlands is confined to 
those we have seen in and around the Lake 
Athabasca dunes, supplemented by studies in 
other parts of the Mackenzie drainage basin. The 
region between the Lake Athabasca dunes and 
Cree Lake is botanically unexplored. 

Efforts to standardize the description and 
nomenclature of wetland habitats and vegetation 
in the boreal forest regions of the world are legion. 
None has proved acceptable much beyond the 
limits of the locality or region for which it was 
conceived, and even.there agreement has never 
been complete. Probably this is due to the extreme 
variation, in both time and space, exhibited by 
these vegetations and their habitats. With modern 
knowledge of ecotypic variation within species, 
and of the instability of physical habitats, stan- 
dardization can hardly be expected. In this paper 
we shall not attempt to fit our descriptive units and 
analysis of wetland vegetation into units derived 
elsewhere and shall use the simplest possible 
conceptual frame-work on which to describe and 
analyze them. 

The common name for most of the wetlands in 
northern Canada and Alaska is “muskeg,” an 
Indian word for a mossy bog, particularly one 
with hummocks or tussocks on the surface. It is 
applicable to nearly all of the wetlands in the 
region with which we are dealing. Exceptions are 
on the sandy or stony shores of Lake Athabasca, 
on the shores of some shallow sandy ponds, and in 
damp to wet short-lived slacks among the active 
dunes. In these exceptions the moss substratum is 
lacking or nearly so. 

Muskeg vegetation usually has three forms: 
forest, shrub, and grass-sedge meadow, all of 
which freely intergrade. They are most easily 
identified when seen at a distance as “zones” 
around the shores of lakes and ponds. As such 
they are purely physiognomic units, distinguished 
by the forms of their primary species. In shallow 
basins without standing water, the whole surface 
may be covered by any one of the three forms. If 
ponds or small lakes are present, a fourth, off- 
shore zone of aquatic plants, may or may not be 
present. 

The vegetation zones around the shores of lakes 
and ponds are commonly interpreted as deve- 


73 


lopmental stages in a “succession” from open 
water to forest. If such a succession actually occurs 
it requires that the water levels remain fairly 
constant over long periods of time, with no major 
physical disturbance of the shores by fire or wind- 
blown sand or the opening of new drainage 
channels. In this region, where all of these factors 
are or have been active, the assumption of suchan 
orderly succession appears gratuitous. It is fully as 
reasonable to assume that all of the species came 
into their zones at approximately the same time 
and survived in those segments of the moisture 
gradient most suitable to their requirements. 


This is suggested by the vegetation of the dune 
slacks which, by definition, are more or less 
temporary. The moisture supply is determined by 
the extent of deflation with respect to the water 
table, and the time available is determined by the 
rate of dune movement. Under these circum- 
stances, any one or any combination of the 
muskeg or sandy shore assemblages can be found 
in the dune slacks in each of which all or most of 
the primary species must have arrived at about the 
same time. Some biological succession may occur 
in the slacks but, if so, its vegetational results must 
be fragmentary and indeterminate. 

Muskeg Forest. The primary trees in the mus- 
keg forests are black spruce ( Picea mariana) and 
tamarack (Larix laricina) (Figure 50) occurring 
together or separately. The hummocky moss 
ground cover is different combinations of Callier- 
gon stramineum, Dicranum polysetum, Helodium 
blandowii, Orthodicranum montanum, Pleuro- 
zium schreberi, Pohlia nutans, Ptilium crista- 
castrensis, Sphagnum magellanicum, and S. re- 
curvum. Shrub growth is extremely variable in 
density and species composition from place to 
place, most of it drawn from the following group 
of species: Salix bebbiana, S. planifolia ssp. 
planifolia, Myrica gale, Alnus crispa, Ribes hud- 
sonianum, R. triste, Rosa acicularis, Empetrum 
nigrum, Ledum groenlandicum, L. palustre var. 
decumbens, Andromeda _ polifolia, Chamaeda- 
phne calyculata, Vaccinium myrtilloides, V. uligi- 
nosum, V. vitis-idaea, Oxycoccus quadripetalus, 
and Viburnum edule. Herbaceous species include: 
Lycopodium annotinum, L. selago, Equisetum 


fluviatile, E. sylvaticum, Calamagrostis canaden- 


sis, Carex chordorrhiza, C. pauciflora, C. tris- 
perma, Calypso bulbosa, Spiranthes romanzo- 


ffiana, Geocaulon lividum, Drosera rotundifolia, 


Coptis trifolia, Potentilla palustris, Rubus cha- 
maemorus, Epilobium ciliatum ssp. glandulosum, 


Figure 50. Picea mariana muskeg on the shores of Little Gull Lake. A muskeg shrub vegetation appears 


on the shore in the foreground. 


E. leptophyllum, Cornus canadensis, Orthilia se- 
cunda, Pyrola asarifolia, P. elliptica, P. virens, 
Lysimachia thyrsiflora, Trientalis borealis ssp. 
latifolia, and Menyanthes trifoliata. 

As in the dry pine woods flora this is a 
composite list. In any one locality only a few 
species may be found. Among the shrubs, Empe- 
trum and the Ericaceae are most common. The 
most common herbs are Equisetum, Lycopodium, 
Geocaulon, Cornus, Orthilia, and Pyrola. The 
appearance of other kinds of trees in the wetland 
forest adds to the floristic variability. More meso- 
phytic species such as Betula papyrifera, Picea 
glauca, Populus balsamifera, and even Pinus 
banksiana, are occasionally found with the black 
spruce and tamarack, suggesting the wide habi- 
tat versatility in most of the forest trees of the 
region. 

Muskeg Shrub. The ground cover in muskeg 
shrub vegetation is a hummocky mat of mosses in 
which the primary vascular plants are upright or 


74 


decumbent shrubs (Figure 50). The water table 
is near the surface, or above it in depressions 
among the moss hummocks. Species from the wet 
meadows commonly appear in these places. Picea 
mariana, Larix laricina, and Betula papyrifera 
appear as seedlings or small trees, individually or 
in scattered clumps, or “peninsulas” from neigh- 
boring muskeg forest. The shrubs that give this 
vegetation its form are: Salix pedicellaris, Betula 
glandulosa, Chamaedaphne calyculata, Ledum 
groenlandicum, and Vaccinium uliginosum. 
Other vascular plants that occur in this vegetation 
are: Scheuchzeria palustris var. americana, Tri- 
glochin maritimum, Carex aquatilis, C. limosa, C. 
rostrata, Eriophorum chamissonis, E. graci!2, E. 
vaginatum ssp. spissum, Salix athabascensis, S. 
planifolia ssp. planifolia, S. pyrifolia, Myrica gale, 
Sarracenia purpurea, Drosera anglica, D. linearis, 
D. rotundifolia, Potentilla palustris, Kalmia poli- 


folia, and Menyanthes trifoliata. These plants 


grow commonly in hummocky mats of Sphag- 


a 


‘+ imee 4 a 
3 ‘ wy +t, aw - Ne Fis : 


z 


er; 


on 


Figure 51. Muskeg grass-sedge meadow on the shores of Ennuyeuse Lake. A jack pine woods occupies 


the higher ground in the background. 


