GLACIAL LAKES WHICH MARKED THE DECLINE OF THE LAST ICE AGE
[Illustration:
FIG. 346.—The Illinois River where it passes through the outer moraine
at Peoria, Illinois, showing the flood plain of the ancient stream as
an elevated terrace into which the modern stream has cut its gorge
(after Goldthwait).]
=Interference of glaciers with drainage.=—Every advance and every
retreat of a continental glacier has been marked by a complex series
of episodes in the history of every river whose territory it has
invaded. Whenever the valley was entered from the direction of its
divide, the effect of the advancing ice front has generally been to
swell the waters of the river into floods to which the present streams
bear little resemblance (Fig. 346). Because of the excessive melting,
this has been even more true of the ice retreat, but here _when the ice
front retired up the valley_ toward the divide. A sufficiently striking
example is furnished by the Wabash, Kaskaskia, Illinois, and other
streams to the southward of the divide which surrounds the basin of the
Great Lakes (Fig. 347).
[Illustration:
FIG. 347.—Broadly terraced valleys outside the divide of the St.
Lawrence basin, which remain to mark the floods that issued from the
latest continental glacier during its retreat (after Leverett).]
Wherever the relief was small there occurred in the immediate vicinity
of the ice front a temporary diversion of the streams by the parallel
moraines, so that the currents tended to parallel the ice front. This
temporary diversion known as “border drainage” was brought to a close
when the partially impounded waters had, by cutting their way through
the moraines, established more permanent valleys (Fig. 348).
=Temporary lakes due to ice blocking.=—Whenever, on the contrary, the
advancing ice front entered a valley from the direction of its mouth,
or a _retreating ice front retired down the valley_, quite different
results followed, since the waters were now impounded by the ice front
serving as a dam. Though the histories of such blocking of rivers
are often quite complex, the principles which underlie them are in
reality simple enough. Of the lakes formed during advancing hemicycles
of glaciation, and of all save the latest receding hemicycle, no
satisfactory records are preserved, for the reason that the lake
beaches and the lake deposits were later disturbed and buried by the
overriding ice sheets. We have, however, every reason to suppose that
the histories of each of these hemicycles were in every way as complex
and interesting as that of the one which we are permitted to study.
[Illustration:
FIG. 348.—Border drainage about the retreating ice front south of Lake
Erie. The stippled areas are the morainal ridges and the hachured bands
the valleys of border drainage (after Leverett).]
As an introduction to the study of the ice-blocked lakes of North
America, and to set forth as clearly as may be the fundamental
principles upon which such lakes are dependent, we shall consider
in some detail the late glacial history of certain of the Scottish
glens, since their area is so small and the relief so strong that
relationships are more easily seen; it is, so to speak, a pocket
edition of the history of the more extended glacial lakes.
[Illustration:
FIG. 349.—The “parallel roads” of Glen Roy in the southern highlands
of Scotland (after Jamieson).]
=The “parallel roads” of the Scottish glens.=—In a number of
neighboring glens within the southern highlands of Scotland there are
found faint terraces upon the glen walls which under the name of the
“parallel roads” (Fig. 349) have offered a vexed problem to scientists.
Of the many scientists who long attempted to explain them, though in
vain, was Charles Darwin, the father of modern evolution. He offered it
as his view that the “roads” were beaches formed at a time when the sea
entered the glens and stood at these levels. When, however, Jamieson’s
studies had discovered their true history, Darwin, with a frankness
characteristic of some of the greatest scientists, admitted how far
astray he had been in his reasoning. Let us, then, first examine the
facts, and later their interpretation. The map of Fig. 350 will suffice
to set forth with sufficient clearness the course of the several
“roads.” These “roads” are found in a number of glens tributary to
Loch Lochy, and of the three neighboring valleys, Glen Roy has three,
Glen Glaster two, and Glen Spean one “road.” The facts of greatest
significance in arriving at their interpretation relate to their
elevations with reference to the passes at the valley heads, their
abrupt terminations down-valleyward, and the morainic accumulations
which are found where they terminate. The single “road” of Glen Spean
is found at an elevation of 898 feet, a height which corresponds to
that of the pass or col at the head of its valley and to the lowest of
the “roads” in both Glens Glaster and Roy. Similarly the upper of the
two “roads” in Glen Glaster is at the height of the pass at its head
(1075 feet) and corresponds in elevation to the middle one of the three
“roads” in Glen Roy. Lastly, the highest of the “roads” in Glen Roy is
found at an elevation of 1151 feet, the height of the col at the head
of the Glen. In the neighboring Glen Gloy is a still higher “road”
corresponding likewise in elevation to that of the pass through which
it connects with Glen Roy.
