The Problem of 

. the Cochrane in

Late Pleistocene 

* Chronology

¥

GEOLOGICAL SURVEY BULLETIN 1021-J

A CONTRIBUTION TO GENERAL GEOLOGY

4 -

THE PROBLEM OF THE COCHRANE IN LATE 

PLEISTOCENE CHRONOLOGY

By THOR N. V. KAKLSTROM

.ABSTRACT

The precise position of the Cochrane readvances in the Pleistocene continental 

chronology has long been uncertain. Four radiocarbon samples bearing on the 

age of the Cochrane events were recently dated by the U. S. Geological Survey. 

Two samples (W-241 and W-242), collected from organic beds underlying surface drift in the Cochrane area, Ontario, are more than 38,000 years old. Two 

samples (W-136 and W-176), collected from forest beds near the base and middle 

of a 4- to 6-foot-thick peat section overlying glacial lake sediments deposited after 

ice had retreated north of Cochrane, have ages, consistent with stratigraphic 

position, of 6,380±350 and 5,800±300 years. These results indicate that the 

Cochrane area may have been under a continuous ice cover from before 36,000 

until some time before 4500 B. C.; this conforms with the radiocarbon dates of 

the intervening substage events of the Wisconsin glaciation. The radiocarbon 

results indicate that the Cochrane preceded rather than followed the Altithermal climatic period and suggest that the Cochrane be considered a Wisconsin 

event of substage rank.

Presented geoclimatic data seemingly give a consistent record of a glaciation 

and eustatic sea level low between 7000 and 4500 B. C., which appears to correlate with the Cochrane as a post-Mankato and pre-Altithermal event. A direct 

relation between glacial and atmospheric humidity changes is revealed by comparing the glacioeustatic history of late Pleistocene and Recent time with independently dated drier intervals recorded from Western United States, Canada, 

and Europe. The combined geoclimatic record supports the concept of a fundamental ' climatic cycle with a base periodicity of about 500-600 (550) years, 

strong recurrences every 1,000-1,200 (1,100) years, and major recurrences every 

3,000-4,000 (3,400) years.

Many radiocarbon dates independently substantiate the European Fennoscandian varve date of 8,800-8,100 B. C., the correlation of the Mankato with the 

Fennoscandian substage of the European chronology, and the correlation of the 

Cochrane with a post-Fennoscandian climatic event. Therefore, the correlation 

of the Cochrane with the Fennoscandian in the North American varve'chronology 

appears untenable.

303
304 CONTRIBUTIONS TO GENERAL GEOLOGY

INTRODUCTION

 t 

The youngest recognized readvances of the ice margins during

retreat of the Wisconsin ice sheet from. North America were first 

described by Ernst Antevs (1925) from the type locality near Coch- ^ 

rane, northern Ontario, Canada. These readvances, also referred to 

as oscillations or halts, constitute the Cochrane age of the continental 

chronology and were subsequently treated in a series of papers dealing 4. 

with the development and refinement of a varve chronology covering 

the retreatal events of the last ice age (Antevs, 1928, 1931, 1953). 

The Cochrane occupies a signally important position in the development of the late Pleistocene absolute chronology of North America 

because Antevs' meticulously and laboriously derived varve sequence, 

upon which this chonology has been based, terminates with it. Dating 

of the Cochrane in calendar years, therefore, has been requisite to 

the absolute dating by varves of the pre-Cochrane events of the Wisconsin glaciation and thus, indirectly, to the dating of important _/ 

archeological finds of early man in North America, as well as fundamental to the elaboration of climatic history since the maximum advance of the last ice age. <

The age of Cochrane is still highly controversial. Because of its 

importance to the late Pleistocene and Eecent chronology, a suite of 

four samples of peat and wood collected from the Cochrane area 

were recently dated at the radiocarbon laboratory of the United 

^tates Geological Survey, Washington, D. C. (Kubin and Suess, 

1955,1956). The purpose of this paper, is to discuss the implications i

of these four analyses in relation to other critical data and previous 

attempts to date' the Cochrane. The conclusion is reached that the 

Cochrane marks an important period of halts, some time between 

7000 and 4500 B. C., during final retreat of the Wisconsin ice sheet 

from the St. Lawrence region of Canada. ^

EVIDENCE FOB THE COCHKANE

/*

As summarized in a recent paper (Antevs, 1953), the Cochrane 

is described as three separate readvances of the ice margin in the vicinity of Cochrane, Canada. These readvances were preceded by a 

generally rapid retreat of the ice margins from the position of the

Mankato and Yalders moraines in the United States and were folio-wed by a rapid retreat and final disappearance of the continental ,-*.

ice sheet from the Hudson Bay region. The halts marking these readvances are recorded by an outwash apron or sandr (Icelandic) near

Nellie Lake, 23 miles south of Cochrane; by remnants of an end 4 

moraine present in the Suskequa and Frederick House Rivers and at 

Cochrane in the vicinity of latitude 50° N.; and by the Turgeon Bend 

moraine, which lies about 50 miles north of Cochrane (fig. 55). On ^
PROBLEM OF THE COCHRANE IN LATE PLEISTOCENE CHRONOLOGY 305

40'

80° Modified from sketch maps by Antevs.1953; 

Flint, 1953, and Horberg. 1955

FIGURE 55 Sketch map of Cochrane, Ontario, and adjacent regions.

the basis of varve stratigraphy, Ernst Antevs postulates ice* readvances of about 70 miles to Nellie Lake, 3 miles to the moraine at 

Cochrane, and an advance of an unknown distance (or a halt) to the 

Turgeon Bend moraine. According to his varve chronology, these 

three readvances took place in an interval of less than 1,000 years. 

Although R. F. Flint (1953, p. 9i4) considers the question of actual 

ice readvance within the Cochrane areas still unsettled, the moraine 

and sandr deposits would appear to demonstrate a related series of 

definite interruptions in the recession of the continental ice margins and, therefore, a significant .climatic event in post-Mankato time.
306' CONTRIBUTIONS TO GENERAL GEOLOGY

.HISTORICAL DEVELOPMENT OF THE COCHRANE PROBLEM

|

Pleistocene geologists generally accept the reality of the Cochrane 

oscillations as a significant climatic event, but the age of the oscillations has long been in dispute. In his early papers Ernst Antevs 

(1928, 1931) tentatively assumes that post-Cochrane time is the correlative of the Postglacial time of the northern European chronology 

and thereby assigns an age of about 7000 B. C. to the Cochrane. By 

counting back in time on the basis of varve counts and estimates for 

the gaps in his varve sequence, he derives an age of about 23,000 B. C. 

for tne St. Johnsbury moraine of Vermont and an age of 34,500 to 

35,000 B. C. for the New York moraines on Long Island (the Ronkohkoma and Harbor Hill moraines). He suggests that the St. Johnsbury moraine is the correlative of the Mankato substage of the 

Wisconsin stage and of the Pomeranian substage in Europe and that 

the New York moraines are the correlative of the lowan substage of 

the Wisconsin stage and of the European Warthe glaciation.