num, often with small pools of water between the 
hummocks, with sedges, grasses, and other plants 
found more frequently in the muskeg meadows. 
Our records, combined from many observa- 
tions, show that the herbaceous flora of the shrub 
muskegs contains at least 46 kinds of plants, of 
which 16 were found only in the shrub vegetation. 
Overlapping habitat tolerances are suggested by 
the distribution of the remaining 30. Fourteen 
were found also in the muskeg forest, five were 
also in the muskeg meadows (see below), and 11 
were found in all three of these vegetations. 
Muskeg Grass-sedge Meadow. The moss and 
humus mat is thinner and less continuous, and 
there is more free water on the surface in muskeg 
grass-sedge meadow than in the shrub muskeg 
(Figure 51). Shrubs, if they occur, are scattered 
or reduced to a few trailing or decumbent species. 
The plants that give form to this type are rushes, 
grasses, and sedges, mainly the latter. The species 
content varies greatly from one meadow to the 
next, so that generalization becomes difficult or 
impossible; but the following species are often 
found in this habitat: Equisetum fluviatile, Spar- 


75 


ganium minimum, Scheuchzeria palustris var. 
americana, Triglochin maritimum, Calamagrostis 
canadensis, Carex aquatilis, C. brunnescens ssp. 
sphaerostachya, C. chordorrhiza, C. diandra, C. 
lasiocarpa ssp. americana, C. limosa, C. michau- 
xiana, C. oligosperma, C. magellanica ssp. irrigua, 
C. rostrata, Eleocharis palustris, Eriophorum 
chamissonis, E. gracile, Rhynchospora alba, R. 


fusca, Scirpus hudsonianus, Calla palustris, Salix 


pedicellaris, Myrica gale, Betula glandulosa, Stel- 
laria crassifolia, Drosera anglica, D. rotundifolia, 
Potentilla palustris, Epilobium leptophyllum, 
Andromeda _polifolia, Chamaedaphne calycu- 
lata, Lysimachia thyrsiflora, Menyanthes trifo- 
liata, Utricularia cornuta, and Galium trifidum. 
Grass-Sedge Meadow on Sand. This vegetation 
differs from the muskeg meadow in having little or 
no substratum of humus or moss (Figure 52). 
Its habitat is widespread, although it is highly 
localized and covers a relatively small total area. 
The composite vascular flora of the grass-sedge 
meadow on sand is one of the largest in the region, 
with approximately 80 species, no less than 17 of 
which were not seen in any other habitat. This 


vegetation occurs at the margins of some lagoons 
near the shore of Lake Athabasca, on sandy shores 
or bars along streams and on the shores of inland 
ponds or small lakes that have sand bottoms. All 
of these sites are notable for seasonal or longer- 
term fluctuations in moisture supply, or for phy- 
sical instability of the sand. 

Primary species found at one place or another 
are: Equisetum fluviatile, E. arvense, Sparganium 
minimum, Agrostis scabra, Calamagrostis cana- 
densis, C. stricta agg., Eleocharis palustris, Ca- 
rex aquatilis, C. lasiocarpa ssp. americana, C. 
oligosperma, C. rostrata, Juncus arcticus ssp. 
littoralis, J. brevicaudatus, J. filiformis, and Po- 
tentilla palustris. 

Occasional shrubs occur scattered as individuals 
or small groups and are derived from the floras of 
muskegs or stream banks: Juniperus communis. 
Salix lasiandra, S. pedicellaris, S. planifolia ssp. 
planifolia, S. pyrifolia, Betula glandulosa, Myrica 
gale, Alnus crispa, A. incana ssp. tenuifolia, Ribes 
triste, Ledum groenlandicum, Chamaedaphne ca- 
lyculata, Kalmia polifolia, Andromeda polifolia, 
Vaccinium uliginosum, and Viburnum edule. 

Plants in this vegetation that are not found in 
any other habitat are: TJorreyochloa pallida var. 
fernaldii, Carex buxbaumii, Eleocharis acicularis, 
E. quinqueflora, Scirpus cyperinus var. brachy- 
podus, §. microcarpus var. rubrotinctus, Juncus 
bufonius, Rumex mexicanus, Sagina nodosa ssp. 
borealis, Ramunculus hyperboreus, R. reptans, 
Rubus pubescens, Cicuta bulbifera, Artemisia 
borealis, and Solidago graminifolia var. major. 

Aquatic Vegetation. The Lake Athabasca sand 
dune region is relatively poor in aquatic vascular 
plants. The shallow waters off the shelving sandy 
beaches of Lake Athabasca seem to have no 
aquatics or very few of them. Bays protected from 
violent wave and ice action are essentially non- 
existent. We have collected 20 species thus far, 
from lagoons behind raised beaches along the 
main lake, from small inland ponds and lakes, and 
from a few sluggish streams. Twelve of them are 
strictly aquatic: Jsoetes muricata var. braunii, 
Sparganium angustifolium, S. fluctuans, Pota- 
mogeton alpinus var. tenuifolius, P. epihydrus 
var. ramosus, P. perfoliatus ssp. richardsonii, P. 
pusillus var. tenuissimus, Eleocharis palustris, 
Nuphar variegatum, Nymphaea tetragona, My- 
riophyllum spicatum ssp. exalbescens, M. verticel- 
latum var. pectinatum, Utricularia vulgaris ssp. 
macrorhiza, and Lobelia dortmanna. The remain- 
ing seven are also commonly found on wet sand 
Or a peaty substratum in the wet meadows or 


76 


shrub muskegs: Sparganium minimum, Potamo- 
geton gramineus, Polygonum amphibium var. 
stipulaceum, Callitriche verna, Hippuris vulgaris, 
Utricularia intermedia, and U. minor. 

Minor habitats. Three additional minor habi- 
tats should be mentioned here. Stony shores of 
Lake Athabasca have a small, though varied, flora 
drawn from the nearby sand beaches or from 
wetland habitats that subtend the shore in some 
places. They are somewhat more stable than the 
sand and have more shrub vegetation. The other 
two habitats are almost non-existent in the area 
with which we are dealing: sandstone ledges and 
crevices, and ruderal habitats. We have a few notes 
on ledges and crevices from east of Poplar Point 
where sandstone cliffs approach the south shore of 
the lake, but in the dune country only a few low 
ledges appear in the beds of streams. Occasional 
introduced ruderals have been collected around 
trapper’s cabins on the south shore of the lake, but 
we have made no studies of these sites. The 
opening of a road from the vicinity of Ennuyeuse 
Creek to Cluff Lake will no doubt bring in more 
ruderals. 