[Illustration:
FIG. 350.—Map of Glen Roy and neighboring valleys of the Scottish
highlands with the so-called “roads” entered in heavy lines. Glens Roy,
Glaster, and Spean have three “roads”, two “roads”, and one “road”,
respectively (after Jamieson).]
To come now to the explanation of the “roads”, it may be said at
the outset that they are, as Darwin supposed, beach terraces cut by
waves, not as he believed of the ocean, but of lakes which once filled
portions of the glens when glaciers proceeding from Ben Nevis to the
southwestward were blocking their lower portions. The several episodes
of this lake history will be clear from a study of the three successive
idealistic diagrams in Fig. 351.
[Illustration: FIG. 351.—Three successive diagrams to set forth in
order the late glacial lake history of the Scottish glens.]
To derive the principles underlying this history, it is at once seen
that _all changes are initiated by the retirement of the ice front to
such a point that it unblocks for the waters of a lake an outlet that
is lower than the one in service at the time_. This is the principle
which explains nearly all episodes of glacial lake history. Thus, when
the ice front had retired so as to open direct connections between Glen
Roy and Glen Glaster, the col at the head of Glen Roy was abandoned as
an outlet, and the waters fell to the level fixed for Glen Glaster.
A still further retirement at last opened direct connection between
Glen Glaster and Glen Spean, so that the lake common to Glens Glaster
and Roy fell to the level of the col which was the outlet of the Spean
valley at the time. This stage continued until the ice front had
retired so far that the waters drained naturally down the river Spean
to Loch Lochy and thence to the ocean.
[Illustration: FIG. 352.—Harvesting time on the fertile floor of the
glacial Lake Agassiz (after Howell).]
Only in their far grander scale and in the lesser relief of the
land over which they formed, do the complex histories of the great
ice-blocked lakes of North America differ from these little valley
lakes whose beaches may be visited and the relationships worked out,
thanks to Jamieson, in a single day’s strolling.
[Illustration: FIG. 353.—Map of Lake Agassiz (after Upham).]
=The glacial Lake Agassiz.=—The grandest of the temporary lakes
referable to blocking by the continental glaciers of the ice age must
be looked for in the largest valleys that lay within the territory
invaded and _which normally drain toward the retiring ice front_.
In North America these rivers are the Red River of the North in
Minnesota, the Dakotas, and Manitoba; and the St. Lawrence River
system. To the ice dam which lay across the Red River valley we owe the
fertility of that vast plain of lake deposits where is to-day the most
intensive wheat farming of the northwest (Fig. 352). Lakes Winnipeg,
Winnipegoosis, and Manitoba, and the Lake of the Woods, are all that
now remain of this greatest of the glacial lakes, which in honor of
the distinguished founder of the glacial theory has been called Lake
Agassiz (Fig. 353). With their natural outlet blocked by the ice in
northern Manitoba and Keewatin, the waters of the Red were swollen by
melting from the retiring glacier and spread over a vast area before
finding a southern outlet along the course of the present Lake Traverse
and the valley of the Minnesota River. Along this route there flowed a
mighty flood which carved out a broad valley many times too large for
the Minnesota, its present occupant, and this giant prehistoric river
has been called the Warren River (Fig. 354).
[Illustration:
FIG. 354.—Map of the southern end of the Lake Agassiz basin, showing
the position of some of the beaches and the outlet through the former
Warren River (after Upham).]
[Illustration: FIG. 355.—Narrows of the Warren River below Big Stone
Lake, where it passed between jaws of hard granite and gneiss (after
Upham).]
[Illustration:
FIG. 356.—Map of the valley of the Warren River in the vicinity of
Minneapolis, with the young valley of the Mississippi entering it at
Fort Snelling (after Sardeson).]
It is interesting to follow this ancient waterway and to discover
that, like our normal, present-day streams, it was held up in narrows
wherever outcroppings of harder rock had constricted its channel
(Fig. 355). The upper end of the Warren River valley is now occupied
by the long and relatively narrow Lakes Traverse and Big Stone, each
the result of blocking by delta deposits where a tributary stream
has emerged into the valley, but this gigantic channel continues
down to and beyond Minneapolis, occupied as far as Fort Snelling
by the Minnesota River—a mere pygmy compared to its predecessor.