Kirk Bryan and L. L. Ray (1940) present a critical review of Mr. 

Antevs' (1928, 1931) chronologies, emphasizing the inherent uncertainties represented by the many gaps in the North American varve 

sequence and by the suggested continental and transatlantic correlation of moraines. In a reestimate of available data, admittedly by 

rather arbitrary means, they derive an age of 8000 B. C.± 1,000 years 

for the Cochrane by assuming that either post-Cochrane time is the 

equivalent of the European Postglacial (6800 B. C. to present) or 

that the Cochrane is the equivalent of the European Fennoscandian 

glacial substage dated about 8500 B, C. They follow Antevs in correlating the St. Johnsbury moraine with the Mankato and the Pomeranian but disagree with him in that they consider the Harbor Hill 

moraine a separate substage from the Ronkonkoma moraine. They 

suggest the following chronology for Wisconsin events and correlate 

with the European glacial sequence as follows: Wl (Wisconsin 1) 

lowan (Warthe), 65,000 B. C.; W2-Tazewell and Gary (Brandenburg), 35,000 B. C.; W3-Mankato (Pomeranian), 25,000 B. C.; 

W4r-? (Scanian halt), 11,500 B. C.; Cochrane? (Fennoscandian),

8500 B. C.; and post-Cochrane (Postglacial), beginning about 

6800 B. C. They emphasize that the ages suggested are but first

approximations which, because of the magnitude of the inherent

errors involved in their calculations^ must be considered indicators

of relative age rather than true figures. They note that the attempted

correlation Of the North American with the northern European sequence is somewhat unsatisfactory in that the Scanian halt in Europe

has no apparent American counterpart, It is evident that the ages of 

the events, including the Cochrane, are derived solely by transatlantic 

correlations, whereas the ages of the earlier Wisconsin events are esti-
PROBLEM OF THE COCHRANE IN LATE PLEISTOCENE CHRONOLOGY 307

mates based on combining Ernest Antevs' varve data with what Kirk 

Bryan and L. L. Ray consider the most probable correlations of the 

morainal sequence of the east coast with that of the Midwest and with 

European type sections.

In 1949, successful results obtained by dating archeological organic 

material of known age by the newly developed radiocarbon method 

were announced (Arnold and Libby, 1949), and a program was immediately inaugurated to further develop and test the method as a 

tool to be used in the solution of geologic and archeological chronological problems. By 1951 a sufficient number of geologic samples of 

unknown age had been dated to permit a cautious estimate of the 

validity of the radiocarbon method in supplying accurate dates (Flint, 

1951). Two general results emerged: the radiocarbon dates in general 

agreed with the stratigraphic positions of samples, implying at least 

proper relative ages; and the dates obtained for geologic events were 

generally more recent than had been believed by many geologists. 

The most significant result bearing directly on the age of the Cochrane 

was the dating of thepre-Mankato interstadial (Two Creeks interval) 

at about 9500 B. C. This age is in apparent agreement with the varve 

date of just slightly older than 8800 B. C. applied to the pre-Fennoscandian interstadial (Allerod horizon) of northern Europe and implies that the Fennoscandian is the equivalent of the Mankato and 

not the Cochrane.

Ernst Antevs (1953) reassesses his varve chronology in the light of 

the new radiocarbon data and argues, on the basis of similar position 

and sequence of moraines relative to ice sources, that the Fennoscandian must be the correlative of the Cochrane and not the Mankato, as 

implied by the radiocarbon age of the Two Creeks formation. By 

equating the 3 Cochrane readvances with the 3 Finnish Salpauselka 

moraines (varve dated from 8800 to 8100 B. C.), he derives a new base 

line of 9300 B. C. for his pre-Cochrane varve sequence and dates the 

St. Johnsbury moraine (Mankato) at about 17,200-17,000 B. C., the 

New Britain moraine (Gary) at about 21,900-21,600 B. C., and the 

Harbor Hill moraine (Tazewell) at some time before 25,000 B. C. 

After summarizing the varve record for the Mankato to Cochrane 

interval (5,225 counted years (varves) and 2,625 estimated years), 

Antevs concludes that his estimates for the duration of this interval 

can be too low, but hardly too high. Thus the 9000 B. C. radiocarbon 

date for the Mankato must be too young by about a factor of 2. In 

an evaluation of radiocarbon dates, which do hot agree with his varvebased chronology, he suggests that the main causes for radiocarbon 

error are contamination by younger organic material and old carbonates, and wet decomposition, which determines a chemical exchange affecting the original radioactive composition of the organic

388997 56 2
308

material. Whereas it is now generally recognized that occasional 

spurious radiocarbon dates may result from contamination of samples 

by both younger and older organic material, research on isotope fractionation (Craig, 1953) reveals no physiochemical basis for the contention that" organic material preserved in a wet environment suffers a 

fractionation not experienced : by material preserved in a dry 

environment.

> A series of radiocarbon analyses run on samples collected from the 

pre-Fennoscandian Allerod pollen zone in Denmark gave results in 

agreement with the Fennoscandian varve date (Anderson, Levi, and 

Tauber, 1953). Eeruns of samples from the American Two Creeks 

and the European Allerod zones by the more sensitive and accurate 

acetylene counting method developed by Suess substantiate the general 

accuracy of the ages derived by the original solid-carbon counting 

method of Libby (Suess, 1954). It would therefore appear that the 

radiocarbon ages of the Two Creeks interval and the Allerod period 

and the essential contemporaniety of the related Mankato and Fennoscandian events are rather firmly established. The agreement between the radiocarbon and varve dates for the Fennoscandian is highly 

significant. Not only does this agreement appear to substantiate the 

essential accuracy of the Scandinavian varve chronology over the 

past 11,000 years, but it implies that properly analyzed radiocarbon 

samples provide results that may be accurate in a near-absolute as 

well as a relative sense, at least up to 11,000 years and presumably 

beyond.

In 1953 a new interpretation was introduced, adding to the Cochrane problem. E. S. Deevey (1953), following a suggestion by R. F. 