Acknowledgements 


Financial support for the 1935 field season on 
Lake Athabasca came from the Arnold Arbore- 
tum and the Milton Fund for Research, both of 
Harvard University. The National Museum of 
Canada was most generous in the loan of maps, 
aerial photographs, and field equipment. Field 
work in 1962 and 1963 was made possible by a 
grant from the National Research Council of 
Canada and the Institute for Northern Studies of 
the University of Saskatchewan. The 1972 trip to 
the William and MacFarlane River dunes was 
supported by the National Museum of Natural 
Sciences, and helicopter support was provided by 
Parks Canada through the Superintendent of 
Wood Buffalo National Park. The expedition in 
1975 was supported by the National Museum of 
Natural Sciences. 

We thank Parks Canada for the loan of aerial 
photographs made for them under a contract with 
Reinhard Hermesh. G.W. Argus would like to 
acknowledge particularly the cooperation and 
assistance of those who accompanied him on his 
trips to the dune region and to recognize the 
contribution that they have made to this study, 


Figure 52. Sedge meadow on sand. A precipitation ridge northeast of Little Gull Lake invading a meadow 
of Carex michauxiana, C. lasiocarpa, and C. oligosperma. 


including: Robert W. Nero, David J. White, 
Thomas Kovacs, George Ledingham, and F.H. 
Edmunds. 

We are greatly indebted to several individuals 
who have helped us during the preparation of this 
paper. They have been most generous not only 
with their time and their personal knowlege of our 
region and of reference material concerning it, but 
also with their understanding and encouragement. 
The interpretations of what they gave us are our 
own, and they are not responsible for any error we 
may have made in our use of it. 

We wish particularly to thank Reinhard Her- 
mesh and Derald Smith for giving us free use of 
the records of their studies in the Athabasca dune 
region, as these have made significant additions to 
our own. Dr. J.S. Rowe has given us steady 
encouragement, and arranged the loan of Her- 


ra 


mesh’s manuscript thesis from the Library of the 
University of Saskatchewan. Dr. William C. 
Noble supplied us not only with his own archaeo- 
logical data on the Indian cultures north and 
northeast of Great Slave Lake, but also gave us 
references to recent work in the Kazan, Dubawnt 
and Thelon basins. We are also appreciative of aid 
given us by Mr. E.A. Christiansen, Mr. W.C. 
Cody, Dr. Peter P. David, Dr. Margaret B. Davis, 
Mr. R. Green, Professor W.O. Kupsch, Dr. J. 
Ross Mackay, and Dr. J.V. Wright. 

Finally, we thank Mrs. G. Brown for typing the 
many drafts of the manuscript, John Argus and 
Lucy Raup for assisting with proofreading and 
Dr. J.H. Soper for critically reading the manu- 
script and offering many useful suggestions. 


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| 
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80 


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Appendix A. Sand Dune Fields and 
Parabolic Dunes south of Lake Athabasca 


The Maybelle River Sand Dunes 

In northeastern Alberta, just south of the 
western end of Lake Athabasca and about 55 km 
south southeast of Fort Chipewyan, lie the May- 
belle River sand dunes (Figure 53). They are 
positioned about 6 km north of Barber Lake and 3 
to 5 km west of Maybelle River. The dunes are 
located on a string of small lakes that are tributary 
to Maybelle River. These dunes, together with a 
smaller dune field west of the Richardson River 
(not visited by our parties), comprise the largest 
areas of active sand in northern Alberta. The 
Maybelle River dunes cover about 2800 ha and lie 
at an elevation of about 275 m. 

The dune field consists of two parabolic dunes 
that have coalesced and moved to their present 
position from at least as far west as the Richardson 
River (about 10 km). The dune field has a northern 
and a southwestern arm. Transverse dunes run 
parallel to the long axis of the north arm and 
perpendicular to the long axis of the southwest 
arm. The field exposes an undulating gravel 
pavement overlying sand. Within the dune field is 
a series of ponds and wet dune slacks draining into 
a small lake lying outside of the dune field. 

The precipitation ridges on the eastern and 
southern edges of the dune field have a steep lee 
slope which is invading forests and lakes. The 
windward side of the dune system consists of low 
sand hills that are being stabilized by forest. The 
border ridges, which are recognizable on the aerial 
photographs as light lines long after the area 
around them has been recolonized by plants, are 
low ridges gently sloping on both sides or often 
with a slightly steeper lee slope. 

The parabolic dune system in the Maybelle 
River area is somewhat intermediate in develop- 
ment between the simple parabolic dunes such as 
occur in the Archibald Lake area and the open 
dune systems, such as those west of the William 
River. It is possible that the Maybelle River dunes 
could develop into an open, self-sustaining dune 
system similar to the large dune fields in Saskat- 
chewan if they were exposed to strong north- 
easterly winds. This would reopen the western or 
windward edge of the parabolic dunes, thereby 
preventing the encroachment of the forest. In the 
past, however, the western edge of the dune system 
has not been kept open and forest has reinvaded 
the site as the parabolic dune migrated eastward. 


81 


It is probable that as the dune system is slowed by 
the Maybelle River and remains in that position 
for a long time it will become completely stabilized. 

The flora of the Maybelle River sand dunes is 
sufficiently different from that of the Saskatche- 
wan dunes to suggest that they have not been 
connected with the Saskatchewan dunes since 
their origin. The absence of all but one of the 
endemics known from the Saskatchewan dunes 
and the relatively recent origin of the parabolic 
dune complex support the assumption that the 
floras of the Alberta and Saskatchewan sand 
dunes have been isolated for a long time. 


The William River Sand Dunes 

The largest dune field lying south of Lake 
Athabasca is in the William River area between 
Ennuyeuse Creek and the William River (Figure 
54). The main dune field does not touch the lake 
shore but starts about 3-4 km south of the lake 
and extends inland about 15 km. The dune field is 
about 12 km wide, forming a roughly rectangular 
area oriented northwest-southeast. The area of the 
field is about 16 558 ha. The northern boundary of 
the field roughly parallels the 245 m contour, 
about 30.5 m above the present lake level, and the 
southernmost extent of the field is at about 275 m. 

From the air the dune system appears to be an 
extensive plain on which sand has been built up 
into a series of high dunes. The sand spills 
eastward into the William River (Figure 55) and 
westward into Ennuyeuse Creek. These drainages 
seem to act as barriers to expansion of the field by 
carrying sand north into Lake Athabasca. The 
northern and southern edges of the dune system 
consist of parabolic dunes some of which are 
separated from the main dune field. 

The major part of the western half of the dune 
system is a flat to rolling gravel pavement. The 
surface is covered with a gravel of relatively 
uniform size and boulders are uncommon. No 
distinct till deposits or source materials for the 
pavement veneer were found in the William River 
dune area to compare with that seen in the 
Thomson Bay dunes. Some gravel pavements, 
however, have coarse inclusions, including boul- 
ders, which may represent a glacial till deposit. 

A field of about 40 prominent oblique ridge 
dunes (Figure 54), trending in a northwest to 
southeast direction, forms a band through the 
center one-third of the dune field. Some of these 
dunes rise as much as 35 m above the gravel- 
covered surface, but in the southeastern part of the 


ss 
Sie or eo 
Aerts: 


pe Se 


Figure 53. Vertical aerial photograph of the parabolic sand dune complex west of Maybelle River. 
Transverse dunes are visible on the parabolic dune itself and border ridges can be seen trailing 
from the tips of the parabolicdune. (Alberta Dept. Energy and Natural Res. photograph 5803A.) 