To the earnest student of glacial geology there can be few sights
more impressive than are obtained by standing at Fort Snelling, just
above the confluence of the Minnesota and the Mississippi rivers, and
surveying first the steep and narrow valley of the Mississippi above
the junction,—a stream fitted to its valley for the simple reason that
it has carved it,—and then gazing up and down that broad valley in
which the great Warren River once flowed majestically to the sea, now
the bed of the Minnesota above the Fort and of the Mississippi below it
(Fig. 356).
[Illustration:
FIG. 357.—Portion of the Herman quadrangle of Minnesota, showing the
position of the Herman beach on the shore of the former Lake Agassiz.
The lake basin is to the left, and the pitted morainal deposits appear
to the right (U. S. G. S.).]
Just as the “parallel roads” of Glen Roy, roads in name only, are the
beaches of earlier glacial lake stages, so in Lake Agassiz we have
parallel beaches of the barrier type which are often roads in fact as
well as in name, and which mark the stages of successive lakes within
this vast basin. The Herman beach, corresponding to the highest level
of the lake, is thus a sharp topographic boundary between lake deposits
and morainal accumulations, and is further itself a well-marked
topographic feature composed of wave-washed and hence well-drained
materials (Fig. 357). Farmers of the district have been quick to
realize that these level and slightly elevated ridges lack the clay
which would render them muddy in the wet seasons, and are thus ideally
adapted for roads. They have in many sections been thus used over long
stretches and are known as the “ridge roads.”
=Episodes of the glacial lake history within the St. Lawrence
valley.=—Within this great drainage basin it has apparently been
possible to read the records of each stage in the latest lake
history—complex as this has been. We have only to recall the lake
stages cited from the Scottish glens and remember that each new stage
was begun in a retirement of the glacier front which unblocked an
outlet of lower level than the last. This sequence might, however,
have been varied by a temporary readvance of the ice, as indeed once
occurred in the Huron-Erie lobe of the great North American glacier.
[Illustration:
FIG. 358.—The continental glacier of North America in an early stage
of its recession, when it covered the entire St. Lawrence drainage
basin. The dashed line is the approximate position of the divide (based
on a map by Goldthwait).]
[Illustration:
FIG. 359.—Outline map of the early Lake Maumee, with the bordering
moraine and the water-laid moraine remaining on the site of the former
ice cliff.]
=The crescentic lakes of the earlier stages.=—So long as the glacier
covered the entire drainage basin of the St. Lawrence River system, all
water was freely drained away by streams which flowed _away from_ the
ice front (Fig. 358). So soon, however, as at any point the front had
retired behind the divide, impounding of the waters must locally have
occurred. Lakes of this type are to-day to be seen in Greenland and
in the southern Andes; and though upon a diminutive scale, some idea
of their aspect may be obtained from the appearance of the Märjelen
Lake of Switzerland, here blocked by a mountain glacier (Fig. 446, p.
411). Within all areas of small relief, such as the prairie country
surrounding the present Laurentian lakes, the earlier and smaller
stages of such ice-blocked lakes are generally crescentic in outline.
This is because a moraine in most cases forms the land margin of the
lake, and because the ice cliff upon the opposite border, although
somewhat straightened, as a consequence of wave-cutting and iceberg
formation, still retains the convex outlines characteristic of ice
lobes (Fig. 359).
[Illustration: FIG. 360.—Map to show the first stages of the
ice-dammed lakes within the St. Lawrence basin (after Leverett and
Taylor).]
Within each of the Great Lake basins a crescentic lake early appeared
at that end of the depression which was first uncovered by the
glacier: Lake Duluth in the Superior basin, Lake Chicago in the
Michigan basin, and Lake Maumee in the Huron-Erie basin (Fig. 360).
We may now, with profit, trace the successive episodes of the glacial
lake history, considering for the earlier stages those changes which
occurred within the Huron-Erie basin, since, these are in essential
respects like those of the Michigan and Superior basins, although
worked out in greater detail. Lake Chicago must, however, be brought
into consideration, since in all save the earliest and the later
stages, the waters from the Huron-Erie depression were discharged
through the Grand River into this lake and thence by the so-called
“Chicago outlet” into the Mississippi (plate 20 A).