Flint (1953), placed the Cochrane as a post-Thermal Maximum event 

and a correlative of the "little ice age" of Matthes. According to 

Matthes (1949), the "little ice age" began around 2000 B, C,; and a

"lesser ice age," around the end of the 16th century. The term "Thermal Maximum" was used by Flint and Deevey (1951) to designate the 

postglacial period of maximum warmth (essentially the Atlantic 

period of the Scandinavian climatic chronology), which has been 

referred to also as the Climatic Optimum, Altithermal, or xerothermic 

period (Deevey, 1953, p. 277-279). 

As the Thermal Maximum is dated by Deevey from 5000 to 3000

B. C., this requires a post-3000 B. C. age for the Cochrane. A. C. 

Trowbridge (1954) disagrees. In a review of the literature dealing

with Pleistocene chronology and sea-level changes, Trowbridge places 

the Cochrane as a pre-Thermal Maximum event and arrives at a

Cochrane age of about 13,000 5500 B. C. by using the admittedly dubious method of averaging out previously published estimates. Trowbridge discards the possibility of the Cochrane as a post-Thermal Maxi-
PROBLEM OF THE COCHRANE IN LATE PLEISTOCENE CHRONOLOGY 309

mum event on the basis that an ice sheet large enough to reach as farsouth as Cochrane could hardly have melted away at the same time 

that the less extensive glaciers of the "little ice age" advanced. R. L. 

Nelson (1954), in a study of the glacial geology of the Frying Pan 

River drainage in Colorado, derives, from a quasi-quantitative evaluation of relative difference in weathering and erosional characteristics 

of glacial deposits, an age of about 3500 B. C. for a glaciation (Chapman Gulch) which he correlates with the Cochrane. Although the 

general validity and accuracy of the dating method and of his correlation of the Colorado events with the midcontinental sequence may 

be questioned, Nelson's attempt is noteworthy as a well-considered approach to the difficult problem of making relative geologic data .yield 

results in absolute years.

By 1955 a sufficient number of radiocarbon results were available 

from both the United States and Alaska to permit dating of glacial 

events throughout Wisconsin and post-Wisconsin time, to assess better 

the radiocarbon results relative to geologic interpretation, and to 

establish more firmly their validity (Flint and Rubin, 1955; Horberg, 

1955; Karlstrom, 1955). Two major conclusions were derived independently by the authors of these three papers: (1) glacial events of 

Wisconsin age are compressed into a somewhat surprisingly short period of time and relate to a major glaciation that began before 23,000 

B. C., reached a maximum about 18,000-16,000 B. C., and was in oscillating Retreat up to and after 9000 B. C.; and (2) the logical and consistent agreement of the great number of radiocarbon dates with geological interpretation indicates that the radiocarbon method gives 

essentially correct relative ages, and probably nearly correct absolute ages as well, which can be used as a basis of intraregional and 

extraregional correlations.

Leland Horberg (1955) radiocarbon dates the Wisconsin events 

as follows: Farmdale, greater than 23,000 to 20,000 B. C.; Farmdale, lowan, and Tazewell complex to 18,000 B. C.; Tazewell to 15,000 

B. C.; "Brady" to 12,000 B. C.; Gary to 10,000 B. C.; Two Creeks to 

9000 B. C.; Mankato to 6000 B. C.; followed by a period extending to 

the present which Horberg informally terms "the postglacial." He 

suggests that the radiocarbon dated Valders drift represents a minor 

advance that occurred shortly after retreat from the maximum position 

attained during Mankato time. Because the Cochrane is not discussed 

as a separate event, the presumption is that Horberg considers it either 

part of the Mankato substage or a postglacial event. R. F. Flint and 

Meyer Rubin (1955) restrict their discussion to pre-Mankato events 

but restate a previous conclusion that the Mankato (with maximum 

estimated roughly at 9000 B. C.) is the correlative of the European 

Fennoscandian substage. Their interpretation of the radiocarbon
310 CONTRIBUTIONS TO GENERAL GEOLOGY

ages for the pre-Mankato events is in essential agreement with 

Horberg's. T. N. V. Karlstrom (1955) suggests, from an assessment 

of critical Alaskan and continental radiocarbon-dated stratigraphic 

sections, the following sequence: Early Wisconsin events, including 

the Farmdale (Leighton and Willman, 1950) and lowan substages, 

beginning before about 35,000 B. C.; middle and late Wisconsin substages beginning about 17,000 B. C. (Tazewell), 13,500 B. C. (Gary), 

10,500 B. C. (Mankato), and 7000 B. C. (Cochrane) ; and Eecent 

glaciations beginning about 3500 B. C. and A. D. 500 ("little ice 

age"), and A. D. 1500 ("lesser ice age"). The Cochrane is correlated 

with an Alaskan glaciation dated between about 7000 and 4500 B. C. 

The supporting data bearing on this correlation will be discussed 

later in this paper. The dated boundaries of the author's absolute 

chronology are placed near culminations of integlacial, interstadial, 

and lesser rank retreatal phases immediately preceding recorded 

periods of significant glacial advance.

In one of his most recently published papers bearing directly on the 

age of the Cochrane, Ernst Antevs (1955a) discusses new pollen and 

radiocarbon data from Canada, which he presents as demonstrating a 

pre-Altithermal age for the Cochrane. He considers that the Cochrane, as a pre-Altithermal event, must be the correlative of the Fennoscandian and thus that the radiocarbon-supported correlation of the 

Mankato and Fennoscandian cannot be accepted. Minor revisions 

are presented for his varve chronology. The Lake Willoughby 

moraine, rather than the St. Johnsbury moraine of Vermont, is made 

the equivalent of the Valders (Mankato), which he now dates around 

16,500 B. C. This figure may be contrasted with his earlier figures 

for the Mankato of around 17,000 B. C. (Antevs, 1953) and of around 

25,000 B. C. (Antevs, 1931). This progressive downward revision

in the length of the varve chronology is not the product of new varve 

data so much as of reestimates of the durations represented by the 

gaps in the varve sequences, and of changes in correlations between 

moraines on the east coast and type sections in the Midwest and in 

northern Europe. The delineation of the precise ice boundaries for 

Wisconsin events from the Midwest to the east coast, as well as the 

transatlantic correlations, remains a subject of some conjectirre and 

of no small controversy. Because of these uncertainties, Antevs' 

figures may be accepted as shrewd first approximations but not

necessarily as precise figures.

PURPOSE OF THIS PAPER

The above brief review of the literature indicates that the Cochrane

problem lies at the center of a basic conflict between the recently derived radiocarbon chronology and the North American varve chronol-
ogy of Mr. Antevs. This conflict can be posed in the form of a question : Is the Fennoscandian the climatic correlative of the Cochrane or 

of the Mankato? A second unresolved question, important for its 

bearing on the precise position of the Cochrane in the late glacial chronology, is whether the Cochrane is pre- or post-Altithermal in age. 