82 


Figure 54. Vertical aerial photograph of the William River dune field. The William River traverses 


the upper right corner of the photograph and Ennuyeuse Creek traverses the lower corner. 
(National Air Photo Library photograph A-1561 1-9.) 


field the dunes are low and indistinct. The large 
dune fields around the William River are influ- 
enced by both westerly and northeasterly winds 
that have a long fetch across many kilometers of 
open lake and across wide treeless sand fields. The 
precipitation ridges of these fields are well devel- 
oped on all sides except on their northern and 
northwestern flanks. Under these circumstances, 
and over a long period of time, it might be 


83 


expected that most of the available sand would be 
blown into the precipitation ridges. This does not 
appear to be the case, however, for the largest 
dunes in the William River field occur not in the 
precipitation ridges but in the middle of the field. 
In general, the dunes of the large fields, including 
the precipitation ridges, decrease in height and in 


volume the farther they are from the shore of Lake 
Athabasca. 


Figure 55. Oblique aerial photograph of the William River looking north toward Lake Athabasca. The 
William River dune field appears on the left and a portion of the Thomson Bay field appears 


on the right. Floodplain forests of Picea glauca and Betula neoalaskana occur on islands 
in the foreground. 


84 


eS 


eo eT * 
ee ee ee 


Figure 56. Oblique aerial view of the Lake Athabasca shore looking westward from Thomson Bay across 
the delta of the William River to Sandy Bay. A parabolic dune (center) moving southeasterly is 
meeting and overriding a precipitation ridge moving northwesterly from the Thomson Bay 


dune field. 


The Thomson Bay Sand Dunes 

Extending east of the William River about 16 
km to Cantara Lake and from the shore of Lake 
Athabasca 8 km south to Little Gull Lake are the 
Thomson Bay sand dunes (Figure 56). This dune 
field covers about 9680 ha and lies between 
elevations of 214 m, at the lake shore, and 305 m 
inland. The eastern edge of the field grades into a 
complex of parabolic dunes which occur scattered, 
as isolated patches of sand, to the Wolverine Point 
dunes. 

This large dune field, as well as the William 
River dune field, is best understood from the 
vantage point of Lake Athabasca for the lake has 
played a major role in its development. Along a 
transect from Lake Athabasca to Little Gull Lake 
the open dune area can be seen to rise in indistinct 
steps toward the south. The landscape near the 
shore consists of low transverse dunes or rolling 
dune topography usually covered by Betula or 
Salix. Farther inland the vegetation becomes 
Sparser, consisting mainly of grasses and Tanace- 
tum, and then all plants are absent near the center 
of the dune field. A little over half way into the 
dune field, gravel pavement appears and continues 


85 


to a point near the southern edge of the field. In 
general, the dune area itself is featureless and 
monotonous consisting of low undulating dunes 
and gravel pavement ridges and plains. Near the 
southern edge of the dune field, the landscape is 
more complex with the appearance of wet dune 
slacks, precipitation ridges invading forests and 
muskegs, and with the development of parabolic 
dunes. The southern edge of the field parallels a 
drainage system including Little Gull Lake and a 
number of other smaller lakes. South of these 
lakes the landscape is a flat plain gradually rising 
southward. It is covered with gravel and a promi- 
nent elongated ridge which runs east-west just 
south of Little Gull Lake (Figure 6). This ridge is 
made up of an unsorted mixture of coarse stones 
and boulders in a sandy matrix. The plain on 
which the ridge is lying also consists of unsorted 
sand and gravel. There are no stabilized sand 
dunes in the area or other features that would 
suggest that this area was ever a part of an open 
dune field. 

The importance of opposing winds in maintain- 
ing large open dune fields can be seen at the 
northwestern edge of the Thomson Bay dunes. 


PO 


Figure 57. Vertical aerial photograph of Archibald Lake. A series of parabolic dunes meet the lake on its 
westerly and northerly shores. The tracks left by the dunes resemble an “embroidery” pattern. 
(Sask. Dept. of Tourism and Renewable Res. photograph H 14434-81.) 


Here a parabolic dune, driven by northwesterly 
winds, is moving southeastward (Figure 56). Along 
its eastern edge the parabolic dune is invading and 
burying forest and along its western edge forest is 
reinvading the site. 

The Thomson Bay dune field, itself, under the 
influence of opposing winds, is moving both 
northwestward as well as to the east and southeast 
and precipitation ridges occur along both its 
northeastern and northwestern edges. Where the 
parabolic dune and the dune field come into 
contact, the higher precipitation ridge of the 
parabolic dune is overriding the precipitation 
ridge of the dune field. It is probable that, as these 
two sand fronts merge the precipitation ridge will 
deflate slightly and will permit the easterly winds 
to reopen the western edge of the parabolic dune, 
thereby incorporating it into the larger dune 
system. 


86 


The Archibald Lake Sand Dunes 

Located between the Thomson Bay dunes and 
those at Wolverine Point are the Archibald Lake 
dunes. The lake itself is located 13 km south of 
Turnor Point on the Lake Athabasca shore and 32 
km east of William River. On the north shore of 
Archibald Lake there are six open parabolic sand 
dunes that have migrated from the west. The paths 
of the dunes are marked by stabilized dunes and 
border ridges (Figure 57). 

On the north side of Archibald Lake there are 
alternating bands of low, stabilized sand dunes 
with intervening wet depressions. The active para- 
bolic dunes in the area are moving across a 
stabilized, rolling sand plain and in places they are 
invading the lake. Four dunes are coalescing along 
the north shore of the lake and where they meet the 
lake a sand spit has been built. At the lake edge the 
old land surface is being eroded by the wind 


| 


Figure 58. Oblique aerial photograph of the easternmost of the three dune fields at Wolverine Point. 
(National Air Photo Library photograph A 2595-60.) 


leaving perched remnants of forest. The largest of 
the active parabolic dunes is about 0.8 km long 
and 0.5 km wide and covers about 65 ha, but most 
of the dunes in the area are only half that size. 
These parabolic dunes are essentially large blow- 
outs with active dune fronts invading forest and 
wetland and having windward edges that are 
becoming stabilized by forest. The flora of these 
small, active sand dunes is much like that of the 
larger dune complexes and they include some, but 
not all, of the endemic taxa known from the major 
dune areas. 


The Wolverine Point Sand Dunes 

Three small dune fields lie on either side of 
Wolverine Point (Figure 1). The point is low, 
blunt, about 3 km wide at the base, and projects 
about | km into the lake. It is about 26 km west of 
the mouth of MacFarlane River. The Archibald 
River follows an eastward-bulging curve and then 
subtends Wolverine Point and enters Lake 
Athabasca at the western base of the point. There 


87 


are low sandstone ledges in the bed of the streama 
short distance above its mouth and some gravel 
in bars at the shore of the lake. 