=The early Lake Maumee.=—The area, outline, and outlet of this lake
are indicated upon Fig. 360. Its ancient beaches have been traced, as
well as the water-laid moraine beneath its former ice cliff; and no
observant traveler who should take his way down the ancient outlet
from Fort Wayne, Indiana, past the town of Huntington, could fail to
be impressed by its size, suggesting as it does the great volume of
water which must once have flowed along it. Now a channel a mile or
more in width, its bed for the twenty-five miles between Fort Wayne
and Huntington may be seen from the tracks of the Wabash Railway as a
series of swamps merely, while at Huntington the Wabash river enters by
a young V-shaped valley at the side, much as the Mississippi emerges
into the old channel of the Warren River at Fort Snelling, Minnesota
(see p. 327).
The Huron River of southern Michigan, which now discharges into Lake
Erie, then found its lower course blocked by the glacier and was thus
compelled to find a southerly directed channel now easily followed to
the northern horn of the crescent of Lake Maumee.
=The later Lake Maumee.=—When the ice lobe had retired its front
sufficiently, an outlet lower than that at Fort Wayne was uncovered
past the city of Imlay, Michigan, into the Grand River, and thence
through Lake Chicago and its outlet into the Mississippi. This old
outlet south of Chicago follows the course of the present Drainage
Canal and the line of the Chicago & Alton Railway. The traveler
journeying southward by train from Chicago has thus the opportunity of
observing first the beaches of the former lake, and then the several
channels which were joined in the main outlet at the station of Sag
(plate 20 A).
[Illustration: FIG. 361.—Outline map of the later Lake Maumee and of
its “Imlay outlet” to Lake Chicago (after Leverett).]
In this stage of our history Lake Maumee pushed a shrunk arm up past
the site of Ypsilanti in Michigan (Fig. 361), the well-marked beach
being found on Summit Street opposite the State Normal College. The
Huron River, which in the first lake stage had followed the valley now
occupied by the Raisin River southward into Indiana, now discharged
directly into a bay upon this arm of Lake Maumee, and so formed a delta
at Ann Arbor.
[Illustration: FIG. 362.—Outline map of Lakes Whittlesey and Saginaw
(after Leverett).]
[Illustration:
FIG. 363.—Map of the glacial Lake Warren, the last of the lakes in the
Huron-Erie basin, which discharged through the “Grand River outlet”
into the Mississippi (after Leverett).]
=Lakes Arkona and Whittlesey.=—The ice front in the Huron-Erie basin
now retired so far that the impounded waters, instead of following
the more direct “Imlay outlet” to the Grand, passed at a lower level
completely around “the thumb” of Michigan into the Saginaw basin.
Meanwhile a crescent-shaped lake had developed in that basin, so that
now the waters of the Maumee basin were joined to those in the Saginaw
basin as a common lake, just as the lowering of the waters in Glen Roy
caused a union with those of Glen Glaster in the example cited for
illustration. Our records of this third North American lake stage,
referred to as Lake Arkona, are however most imperfect, for the reason
that it was followed by a readvance of the ice front which closed the
passage around “the thumb” and raised the level of the waters until
an outlet was found past the town of Ubly at a lower level than the
“Imlay outlet.” When the waters of a lake are thus rising, strong beach
formations result, and those of this stage, which is known as the Lake
Whittlesey stage, are much the strongest that are found within the
Huron-Erie basin. Traced for some three hundred miles entirely around
the southern and western margins of Lake Erie, this beach is for much
of the distance the famous “ridge road” (Fig. 362).
=Lake Warren.=—As the ice advance which had produced Lake Whittlesey
came to an end, the normal recession was resumed and a lake once more
formed as a body common to the Saginaw and Erie basins. This lake,
known as Lake Warren, extended a shrunk arm far eastward along the ice
front into western New York, though it was still blocked from entering
the great Mohawk valley (Fig. 363).
[Illustration: FIG. 364.—Map of the Glacial Lake Algonquin (after
Leverett).]