Pertinent data bearing on these two questions will be marshalled below 

in an effort to solve the Cochrane problem. The styratigraphic implications of new radiocarbon results from organic samples collected in 

the Cochrane area will be discussed first. The radiocarbon-derived 

age will then be assessed as to general validity within the framework 

of proposed late-glacial and postglacial chronologies of both North 

America and Europe (pi. 31).

ACKNOWLEDGMENTS

For helpful comments and criticisms offered on preliminary drafts 

of this paper the author is indebted to Bjorn Andersen, of the 

University of Oslo, Norway; V. K. Prest, of the Canadian Geological Survey; and the late Leland Horberg, of the University of 

Chicago. Appreciation is expressed to Hans Suess and Meyer Rubin, 

of the U. S. Geological Survey, for general counsel on the radiocarbon dating of the continental chronology and for laboratory 

analyses of the author's samples. Particular appreciation is expressed 

to Mr. Eubin, who was of great help in interpreting the early and 

middle Wisconsin events discussed in this paper. The author's interpretations are in part the product of information and ideas contributed by others; nonetheless, some uncertainty and general disagreement remain, and the author accepts complete responsibility for 

his conclusions.

The author, like most Pleistocene researchers, is greatly indebted to 

Ernst Antevs, whose early and continued dedication to the difficult 

task of establishing an absolute chronology for North America has 

developed in American geologists an awareness of the philosophy and 

methodologies that may be employed and who has also laid for them, 

by a lifetime of detailed and diversified research, an excellent foundation for subsequent work and continuing progress.

NEW RADIOCARBON DATA BEARING ON THE AGE OP

THE COCHRANE

GEOLOGIC SETTING

The Cochrane moraines occur in an area which is largely underlain by extensive deposits of varved and laminated lacustrine clay 

and silt deposits, locally containing ice-rafted pebbles, cobbles, and a 

few boulders. These deposits constitute the "Clay Belt" of northern 

Ontario and Quebec, and were laid down in an extensive proglacial
312 CONTRIBUTIONS TO GENERAL GEOLOGY

lake (Barlow-Ojibwa) (fig. 55). This lake was largely confined 

'on the south by the Great Lakes-Hudson Bay divide (the height 

of land) and on the north by the retreating margin of the continental 

ice sheet (Antevs, 1925; Flint, 1953). Final drainage of proglacial 

lake waters from the Cochrane area took place when the ice margin 

had retreated far enough north to allow water to escape to Hudson 

Bay.

Ernst Antevs (1953) postulates that glacial lake Barlow-Ojibwa 

was drained before the readvances of the ice margin near Cochrane, 

but the field evidence presented earlier (Antevs, 1925) implies that 

a lake existed, at least locally, during and following the readvances. 

Several exposures of undisturbed surface deposits of laminated silt 

and clay, observed near Cochrane by the author in 1954, are a record 

of lake deposition during final retreat of the ice margin and at a 

time when it lay somewhere to the north of Cochrane. The exact 

position of the ice margin when the lake waters finally escaped into 

Hudson Bay is not evident from the available geologic evidence. The 

answer to this question, and the question as to whether this late proglacial lake history is a natural extension of glacial lake BarlowOjibwa or a separate event, must await the results of the current 

mapping program in northern Ontario by the Canadian Geological 

Survey. The author believes, however, that final drainage of lake 

waters probably did not take place until some time after the ice margin 

retreated north of the Turgeon Bend moraine. This is based on the 

premise that an active ice cap, centered in the Hudson Bay region 

(the Laurentide ice sheet of Flint, 1953) and large enough to reach 

as far south as the Turgeon Bend moraine, would probably have completely filled the Hudson Bay trough and would thus remain, at 

least up to this stage of retreat, an effective barrier to northward

drainage.

Postglacial lake drainage and thus, presumably, post-Turgeon Bend 

events near Cochrane are recorded by peat accumulation in broad

saucorliko depressions, which determine the many poorly drained

muskeg surfaces on the otherwise flat, forested, and cultivated lakebottom plains. Dissection of the bottom land surface has reached 

depths of more than 100 feet along major drainage lines. Frederick

House River crosses the area in a terraced valley cut in, and locally

through, a thick section of laminated clay and silt resting- on till and

glaciofluvial deposits.

SAMPLES COLLECTED FROM BENEATH COCHRANE DRIFT

Two samples from Ontario, dated by the U. S. Geological Survey's 

radiocarbon laboratory, were taken within the area covered by the 

postulated Cochrane readvances. These came from beneath till units 

exposed along a bluff on the Missinaibi River, 6 miles upstream from
PROBLEM OF THE COCHRANE IN LATE PLEISTOCENE CHRONOLOGY 313

the mouth of the Soweska River (loc. 1, fig. 55). The samples were 

collected by 0. L. Hughes and submitted through the courtesy of 

V. K. Prest, both of the Geological Survey of Canada.

Sample W-242 ("W" is the prefix of all samples dated at the Washington U. S. Geological Survey laboratory), peat from a continuous 

layer under 20 feet of surface drift including till, records a preCochrane time when the area was ice free and the climate sufficiently 

ameliorated to allow the growth of vegetation. The age of the sample 

was outside the present range of radiocarbon dating, and a conservative limit was set at greater than 38,000 years. Sample W-241 is 

wood from a gravel layer, underlying the above-mentioned peat layer 

and separated from it by 3 feet of a till-like deposit. This was also 

determined to be greater than 38,000 years old.

Continued work in the Cochrane area may eventually reveal the 

presence of younger organic zones underlying Cochrane drift. However, all available radiocarbon results from uppermost organic beds 

underlying surface drift, both in southern Canada and the northern 

part of the United States, are consistent with the concept that parts 

of Canada were continuously under ice from the inception of the 

Wisconsin glaciation until final dissipation of the continental ice 

sheet. Samples, all of which proved by radiocarbon dating to be older 

than 30,000 years, were collected from surface drift in Toronto (W121), Hillsborough, Nova Scotia (W-157), Port Talbot, Ontario (W100), St. Pierre-les-Becquets section, Quebec (W-189), Bronson, 

Minn. (W-102), and Ironton, Minn. (W-101). As brought out by 

R. F. Flint and Meyer Rubin (1955), the ages of samples (23,000- 

16,000 B. C.) taken from organic zones underlying early Wisconsin 

drift in the United States are consistent with geographic position; 

that is, the older ages occur in the north and the younger in the 

south. This data compels consideration of the Wisconsin glaciation 

as made up essentially of one major phase of advance followed by one 

major phase of retreat, with relatively minor oscillations of the ice 

border during both advance and retreat determining the substage 

events. The evidence of the Cochrane in post-Mankato time fits well 

in this new conceptual framework. The fact that the Cochrane 

oscillations apparently took place in a proglacial lake environment, 

however, minimizes the chance that vegetation zones that may have 

formed before the readvances will be found in the stratigraphic section 

of the Cochrane area.