The two larger sand dune areas come out to the 
lake shore in shallow bays on either side of the 
point and a third smaller (probably parabolic) 
dune of about 40 ha is located on the point itself. 
The easternmost of the dune areas 1s about 1.5 km 
wide (N-S) and about 2 km long (E-W). It covers 
about 335 ha and lies between elevations of 214 
and 245 m. The western dune area borders the west 
bank of the Archibald River for about 2 km above 
its mouth and then swings southward another 0.5 
km making a roughly triangular mass about 1.5 
km wide and reaching south from the lake about 3 
km. It covers about 510 ha and lies between 
elevations of 214 and 275 m. 

From the air (Figure 58), it can be seen that the 
eastern, southeastern, and parts of the southern 
margins of the Wolverine Point dunes are sharply 
defined against the dark gray tones of the forested 
surfaces. In contrast, the western and northwestern 


Figure 59. Vertical aerial photographs of the MacFarlane River dune field. Yakow Lake appears on the 
upper edge of the photograph and what appears to be an old precipitation ridge that has 
become stabilized by vegetation is indicated by arrows. (Sask. Dept. of Tourism and 


Renewable Res. photograph YC 7624-50.) 


margins are “feathered out,” showing a gradual 
transition from the sand to the forest, often with 
small areas of forest surrounded by open sand. At 
the eastern margin of the dunes a precipitation 
ridge, inundating a forest of Pinus banksiana, 
produces the sharply defined margins seen in the 
aerial photograph. 

The western and northwestern margins are 
characterized by expanses of level or very gently 
rolling surfaces with trees widely spaced as indivi- 
duals or small groves. The sand is partly stabilized 


88 


by fruticose lichens, a few mosses, and trailing 
shrubs. West of these margins, the trees gradually 
become more frequent and the sand is more 
completely stabilized. Finally, a continuous forest 
with small sand blowouts appears. 

It is probable that the amount of sand involved 
in the Wolverine Point dunes is not as great as 
would appear from surface observations. The 
gradually rising surface back of most of the lake 
shores is marked by high sand or gravel ridges that 
were formed on the receding shore of glacial Lake 


McConnell and are counterparts of those that 
characterize the present shore. They and the 
smaller ridges and lagoon areas between them 
have supplied most of the sand for the dunes. The 
active dunes have completely effaced some of the 
ridges but others have maintained their identity as 
ridges or terraces among the dunes more or less 
parallel to the shore of the lake. These ridges may 
be composed of sand or gravel, depending on their 
position with respect to outcrops of sandstone or 
glacial till at the shores on which they were 
formed. Gravel pavements are common among 
the dunes where blowing sand has exposed them. 
On these areas ventifacts are often abundant. 


The MacFarlane River Sand Dunes 

A large dune field'located near the eastern end 
of Lake Athabasca is bisected by the MacFarlane 
River. The main dune field, consisting of two more 
or less separated areas, extends about 10 km west 
of the river and a smaller dune area extends about 
3 km east of the river (Figure 59). The western 
dune area touches Lake Athabasca at a point just 
west of Yakow Lake, its northern edge curves 
southeastward touching the south shore of Yakow 
Lake, and then swings eastward to the MacFarlane 
River meeting it ‘at a point about 3 km from its 
mouth. The farthest inland extent of the main 
dune field is about 6 km south of Lake Athabasca 
and the smaller, eastern dune area lies about 5 km 
south of the lake. The western dune field covers 
about 4570 ha and the eastern dune area about 355 
ha. The dunes lie between elevations of 214 m at 
the Lake Athabasca shore to 305 m at its inland 
limit. 

The westernmost patch of open dunes almost 
reaches Lake Athabasca at its northern tip and it 


89 


has well developed precipitation.ridges on its 
eastern and southern flanks. The southern part of 
the western area is an extensive gravel pavement 
with scattered, shallow sand dunes moving across 
it. It is separated from the main dune field by a 
strip of vegetation about 5 km long and 1.5 km 
wide. There are signs of former extensive parabol- 
ic dune activity in this area but now it is almost 
completely covered by jack pine forest. 

Along the northern edge of the main dune field 
there is a series of large parabolic dunes which 
have partially coalesced, leaving behind them 
parallel bands of forest running at right angles to 
the dune margin. The southern portion of the 
main dune field is a large area of sand plain and 
gravel pavement leading to precipitation ridges on 
its southern and eastern sides. In the central part 
of the main dunes there is a complex of intersect- 
ing sand dunes meeting each other at about right 
angles. The volume of sand in the MacFarlane 
River dunes seems to be less than that in the 
William River and Thomson Bay dunes and the 
water table is seldom exposed in the dune slacks. 

The smaller dune area east of the river can be 
seen from the western dunes as sand cliffs along 
the shore (Figure 60). It appears to be spreading 
both to the east and to the west as indicated by the 
location of precipitation ridges. 


Unvisited Saskatchewan Sand Dunes 

Between Thomson Bay and Royal Lake is a 
series of parabolic dunes and small dune fields that 
cover about 1820 ha. These dunes were not visited 
by our parties. From aerial photographs they 
appear to be similar to the dune fields in the 
Wolverine Point area or the smaller parabolic 
dunes north of Archibald Lake. 


Figure 60. View of the MacFarlane River and a dune field east of the river. Floodplain white spruce-birch 
forests appear in the center. 


90 


Appendix B. Checklist of the Flora of the 
South Shore of Lake Athabasca. 


The checklist of the flora is based primarily on 
voucher specimens that we have examined, but 
some sight records and literature records are 
included as indicated. Major collections of vou- 
cher specimens of the vascular flora are housed in 
ALTA, CAN, DAO, GH, and SASK; the bryo- 
phytes in CANM, SASK, and UAC; and the 
lichens in CANL, COLO, SASK, UAC, and US 
(herbarium acronyms follow Holmgren & Keu- 
ken, 1974). Most of the collections were identified 
by the authors, but the following botanists aided 
in the identification or verification of certain 
groups: I.M. Brodo, H. Crum, A. Cronquist, M. 
Hale, V. Harms, R.. Ireland, I.M. Lamb, J.W. 
Thomson, W. Weber, and P.Y. Wong. 


Vascular Plants 


LYCOPODIACEAE 

Lycopodium annotinum L. 

. clavatum L. 

. complanatum L. 

. dendroideum Michx. 

. Inundatum L. 

. selago L. 

. sitchense Rupr. 
SELAGINELLACEAE 
Selaginella rupestris (L.) Spring 

ISOETACEAE 
Tsoetes muricata var. braunii (Engelm.) Reed 

EQUISETACEAE 
Equisetum arvense L. 

E. fluviatile L. 
E. palustre L. 
E. sylvaticum L. 

POLY PODIACEAE 
Gymnocarpium dryopteris (L.) Newm. 
Polypodium vulgare ssp. virginianum (L.) Hult. 

CUPRESSACEAE 
Juniperus communis L. 

PINACEAE 
Larix laricina (Du Roi) Koch 
Picea glauca var. albertiana (S. Brown) Sarg. 
P. mariana (Mill.) BSP 
Pinus banksiana Lamb. 