=Lakes Iroquois and Algonquin.=—It must be evident that toward the
close of the Lake Warren stage a profound change was imminent—a
transfer of the glacial waters from their course to the Mississippi
and the Gulf to the trench which crosses New York State and enters the
Atlantic. So soon as the ice front had retired sufficiently to lay
bare the bed of the Mohawk, an outlet was found by this route and its
continuation down the Hudson valley to the sea. The Lake Ontario basin
now became occupied by a considerably larger water body known as Lake
Iroquois, and the three upper lakes, then joined as Lake Algonquin,
discharged their combined waters into Lake Iroquois at first through a
great channel now strongly marked across Ontario in the course of the
Trent River and Lake Simcoe, the so-called “Trent outlet.” At this time
a smaller Lake Erie probably occupied the basin of that lake, and later
the Trent outlet was abandoned for the Port Huron outlet (Fig. 364).
[Illustration: FIG. 365.—Outline map of the Nipissing Great Lakes with
their outlet past North Bay into the Champlain Sea.]
=The Nipissing Great Lakes.=—We have now followed the ice front
step by step in its retreat across the valley of the St. Lawrence
system. The successive unblocking of outlets offers but one further
possibility—the opening of the French River-Nipissing Lake-Ottawa
River, or “North Bay outlet.” Though not so to-day, the bed of this
ancient channel was then much lower than that of the “Mohawk outlet”,
and so soon as the glacier had in its retreat uncovered this northern
channel, the waters of the upper lakes discharged through it past the
site of Ottawa and into an arm of the sea which then occupied the lower
St. Lawrence valley and has been called the Champlain Gulf or Sea
(Fig. 365). The level of the waters was lowered and the area of the
lakes correspondingly reduced.
The reader who has had no opportunity to observe these ancient channels
which carried the swollen waters of the former glacier lakes, will find
it interesting to consider that every one of them has been fixed upon
by engineers for improvement as artificial waterways. Thus we have the
Illinois Drainage Canal and projected ship canal along the “Chicago
outlet”, the projected Mississippi-Lake Erie Canal along the “Fort
Wayne outlet”, the Grand River canal project to connect Lake Michigan
and Saginaw Bay along the course of the “Grand River outlet”, the
Trent Canal along the “Trent outlet”, the Erie Canal along the “Mohawk
outlet”, and, lastly, the proposed Georgian Bay ship canal to the ocean
along the “North Bay” or “Nipissing outlet.”
=Summary of lake stages.=—We have omitted in this summary of late lake
history in the Laurentian basin all the less important lake stages,
including some of a transitional nature which were represented by
beaches and outlets easily traced to-day. This is because it is an
outline only which it seems best to present, and the episodes of this
abridged history may be tabulated as follows:
EPISODES OF GLACIAL LAKE HISTORY
MISSISSIPPI DRAINAGE
Lake Maumee (early), Fort Wayne outlet.
Lake Maumee (late), Imlay City outlet.
Lake Arkona, “thumb” outlet.
Lake Whittlesey (with readvance of glacier), Ubly outlet.
Lake Warren, “thumb” outlet.
ATLANTIC DRAINAGE
Lakes Iroquois and Algonquin (early), Trent and Mohawk outlets.
Lakes Iroquois and Algonquin (late), Port Huron and Mohawk outlets.
Nipissing Great Lakes, North Bay outlet.
=Permanent changes of drainage affected by the glacier.=—While the
lake history which we have sketched is made up of episodes which
endured only while the ice front lay between certain stations upon its
retreat, there were none the less brought about the profoundest of
permanent modifications in the drainage of the region. It is possible
to restore upon maps in part only the preglacial drainage of the north
central states, but we know at least that it was as different as may be
from that which we find to-day. The Missouri and the Ohio take their
courses to-day along the margin of the glaciated area as an inheritance
from the border drainage of the ice age. Within the glaciated regions
rivers have in many cases been compelled by morainal obstructions to
enter upon new courses, or even to travel in the opposite direction
along their former channels. In districts of considerable relief these
diversions have sometimes caused the streams to plunge over the walls
of deep valleys, and it may truthfully be said that we owe much of our
most beautiful scenery in part to the carving and molding of glaciers,
but especially to the cascades and waterfalls directly due to their
interference with drainage.
[Illustration:
FIG. 366.—Probable preglacial drainage of the upper Ohio region (after
Chamberlin and Leverett).]
Many diversions or reversals of former drainage lines, through the
influence of the continental glacier, are at once suggested by
the abnormal stream courses, which appear upon our maps, and the
correctness of these suggestions may often be confirmed by very simple
observations made upon the ground. The map of Fig. 366 shows how
different was the preglacial drainage of the upper Ohio region from
that of to-day.