SAMPLES COLLECTED FEOM SURFACE DEPOSITS IN THE COCHRANE

AREA

Two wood samples were collected by the author in 1954 from a 

peat section directly overlying laminated lake silts, exposed by road 

construction operations on the Trans-Canada Highway about one-
314 CONTRIBUTIONS TO GENERAL GEOLOGY

half mile east of Frederick House River Crossing, west of the town of 

Cochrane (loc. 2, fig. 55).

The exposed mossy peat section, 4-6 feet thick and with permafrost in the lower few feet, directly overlies undisturbed laminated 

lake clays and silt containing a few scattered pebbles. Two distinct 

buried forest layers, with prostrate trunks, limbs, and tree stumps 

in place occur approximately 2 feet and 3y2 feet down in the peat 

section. An upper woody peat bed, about 6 inches to a foot below 

the surface, may represent a third buried forest zone or the root zone 

of a forest no longer present on the wetter parts of the muskeg surfaces. All the woody layers had stratigraphic continuity throughout 

the one-fourth mile length of the exposed peat section. Similarly, 

two woody layers were observed in the upper parts of peat sections 

exposed in shallow drainage ditches of roads crossing other muskeg 

basins in the area. The stratigraphic continuity of these forest layers 

and their presence in many separate peat sections suggest that they 

may record events of regional, rather than local, environmental 

significance.

Sample W-136, wood from the forest layer near the base of the 

peat section, provides a minimum date for drainage of glacial lake 

waters and for the final withdrawal of the ice margin north of 

the Cochrane area. The age of the sample is 6380 ±350 years (4430 

B. C. ±350 years). Sample W-176, wood from the middle forest 

layer, is 5300 ±300 years (3350 B. C. ±300 years) in age, which, 

considering sample W-136, is in agreement with the stratigraphic 

positions of both samples and implies a not unreasonable interval of 

about 1,100 years duration for the accumulation of the intervening foot 

or so of mossy peat.

Peat from the base of a 10%-foot-thick peat section overlying gray 

homogeneous clay near Dugwal, 34 miles due south of Cochrane, 

Ontario, was collected in 1952 by Heikki Ignatius and J. A. Elson. 

The sample (Y-222) gave an age of 6730 ±200 years (4780 B. C. 

±200 years) and is interpreted as providing a minimum date for the 

last glaciation in the Cochrane area (Preston, and others, 1955). 

This sample is consistent in stratigraphic position and age with the 

samples collected by the author near Cochrane.

AGE OF THE COCHRANE AS DERIVED FROM RADIOCARBON DATA

Kesults Of radiocarbon tests of samples collected from the Cochrane

area imply a Cochrane age between 36,000 B. C., or slightly older, and

4500 B. C. The results are consistent with the radiocarbon-dated Mankato and pre-Mankato substages of the Wisconsin and provide a logical 

extension of the Wisconsin chronology, back in time from the maximum (Tazewell in Illinois) to the beginning phases of the Wisconsin
PROBLEM OF THE COCHRANE IN LATE PLEISTOCENE CHRONOLOGY 315

glaciation and forward in time from the post-Tazewell Mankato 

advance that took place late in the Wisconsin retreatal phase. As the 

Valders (Mankato) maximum is dated around 9000 B. C., the Cochrane, as a still later event, may be bracketed between 9000 and about 

4500 B. C. The new radiocarbon data do not permit precise dating of 

the boundary between the Mankato and Cochrane but are consistent 

with a post-Fennoscandian and a pre-Altithermal age for the Cochrane 

events.

CORRELATIVE EVENTS OF THE COCHRANE

Most geologists agree that the concept of worldwide contemporaneity of both large- and small-scale climatic trends is supported 

by the radiocarbon dating of the Two Creeks interval and Allerod 

horizon and by the historically dated glacial advances of the past 

few centuries. Such contemporaneity in climatic trends is slowly 

becoming demonstrable, too, on the basis of long-period weather records. If the radiocarbon-derived Cochrane age is correct, climatic 

events which are directly correlatable should be recorded elsewhere 

in the world. It is believed that glacioeustatic sequences recorded in 

Alaska, northern Europe, and elsewhere demonstrate the post-Fennoscandian age of the Cochrane, substantiate the radiocarbon-based 

Mankato-Fennoscandian correlation, and support the placing of the 

boundary between the Mankato and Cochrane at around 7000 B. C. 

A significant relation between glacial and atmospheric humidity 

changes is revealed by comparing the glacioeustatic history of late 

Pleistocene and Recent events with the recorded drought intervals in 

Western United States and the recurrence surface sequence of southern 

Sweden.

GLACIOEUSTATIC EVENTS IN SOUTH-CENTRAL ALASKA

Results of investigations by the author in south-central Alaska, 

briefly summarized by Karlstrom (1955), indicate a systematic series 

of glacial advances and coincident low-sea-level periods which seem 

to be closely correlatable with oscillations in ice-margin and sea-level 

positions in other parts of the world. A series of ice oscillations recorded by the innermost belt of the Naptowne morainal complex 

of Wisconsin age in Alaska is believed to have coincided with three 

low-sea-level oscillations inferred from coastal bog stratigraphy and 

radiocarbon-dated between 7000 and 4500 B. C. It seems reasonable 

to assume that the Cochrane oscillations are bracketed in the same time 

interval. The Alaskan glacial chronology over the past 12,000 years 

is summarized in plate 31.

A chronology based on eustatic sea-level changes has universal 

application. Insofar as sea-level changes result solely from changes

388997 56 3
316 CONTRIBUTIONS TO GENERAL GEOLOGY

in land-ice volume, they must affect all ocean basins simultaneously 

and thus be recorded by parallel hydrologic changes in all coastal 

areas of the world. However, changes in sea level have demonstrably 

resulted from a multiple of factors, including isotasy and disastro- v 

phism as well as eustasy, and the proof of eustasy is difficult at best. 