P. banksiana X contorta Loud. 

TYPHACEAE 
Typha latifolia L. 

SPARGANIACEAE 


CS CAS Paes 


Sparganium angustifolium Michx. 

S. fluctuans (Morong) B.L. Robinson 

S. minimum (Hartm.) Fries 
NAIADACEAE 

Potamogeton alpinus ssp. tenuifolius(Raf.) Hult. 

P. alpinus var. subellipticus (Fern.) Ogden 

Potamogeton epihydrus var. ramosus (Peck) 

House 

P. gramineus L. 

P. obtusifolius Mert. & Koch 

P. perfoliatus ssp. richardsonii (Benn.) Hult. 

P. pusillus var. tenuissimus Mert. & Koch 
JUNCAGINACEAE 

Triglochin maritimum L. 


SCHEUCHZERIACEAE 
Scheuchzeria palustris ssp. americana (Fern.) 
Hult. 
ALISMATACEAE 
Sagittaria cuneata Sheldon 
POACEAE 


Agropyron smithii Rydb. 

A. trachycaulum (Link) Malte 

Agrostis scabra Willd. 

Bromus pumpellianus Scribn. 

Calamagrostis canadensis (Michx.) Beauv. 

C. lapponica (Wahlenb.) Hartm. 

C. purpurascens R. Br. 

C. stricta (Timm) Koeler agg. (incl. C. stricta ssp. 
stricta and ssp. neglecta (Gray) C.W. 
Greene) 

Deschampsia mackenzieana Raup 

Dichanthelium acuminatum (Swartz) Gould & 
Clark (Panicum subvillosum Ashe) 

Elymus mollis Trin. 

Festuca rubra L. ssp. rubra 

F. rubra ssp. richardsonii (Hook.) Hult. 

Festuca saximontana Rydb. 

Glyceria borealis (Nash) Batchelder 

G. pulchella (Nash) Schum. 

Hordeum jubatum L. 

Koeleria macrantha (Ledeb.) Schultes (K. cristata 
(U.) Pers.) 

Oryzopsis pungens (Torr.) Hitche. 

Phragmites australis (Cav.) Steudel (P. communis 
Trin.) 

Poa glauca Vahl 

P. lanata Scribn. & Merrill 

P. pratensis L. 

Torreyochloa pallida var. fernaldii(Hitchc.) Dore 

Trisetum spicatum ssp. molle (Michx.) Hult. 

CYPERACEAE 

Carex abdita Bickn. 


. aenea Fern. 
. aquatilis Wahlenb. 
brunnescens ssp. sphaerostachya (Tuckerm.) 
Kalela 
. buxbaumii Wahlenb. 
. canescens L. 
. chordorrhiza L. f. 
. deflexa Hornem. 
. diandra Schrank 
. lasiocarpa ssp. americana (Fern.) Hult. 
Carex leptalea Wahlenb. 
C. limosa. L. 
C. livida (Wahlenb.) Willd. 
C. magellanica ssp. irrigua (Wahlenb.) Hult. (C. 
paupercula Michx.) 
. maritima Gunner 
. michauxiana Boeckl. 
oligosperma Michx. 
. pauciflora Lightf. 
pseudocyperus L. 
. rostrata With. 
. rufina Drej. (unconfirmed report) 
siccata Dewey 
stenophylla ssp. eleocharis (Bailey) Hult. 
(Unconfirmed report) 
. tenuiflora Wahlenb. 
. tonsa (Fern.) Bickn. (C. umbellata var. tonsa 
Fern.) 
C. trisperma Dewey 
Eleocharis acicularis (L.) R. & S. 
E. palustris (L.) R. &S. 
E. quinqueflora (Hartm.) Schwarz (E. pauciflora 
Link.) 
Eriophorum branchyantherum Trautv. & Meyer 
E. chamissonis Meyer 
E. gracile Koch 
E. polystachion L. (E. angustifolium Honck.) 
E. tenellum Nutt. 
E. vaginatum ssp. spissum (Fern.) Hult. 
Rhynchospora alba (L.) Vahl 
KR. fusca (L.) Ait. f. 
Scirpus caespitosus L. 
S. cyperinus var. brachypodus (Fern.) Gilly (S. 
atrocinctus Fern.) 
S. hudsonianus (Michx.) Fern. 
S. microcarpus var. rubrotinctus (Fern.) M. E. 
Jones 
S. subterminalis Torr. 
ARACEAE 
Calla palustris L. 
JUNCACEAE 
Juncus alpinus Vill. 


Ga. 


Preteen ss Gy 


Cae Oy Cy ey 


Gre) 


92 


J. arcticus ssp. littoralis (Engelm.) Hult. (J. balti- 
cus Var. littoralis Engelm.) 

J. brevicaudatus (Engelm.) Fern. 

J. bufonius L. (incl. var. halophilus Buch. & Fern.) 

J. filiformis L. 

J. stygius ssp. americanus (Buch.) Hult. 

J. vaseyi Engelm. 
LILIACEAE 

Maianthemum canadense var. interius Fern. 

Smilacina trifolia (L.) Desf. 
ORCHIDACEAE 

Arethusa bulbosa L. 

Calypso bulbosa (L.) Oakes 

Cypripedium acaule Ait. 

JGoodyera repens (L.) R. Br. 

Spiranthes romanzoffiana Cham. 
SALICACEAE 

Populus balsamifera L. 

P. tremuloides Michx. 

Salix arbusculoides Anderss. 

. athabascensis Raup 

. bebbiana Sarg. 

. brachycarpa Nutt. var. psammophila Raup 

. brachycarpa X pyrifolia 

. brachycarpa X turnorii 

discolor Muhl. 

lasiandra Benth. 

lutea Nutt. 

pedicellaris Pursh 

pellita Anderss. 

planifolia Pursh ssp. planifolia 

planifolia ssp. tyrrellii (Raup) Argus 

. pyrifolia Anderss. 

scouleriana Hook. 