An interesting additional example is furnished by the Still River
which in Connecticut is tributary to the Farmington, and is no less
remarkable for its abnormal northerly course and sluggish current
perpetuated in its name, than for the way in which it is joined to the
Farmington system (Fig. 367 _A_). A careful study of the district has
shown that the Still River was once a part of the Naugatuck and flowed
southward toward Long Island Sound like other rivers of the district
(Fig. 367 _B_). It possessed, however, an advantage in a narrow belt
of softer rock along its course, and because of this advantage it
captured a portion of one of the tributaries to the Farmington (Fig.
367 _C_). The continental glacier later covered the region, and on its
retreat laid down morainal obstructions directly across this river and
also at the head of the severed arm of the Farmington tributary (Fig.
367 _D_). The now impounded waters found their lowest outlet near Sandy
Brook, and in waterfalls and cascades the now reversed river falls one
hundred feet to the bed of that stream. With the aid of the excellent
topographic maps which are now supplied by a generous government at a
merely nominal price, such bits of recent history may be read at many
places within the glaciated region.
[Illustration:
FIG. 367.—Diagrams to illustrate the episodes in the recent history
of the Still River tributary to the Farmington in Connecticut. _A_,
present drainage; _B_, early stage; _C_, after capture of a tributary
to the Farmington; _D_, after blocking by morainal obstructions of the
ice age.]
=Glacial Lake Ojibway in the Hudson Bay drainage basin.=—When by
passing over the “height of land” in northern Ontario the greatly
reduced continental glacier had vacated the basin of St. Lawrence
drainage, it was in a position to impound those waters which normally
drained to Hudson Bay. The lake which then came into existence has been
called Lake Ojibway and was the latest of the entire series. Though of
but recent discovery in a country till lately a trackless wilderness,
its extension seems to have been that of the clay beds suited for
farming. The beaches and outlets remain to be mapped when the country
has been made more easily accessible.
READING REFERENCES FOR CHAPTER XXIII
Parallel roads of Glen Roy:—
CHARLES DARWIN. Observations on the Parallel Roads of Glen Roy and of
Other Parts of Lochaber in Scotland, with an attempt to prove that
they are of Marine Origin, Phil. Trans., vol. 8, 1839, pp. 39-82.
LOUIS AGASSIZ. Geological Sketches, Boston, 1876, vol. 2, pp. 32-76.
T. T. JAMIESON. On the Parallel Roads of Glen Roy and their Place in
the History of the Glacial Period, Quart. Jour. Geol. Soc. Lond., vol.
19, 1863, pp. 235-259.
Glacial Lake Agassiz:—
WARREN UPHAM. The Glacial Lake Agassiz. Mon. 25, U. S. Geol. Surv.,
pp. 658, pls. 38.
F. W. SARDESON. Beginning and Recession of St. Anthony’s Falls, Bull.
Geol. Soc. Am., vol. 19, 1908, pp. 29-36.
Glacial lakes in the St. Lawrence valley:—
CHAMBERLIN AND SALISBURY. Geology, vol. 3, pp. 394-405.
FRANK LEVERETT. Outline of the History of the Great Lakes
(Presidential Address), 12th Rept. Mich. Acad. Sci., 1910, pp. 19-42.
The Pleistocene Features and Deposits of the Chicago Area. Chicago,
1897, pp. 86, pls. 8 (Chicago Outlet).
H. L. FAIRCHILD. Glacial Lakes in Western New York, Bull. Geol. Soc.
Am., vol. 6, 1895, pp. 353-374, pls. 18-23; Glacial Waters in Central
New York. Bull. 127, N. Y. State Mus., 1909, pp. 66, pls. 42, and maps
in cover.
Early lakes in the Erie basin:—
FRANK LEVERETT. On the Correlation of Moraines with Raised Beaches of
Lake Erie, Am. Jour. Sci. (3), vol. 43, 1892, pp. 281-301.
F. B. TAYLOR. The Great Ice Dams of Lakes Maumee, Whittlesey, and
Warren, Am. Geol., vol. 24, 1899, pp. 6-38, pls. 2-3; Relation of Lake
Whittlesey to the Arkona Beaches, 7th Rept. Mich. Acad. Sci., 1905,
pp. 30-36.
FRANK LEVERETT. The Ann Arbor Folio, Folio No. 155, U. S. Geol. Surv.,
1908, pp. 10-12.