One approach, satisfied in part by the Alaskan evidence over the past 

10,000 years, is to prove contemporaneity between regional glacial and 

sea-level changes. A more indirect approach is to demonstrate that 

the postulated sea-level changes simultaneously affected more than 

one ocean basin (and were thus presumably eustatic) rather than hav- * 

ing strictly local geographic expression (thus being presumably diastrophic or isostatic in genesis). Substantiation for the eustatic 

nature of the Alaskan (North Pacific Ocean) sea-level history may 

be found in apparently parallel sea-level changes in the Atlantic 

Ocean, as recorded from the interconnected Baltic sea basin and from 

greater Bermuda. *

SEA-LEVEL CHANGES OF GREATER BERMUDA

Organic samples from submerged cedar forest and peat beds about 

50 feet below present sea level on greater Bermuda gave dates, respectively, of 9550 B. C. ±700 years and 6650 B. C. ±500 years (Kulp, 

1953 ^. The dated peat layer is one of several peat layers intercalated * 

in rnuddv sediments overlying the forest layer. According to Kulp, 

they probably relate to recurring low stands of the sea during initial 

retreat of the continental glaciers from the late Wisconsin maximum 

(Mankato). The Bermuda evidence thus provides a clear record of 

a series of post-Mankato low sea-level phases which are in general- conformity with the comparable part of the Alaskan sequence.

HYDROLOGIC CHANGES IN THE BALTIC BASIN AND THEIR * 

KELATION TO GLACIAL EVENTS

The hydrologic history of the Baltic basin has been worked out 

in some detail (Magnuson, Granlund, and Lundqvist, 1947; Sauramo, 

1939, 1954). It is closely integrated with the Blytt-Sernander climatic sequence derived, from bog stratigraphy, the Swedish pollen 

zones, and Granlund's recurrence zonation in the standard Swedish 

Late-glacial and Postglacial chronology (pi. 31). Although controversy exists on some of the details of this hydrologic history, there is

general agreement that the Baltic basin experienced two major periods of marine transgression after the retreat of the Baltic ice cap ±

margin from the Fennoscandian moraines.

The first transgression of the North Sea into the basin occurred

during the Finniglacial retreat and culminated around 7000 B. C. 

the Rhabdomena stage of the Yoldia Sea (Sauramo, 1939). This 

part of the Yoldia is renamed the Echineis Sea in a more recent paper
PROBLEM OF THE COCHRANE IN LATE PLEISTOCENE CHRONOLOGY 317

(Sauramo, 1954). The second transgression, as represented by the 

Litorina Sea, culminated about 4500 B. C. during the Atlantic climatic period dated between about 5500 and 3000 B. C. These two 

periods of transgression are separated by the Ancylus Lake period, 

during which the marine connection with the North Sea was largely 

or completely disrupted and the Baltic Sea was filled with fresh to 

brackish water. The transition from the Yoldia Sea to Ancylus Lake 

is explained on the basis that isostatic upheaval of Scandinavia, temporarily proceeding at a faster rate than the general Postglacial rise 

in sea level, separated the Baltic basin from the ocean and determined 

an interior lake with restricted,outlets to the ocean. The traditional 

view that the level of Ancylus Lake was higher than the ocean level 

is seriously questioned by Sauramo (1954), who presents evidence 

indicating that the Baltic Ancylus was actually a bay of the ocean, 

its water almost fresh because of the restricted nature of its outlet 

through the Danish Sound. In the light of this and of the new evidence implying essential contemporaneity of the Ancylus Lake period 

with a previously unrecognized eustatic low-sea-level phase as recorded in Alaska and greater Bermuda, it is apparent that the Baltic 

Ancylus could have resulted, completely or in large part, from a 

marine regression that accompanied a regeneration of continental 

and alpine ice masses.

The northern European glacial chronology is generally considered 

to end with bipartition of the waning ice sheet in the vicinity of 

Ragunda (the zero year of the Swedish varve chronology and the 

beginning of the Ancylus Lake period). However, there is recorded 

in the Swedish mountains, near the zero year, a series of- ice-margin 

oscillations (Degeer, 1954; Brooks, 1952) which-may correlate directly 

with the postulated Ancylus period marine regression.

A more detailed sequence of post-Fennoscandian glacial events appears to be recorded in Norway by a distinctive morainal sequence 

(Bjorn Andersen, personal communications). The Norwegian Ra 

moraines are considered to be of Fennoscandian age. Behind these 

moraines are found several pronounced morainal groups, the youngest 

of which belong to the Romeriks-Rigeris morainal system. In many 

valleys the moraines of this system form dams holding in the large 

East Norwegian lakes, and in some fjords these-moraines are directly 

associated with elevated strandlines. The Scandinavian strandline specialists believe that this morainal system corresponds to the 

f-stage in the strandline chronology. The f-strandline, in turn, is 

correlated by Matti Sauramo and others with the Ancylus period in 

the Baltic basin. If this correlation is correct, there is direct 

evidence in Norway of a series of ice oscillations during Ancylus time, 

in agreement with the Swedish glacial record at Ragunda.
318 CONTRIBUTIONS TO GENERAL GEOLOGY

Interpreted in a glacioeustatic sense, there is a striking agreement 

in sequence and time between the major: hydrologic changes in the 

Baltic basin and the radiocarbon-dated glacial sequence of Alaska. 

A similar climatic relationship is apparently recorded from the Cochrane area. According to Antevs (1953) the Cochrane oscillations 

were immediately preceded by a period of rapid retreat (the 

Timiskaming), which therefore appears to be the climatic correlative 

of the Yoldia Sea transgression. As implied by the new radiocarbon 

results, the Cochrane preceded the Altithermal (Atlantic climatic 

period) and thus preceded the culmination of the Litorina transgression dated at 4500 B. C. and the equivalent highest sea-level stand (of 

apparent worldwide record) attained in post-Pleistocene time (Fairbridge, 1950; Stearns, 1945).

POST-COCHRANE BOG RECORD AND CLIMATIC 

HISTORY

The continental glacial history terminates with the final withdrawal of the continental ice margin north of Cochrane. PostCochrane climatic events in Canada must be inferred largely from 

evidence of marine invasions of the Hudson Bay region and from bog 

and pollen stratigraphy (Flint, 1953; Antevs, 1955a). The radiocarbon-dated peat section near Cochrane records three periods during 

post-Cochrane time in which forests invaded bog terrain that had 

previously supported only a mossy plant cover. As present-day 

forests in the area are restricted to the better drained sites surrounding 

the margins of the poorly drained bog area, the suggestion is that the 

buried forest layers may represent drier periods in the past when the 

bog surface supported a more extensive forest cover, either because 

of a regional lowering of the water table, a decrease in atmospheric 

humidity, or both. Comparison of the post-Cochrane bog record 

with the North American and northern European climatic chronologies indicates that the forest beds formed during inferred periods 

of warmer and drier climate, while the overlying peaty beds formed, 

in general, during periods of cooler and wetter climate.