. Silicicola Raup 

. turnorii Raup 

MYRICACEAE 

Myrica gale L. 
BETULACEAE 

Alnus crispa (Ait.) Pursh 

A. incana ssp. tenuifolia (Nutt.) Breitung 

Betula glandulifera (Regel) Butler 

B. glandulosa Michx. 

B. neoalaskana Sarg. 

B. occidentalis Hook. 

B. papyrifera Marsh. 

B. X sargentii Dugle (glandulifera X glandulosa) 

B. X utahensis Britton (occidentalis X papyrifera) 

B. X winteri Dugle (neoalaskana X papyrifera) 
SANTALACEAE 

Comandra umbellata ssp. pallida (DC.) Piehl 

Geocaulon lividum (Richards.) Fern. 
POLYGONACEAE 


ANANRHRARHRHUHDHDNAHHY 


Polygonum achoreum Blake 
P. amphibium var. stipulaceum (Coleman) Fern. 
P. lapathifolium var. salicifolium Sibth. 
Rumex mexicanus Meisn. 
R. occidentalis Wats. 
CHENOPODIACEAE 
Chenopodium album L. 
Corispermum hyssopifolium L. 
CARYOPHYLLACEAE 
Sagina nodosa ssp. borealis Crow 
Silene acaulis L. f. acaulis 
S. acaulis f. athabascensis Argus 
Stellaria arenicola Raup 
S. crassifolia Ehrh. 
S. longifolia Muhl. 
S. longipes Goldie 
NYMPHAEACEAE 
Nuphar variegatum Engelm. 
Nymphaea tetragona Georgi 
RANUNCULACEAE 
Caltha palustris L. 
Coptis trifolia (L.) Salisb. (C. groenlandica (Oeder) 
Ranunculus aquatilis var. capillaceus (Thuill.) 
DC. 
R. gmelini DC. 
R. hyperboreus Rottb. 
R. lapponicus L. 
R. reptans L. (R. flammula var. filiformis (Michx.) 
Hook.) 
CRUCIFERAE 
Arabis arenicola (Richards.) Gelert 
A. lyrata ssp. kamchatica (Fisch.) Hult. 
Capsella bursa-pastoris (L.) Medic. 
SARRACENIACEAE 
Sarracenia purpurea L. 
DROSERACEAE 
Drosera anglica Huds. 
D, linearis Goldie 
D. rotundifolia L. 
SAXIFRAGACEAE 
Saxifraga tricuspidata Rottb. 
Parnassia palustris ssp. neogaea (Fern.) Hult. 
GROSSULARIACEAE 
Ribes hudsonianum Richards. 
R. triste Pall. 
ROSACEAE 
Amelanchier alnifolia Nutt. 
Fragaria virginiana ssp. glauca (S. Wats.) Staudt 
Potentilla norvegica L. 
P. palustris (L.) Scop. 
P. tridentata Soland. 
Prunus pensylvanica L. f. 
Rosa acicularis Lindl. 


Rubus chamaemorus L. 
R. idaeus ssp. sachalinensis (Lev\.) Focke 
R. pubescens Raf. 
Sorbus scopulina Greene 
FABACEAE 
Lathyrus ochroleucus Hook. 
Vicia americana Willd. 
CALLITRICHACEAE 
Callitriche verna L. 
EMPETRACEAE 
Empetrum nigrum L. 
HYPERICACEAE 
Hypericum majus (Gray) Britton 
CISTACEAE 
Hudsonia tomentosa Nutt. 
Lechea intermedia var. depauperata Hodgdon 
ONAGRACEAE 
Epilobium angustifolium L. 
E. ciliatum ssp. glandulosum (Lehm.) Hoch & 
Raven 
E. leptophyllum Raf. 
E. palustre L. 
HALORAGIDACEAE 
Myriophyllum spicatum ssp. exalbescens (Fern.) 
Hult. 
M. verticillatum var. pectinatum Wallr. 
HIPPURIDACEAE 
Hippuris vulgaris L. 
ARALIACEAE 
Aralia nudicaulis L. 
APIACEAE 
Cicuta bulbifera L. 
C. mackenzieana Raup 
CORNACEAE 
Cornus canadensis L. 
PYROLACEAE 
Chimaphila umbellata ssp. occidentalis (Rydb.) 
Hult. 
Monotropa uniflora L. 
Orthilia secunda (L.) House 
Pyrola asarifolia Michx. 
P. chlorantha Sw. 
P. elliptica Nutt. 
P. minor L. 
ERICACEAE 
Andromeda polifolia L. 
Arctostaphylos uva-ursi var. coactilis Fern. & 
Macbr. 
Chamaedaphne calyculata (L.) Moench 
Kalmia polifolia Wang. 
Ledum groenlandicum Oeder 
L. palustre var. decumbens Ait. 


Oxycoccus quadripetalus Gilib. 
Vaccinium myrtilloides Michx. 
V. uliginosum L. 
V. vitis-idaea ssp. minus (Lodd.) Hult. 
PRIMULACEAE 

Lysimachia thrysiflora L. 

Trientalis borealis ssp. latifolia (Hook.) Hult. 
PLUMBAGINACEAE 

Armeria maritima ssp. interior (Raup) Pors. 
GENTIANACEAE 

Menyanthes trifoliata L. 
APOCYNACEAE 

Apocynum androsaemifolium L. 
LAMIACEAE 

Lycopus uniflorus Michx. 
SCROPHULARIACEAE 

Melampyrum lineare Destr. 

Pedicularis parviflora Smith 

Rhinanthus crista-galli L. 

Veronica americana Benth. 

LENTIBULARIACEAE 

Utricularia cornuta Michx. 

U. intermedia Hayne 

U. minor L. 

U. vulgaris ssp. macrorhiza (LeConte) Clausen 

RUBIACEAE 
Galium trifidum L. 
CAPRIFOLIACEAE 
Linnaea borealis ssp. americana (Forbes) Hult. 
Viburnum edule (Michx.) Raf. 
CAM PANULACEAE 
Campanula rotundifolia L. 
LOBELIACEAE 
Lobelia dortmanna L. 
ASTERACEAE 

Achillea lanulosa Nutt. ssp. lanulosa 

A. lanulosa ssp. megacephala (Raup) Argus 

Antennaria nitida Greene | 

Artemisia borealis Pall. 

Aster puniceus L. 

Erigeron acris var. asteroides (Andrz.) DC. 

Hieracium umbellatum L. 

Petasites palmatus (Ait.) Gray 

Senecio congestus var. palustris (L.) Fern. 

Solidago decumbens var. oreophila(Rydb.) Fern. 

S. graminifolia var. major (Michx.) Fern. 

S. nemoralis var. longipetiolata (Mack. & Bush) 
Palmer & Steyerm. (S. nemoralis var. de- 
cemflora (DC.) Fern.) 

Tanacetum huronense var. bifarium Fern. 

T. huronense var. floccosum Raup 


Bryophytes 


Andreaea rupestris Hedw. 

Aulacomnium palustre (Hedw.) Schwaegr. 

Bryum  pseudotriquetrum (Hedw.) Gaertn., 
Meyer & Scherb. 

Calliergon stramineum (Brid.) Kindb. 

Ceratodon purpureus (Hedw.) Brid. 

Dicranum polysetum Sw. (D. rugosum (Funck) 
Hoffm.) 

Drepanocladus exannulatus (B.S.G.) Warnst. 

D. uncinatus (Hedw.) Warnst. 

Helodium blandowii (Web. & Mohr.) Warnst. 

Hypnum lindbergii Mitt. 

Orthodicranum montanum (Hedw.) Loeske (Di- 
cranum montanum Hedw.) 

Plagiomnium ciliare (C. Mill.) Kop. (Mnium 
affine var. ciliare C. Mill.) 

P. ellipticum (Brid.) Kop. (Mnium affine var. 
rugicum (Laur.) B.S.G.) 

Pleurozium schreberi (Brid.) Mitt. 

Pogonatum urnigerum (Hedw.) P. Beauv. 

Pohlia drummondii (C. Mill.) Andr. 