NORTH AMERICAN POST-COCHRANE CLIMATIC CHTtONOTOGY

The most detailed chronology available from North America has

recently been summarized (Antevs, 1955b), The post-Cochrane part

of this chronology is based largely on geoclimatic dating of archeological sites in the arid and semiarid Western United States, its

integration -with the North American varve chronology and with the

northern European Postglacial chronology is derived by a series of 

correlations matching long-continued temperature conditions and

changes as inferred from both glacial and vegetal sequences. Ac-
PROBLEM OF THE COCHRANE IN LATE PLEISTOCENE CHRONOLOGY 319

cording to this scheme post-Cochrane time is subdivided into three 

main temperature ages: the Anathermal (period of rising temperatures, 8000-5500 B. C.), the Altithermal (period of maximum temperatures, 5500-2000 B. C.), and the Medithermal (period of 

decreasing temperatures, 2000 B. C. to present). The time boundaries applied to these temperature ,ages, like those for the Cochrane 

oscillations, are derived by Ernest Antevs from correlations with the 

presumably equivalent temperature ages inferred from the dated 

Swedish chronology. In contrast, the drought periods that subdivide 

the cool, wet Medithermal age are independently dated on the basis of 

dendrochronologic, archeologic, and selected radiocarbon data. These 

divisional periods are the Fairbanks drought (ca. 500 B. C.), the 

Whitewater drought (A. D. 330), the Great drought (A. D. 1272- 

1299), and an unnamed drought (A. D. 1573-1593). Despite his use 

of radiocarbon data in dating the Fairbanks drought, many radiocarbon datings of climatic events in Western United States are discarded by Antevs as spurious because they do not agree with the results obtained through his correlations of inferred temperature ages. 

He contrasts the independently,dated drought periods with the major 

high-temperature Altithermal period (also referred to as the Long 

drought) and considers that these periods represent changes in, and 

conditions of, moisture which cannot be used for long-range correlations because of limiting geographic factors.

Of direct significance for the purposes of this paper is Antevs' 

(1955a) correlation of the forest succession of Mont Tremblant Park, 

Quebec, with his absolute chronology (fig. 56). Pollen studies of 

bog and lakelet deposits in Mont Tremblant Park (Potzger and 

Courtemanche, 1954) indicate a forest succession of five different 

forest types from which the following climatic changes are inferred: 

Forest type I (Avarm climate) ; Forest type II (cooling climate); 

Forest type III (warm, dry, climate, xerothermic age) ; Forest type 

IV (cool and wet climate) ; and Forest type V (cooler, perhaps wetter 

climate). Based on the inferred temperature changes and the fact 

that the pollen record is obtained from an area lying to the south of 

the Cochrane moraines, Forest Type I is correlated with the Timiskaming retreat; and type II, with the-Cochrane halt. Forest type 

III is correlated with all of the Anathermal and part of the Altithermal age. Type IV is correlated with parts of the Altithermal and the 

succeeding Medithermal age. Boundaries between Forest types III 

and IV and between Forest types IV and V are dated, respectively, 

about 4000 B. C. and just before the beginning of the Christian era.

This correlation is used by Antevs as independent evidence of the 

pre-Altithermal age of the Cochrane and thus as supporting evidence 

for the correlation of the Cochrane with the Fennoscandian. As
320 CONTRIBUTIONS TO GENERAL GEOLOGY

Time scale

A.D.1000-

0-

1000 B.C.-

2000 B.C.-

3000 B.C.-

4000 B.C.-

5000 B.C.-

6000B.C.-

7000 B.C.-

8000 B.C.-

9000 B.C.-

10.000 B.C.-

.c

_ i

1 s

o> «J

o> 

O

 '

Antevs(1955a)

Mont TremblAnt Park forest 

succession , and inferred 

climatic zones

(Potzger and Courtemanche, 1954)

Wet

Dry

Wet 

Dry 

Wet

Dry

Wet

Dry

Wet

L 

Altithermal

(Maximum 

warmth)

Anathermal

(Increasing

warmth)

 

Cochrane

(Cool)

Timiskaming

retreat

(Warm)

//

/

/

1

1

1

'

1

1

1

1 ' 1

. /

1 '

1

/

1

Forest type 

V 

Spruce, fir, 

northern

hardwoods

Forest type

IV

White and

red pine,

hemlock

 _

Forest type 

III

Jack pine 

maximum

Forest type

II

Fir, spruce

Forest type

I

Jack pine, birch,

Cooler, 

perhaps 

wetter

 Cooling 

and wet

_ _ _

Warm ( dry

"Xerothermic" 

age

Cooling

Relatively

warm

white and red /^' N \AA/

pine, oak /

 

Present report

...7 ...

 o

O

cu

00

O 

_o

c 

ra

0

O

1

o

Q-

-A

0.5 to 1 ft 

mossy peat 

(Wet)

Forest zone (Dry)

 

1 to 1.5 ft

mossy peat 

(Wet)

 Forest zone (Dry) 

W-176 3350 B.C.

1.5 ft mossy peat 

(Wet)

 Forest zone (Dry) 

W-136 4430 B.C.

0.5 ft peat -^ AX\-A v-vvv-w^/

Cochrane

Timiskaming

___ _ _ __

Mankato

substage

FIGURE 5i6. Correlation of the Mont Tremblant Park, Quebec, forest succession with the 

North American geoclimatic chronology.

discussed in this paper, the Cochrane is indeed pre-Altithermal but

is also post-Fennoscandian. As shown in figure 56 the Mont Tremblant Park forest sequence would appear to be fully consistent with 

this interpretation and with the radiocarbon-dated Cochrane bog record. As dated, the two lower forest layers fall near the middle of the 

Altithermal age and appear to represent two periods of maximum
PROBLEM OF THE COCHRANE IN LATE PLEISTOCENE CHRONOLOGY 321

dryness near the culmination of maximum postglacial warmth. 