P. nutans (Hedw.) Lindb. 

Polytrichum commune Hedw. var. commune 

P. commune var. perigoniale (Michx.) Hampe 

P. juniperinum Hedw. 

P. piliferum Hedw. 

Pseudoleskella tectorum (Brid.) Broth. (Leskea 
tectorum (Funck) Lindb.) 

Ptilium crista-castrensis (Hedw.) De Not. 

Rhacomitrium canescens (Hedw.) Brid. 

Sphagnum centrale C. Jens. 

S. compactum DC. 

S. majus (Russ.) C. Jens. (S. dusenii C. Jens.) 

S. fuscum (Schimp.) Klinggr. 

S. magellanicum Brid. 

S. recurvum P. Beauv. var. recurvum 

S. recurvum var. brevifolium (Lindb.) Warnst. (S. 
recurvum Var. mucronatum(Russ.) Warnst.) 

S. squarrosum Crome 

S. teres (Schimp.) Angstr. 

Sphagnum warnstorfii Russ. 


Liverworts 


Marchantia polymorpha L. 
Ptilidium ciliare (L.) Hampe 
P. pulcherrimum (G. Web.) Hampe 


Lichens 


Acarospora smaragdula (Wahlenb.) Mass. 


Aspicilia cinerea (L.) Korb. (Lecanora cinerea(L.) 
Somm.) 

Bryoria chalybeiformis (L.) Brodo & D. Hawksw. 

B. furcellata (Fr.) Brodo & D. Hawksw. 

B. fuscescens (Gyeln.) Brodo & D. Hawksw. 

B. lanestris (Ach.) Brodo & D. Hawksw. 

B. nadvornikiana (Gyeln.) Brodo & D. Hawksw. 

B. simplicior (Vain.) Brodo & D. Hawksw. 

Buellia lacteoidea B. de Lesd. 

Cetraria cucullata (Bell.) Ach. 

ericetorum ssp. reticulata (Ras.) Karnef. 

halei W. Culb. & C. Culb. 

hepatizon (Ach.) Vain. 

islandica (L.) Ach. ssp. islandica 

laevigata Rass. 

nigricans (Retz.) Nyl. 

C. nivalis (L.) Ach.’ 

C. pinastri (Scop.) S. Gray 

C. subalpina Imsh. 

Cetrelia olivetorum (Nyl.) W. Culb. & C. Culb. 

Chaenothecopsis sp. 

Chrysothrix chlorina (Ach.) Laundon, Ined. (Le- 
praria chlorina (Ach.) Sm.) 

Cladina arbuscula (Wallr.) Rabenh. (Cladonia 
sylvatica (L.) Hoffm.) 

C. mitis (Sandst.) Hale & W. Culb. (Cladonia 
mitis Sandsi.) 

C. rangiferina (L.) Nyl. (Cladonia rangiferina (L.) 
Wigg.) 

C. stellaris (Opiz) Pouz. & Vézda (sight record) 

Cladonia amaurocraea (Flérke) Schaer. 

. bellidiflora (Ach.) Schaer. 

. cenotea (Ach.) Schaer. 

. chlorophaea (Somm.) Spreng. 

. coccifera (L.) Willd. 

. cornuta (L.) Hoffm. 

. crispata (Ach.) Flot. 

. cristatella Tuck. 

. deformis (L.) Hoffm. 

. gracilis ssp. turbinata (Ach.) Ahti 

C. phyllophora Hoffm. 

C. sulphurina (Michx.) Fr. 

C. uncialis (L.) Wigg. 

Coelocaulon aculeatum (Schreb.) Gyeln. (Corni- 
cularia aculeata (Schreb.) Ach.) 

Dimelaena oreina (Ach.) Norm. 

Evernia mesomorpha Ny). 

Huilia crustulata (Ach.) Hertel 

Hypocenomyce scalaris (Ach.) Choisy (Lecidea 
scalaris Ach.) 

Hypogymnia physodes (L.) Nyl. (Parmelia phy- 
sodes (L.) Ach.) 

Icmadophila ericetorum (L.) Zahlbr. 


# 
G. 
c. 
a 
C. 
Cs 


io ip Gk a ak > Ya > mG Gp 


95 


Lasallia pensylvanica (Hoffm.) Llano 

Lecanora badia (Pers.) Ach. 

L. chrysoleuca (Sm.) Ach. (L. rubina (Vill.) Ach.) 

L. melanophthalma Ram. 

L. polytropa (Ehrh.) Rabenh. 

Lecidea auriculata Th. Fr. 

L. epiiodiza Nyl. (L. somphotera (Vain.) Oliv.) 

L. granulosa (Ehrh.) Ach. 

Lecidella elaeochroma (Ach.) Haszl. 

Lepraria sp. 

Parmelia disjuncta Erichs. 

P. exasperatula Ny). 

P. flaventior Stirt. 

. saxatilis (L.) Ach. 

. soredica Nyl. (P. ulophyllodes (Vain.) Sav.) 

. sorediosa Almb. 

. stygia (L.) Ach. 

. sulcata Tayl. 

Parmeliopsis ambigua (Wulf.) Nyl. 

P. hyperopta (Ach.) Arn. 

Peltigera aphthosa (L.) Willd. 

P. canina (L.) Willd. 

P. malacea (Ach.) Funck 

P. rufescens (Weis) Humb. 

P. spuria (Ach.) DC. 

Physcia adscendens (Th. Fr.) Oliv. 

P. aipolia (Humb.) Fiirnr. 

Ramalina american Hale 

R. dilacerata (Hoffm.) Vain. ( Fistulariella minus- 
cula (Nyl.) Bowler & Rundel) 

R. intermedia (Nyl.) Nyl. 

R. obtusata (Arn.) Bitt. 

Rhizocarpon cinereovirens (Mill. Arg.) Vain. 

. geographicum (L.) DC. 

. grande (Flot.) Arn. 

. hochstetteri (K6rb.) Vain. 

. norvegicum Ras. 

. reductum Th. Fr. 

. riparium Ras. 

Rinodina sp. 

Stereocaulon alpinum Laur. var. alpinum 

S. alpinum var. gracilentum Magn. 

S. botryosum Ach. 

S. condensatum Hoffm. 

S. glareosum (Sav.) Magn. 

S. grande (Flot.) Arn. 

S. paschale (L.) Hoffm. 

S. rivulorum Magn. 

S. tomentosum Fr. 

Umbilicaria hyperborea (Ach.) Hoffm. 

U. muhlenbergii (Ach.) Tuck. 

Usnea cavernosa Tuck. 

U. filipendula Stirt. 


a ~~ Ps 


DA AARAA 


U. hirta (L.) Wigg. X. conspersa (Ach.) Hale (P. conspersa Ach.) 


U. sorediifera group X. incurva (Pers.) Hale (P. incurva (Pers.) Fr.) 

U. subfloridana Stirt. X. separata (Th. Fr.) Hale (P. separata Th. Fr.) 

Xanthoparmelia centrifuga (L.) Hale (Parmelia X. taractica (Kremp.) Hale (P. taractica Kremp.) 
centrifuga (L.) Ach.) Xanthoria polycarpa (Ehrh.) Oliv. 


96