They may thus be logically correlated with the xerothermic age as 

represented by Forest type III. Therefore, overlying mossy peat 

beds, as correlatives of the periods represented by Forest types IV and 

V, appear to have been deposited at a time of generally increased 

moisture and decreased temperatures. The uppermost undated forest bed in the Cochrane bog seemingly records an important but temporary shift toward drier conditions which, in the Mont Tremblant 

Park area, may be represented by the transition from Forest type IV 

to V. This transition is dated by Ernst Antevs as just before the 

beginning of the Christian era, which appears to make it the equivalent of the Fairbanks drought period (ca. 500 B. C.) recognized in 

Western United States. Interestingly enough, the post-Atlantic 

(Altithermal) period of maximum dryness recognized in the European chronology also falls just before the beginning of the Christian 

era (that is, ca. 600 B. C.). The Swedish record of moisture changes 

in Postglacial time is one of the most detailed and accurately dated 

climatic chronologies available from Europe and will be discussed in 

some detail.

RECURRENCE SURFACE SEQUENCE OF SWEDEN

The detailed Swedish record of Postglacial changes in atmospheric 

humidity is largely derived from stratigraphic studies of raised bogs 

in southern Sweden. Erik Granlund (1932), in his fundamental contribution to an understanding of raised-bog formation, describes a 

series of stratigraphic boundaries or recurrence surfaces (Ry). Each 

recurrence surface records a return to moister conditions and renewal 

of peat growth after a period of stability and humification of the bog 

surface. In a study of hundreds of bog sections, Granlund found that 

owing to peculiar local conditions some bogs contained no recurrence 

surfaces, whereas others contained several. By using pollen and 

archeological evidence for correlation and absolute dating, he demonstrates that the recurrence boundaries group around five different 

stratigraphic levels, which are dated as follows: Ry I, ca. A. D. 1200; 

By II, ca. A. D. 400; Ey III, 600 B. C.; Ry IV, 1200 B. C.; Ry V, 

2300 B. C. Recurrence surface III represents a major climatic break 

in the Swedish sequence and marks the boundary between the major 

sub-Boreal and sub-Atlantic phases of the Blytt-Sernander climatic 

sequence. This event is also considered to be the correlative of the 

Grenzhorizont (Weber, 1910), a major period of bog drying recognized in the stratigraphy of north German bogs and for a time considered to represent all of sub-Boreal time.

Although Erik Granlund found no recurrence surfaces older than 

2300 B. C., he considers that the recurrence phenomenon is reflected
322 CONTRIBUTIONS TO GENERAL GEOLOGY

in the pollen spectra throughout Postglacial time, which he subdivides 

into a series of recurrence zones. Recurrence zone boundaries below 

Ry V are correlated with the upper part of pollen zone IV; the boundary between pollen zones IV and V; pollen zone VI, or the transition between Ancylus Lake and Litorina Sea; pollen zone VIII, which 

marks the beginning phase of Ancylus Lake; and the transition between pollen zones IX and X (transition between the Baltic ice lake 

and Yoldia Sea periods). Subsequent work in northern Europe revealed the presence of additional Recurrence surfaces (Nilsson, 1935; 

Von Post, 1946).

The generally accepted Swedish Postglacial chronology now includes Mr. Granlund's original recurrence surface sequence plus two 

older surfaces, dated ca. 2900 (Ry VI) and 3500 B. C. (Ry VII). 

According to this chronology Mr. Granlund's recurrence boundary 

between zones 6 and 7 as presented in his 1932 paper corresponds to 

Ry VI, VII occurs within zone 7, and the older recurrence boundaries 

are dated about 4600 B. C., between 5800 and 5500 B. C., between 7000 

and 6500 B. C., and about 8000 B. C.

As each recurrence surface represents a change from drier to moister 

atmospheric conditions, the dated series records recurring dryness at 

general intervals of 500-600 years and 1,000-1,200 years, and supports 

the concept of a fundamental climatic cycle with a periodicity of about 

550 years and a tendency for a stronger impulse at about 1,100-year 

intervals. As dated, it is evident that Mr. Grunlund's recurrence-zone 

boundaries appear to reflect the same general periodicity. According 

to Deevey (1953) the recurrence surfaces, representing cycles of alternating drought and moisture, are known to have been approximately synchronous throughout Europe since about 2300 B. C. Similar cycles of drying and bog generation appear to be recorded in many 

of the North American bogs as well, but no attempt has been made 

to correlate specific North American events with those of this European 

sequence.

The conformity of the Postglacial climatic history of Europe, as 

represented by the recurrence sequence, with that of North America

was first appreciated by the author from a comparison of the Swedish 

record with the radiocarbon-dated Alaskan glacial sequence (pi. 31). 

Nearly all the recorded periods of increased atmospheric humidity 

in Europe are matched by periods of glacial advance in south-central 

Alaska. The consistency of the two records, although not perfect, 

is sufficient to support strongly the concept of parallel climatic histories as directly expressed by essentially synchronous changes in atmospheric conditions. Thus W. H. Ahlmann's suggestion (1953) that 

the periods of increased atmospheric humidity, as represented bj the 

intervals between recurrence surfaces, may have favored glacial ad-
PROBLEM OF THE COCHRANE IN LATE PLEISTOCENE CHRONOLOGY 323

yances would appear to be fully supported by the glacial record in 

Alaska. Although Antevs (1955b) considers that long-range correlations of moisture conditions and changes are not possible because of 

restricting geographic factors, the Western United States drought 

periods are essentially contemporaneous, as dated, with comparable 

periods recorded in the Swedish and Alaskan sequences. His Fairbanks, Whitewater, and Great droughts closely correspond in time 

and sequence with K-y I, II, and III and with the equivalent periods 

of glacial retreat in Alaska.

The conformity in climatic record between such widely separated 

areas as northern Europe, Western United States, and Alaska is 

all the more striking because of the greatly differing climatic zones 

and types of geologic records and because the corresponding climatic 

events in all three regions were independently and internally dated; 

that is, not dated by extraregional correlation of apparently similar 

sequences of events. The record for Western. United States is one of 

inferred changes in moisture affecting alluvial and soil processes in 

a continental semiarid or arid environment. The record for Sweden 

is one of moisture changes affecting the formation of raised bogs 

in an extremely wet, cool, maritime environment. In contrast the 

south-central Alaskan record is one of climatic trends affecting the 

regimen of alpine glaciers in a somewhat colder, modified maritime 

environment. The drought events of the Western United States are 

dated by a combination of dendrochronologic, archeologic, and radiocarbon data; those of Sweden, largely by historical cross dating, with 

refinements of dating made possible by complete integration within 

the varve, pollen, and hydrologic sequences of the Scandinavian Postglacial chronology. The dates applied to the Alaskan events are 

derived exclusively from radiocarbon stratigraphic data.

A significant climatic cycle widespread, if not universal involving 

changes in atmospheric humidity is thus implied. It is, then, not 

surprising that the radiocarbon-dated post-Cochrane bog sequence, 

by its alternation of forest and mossy peat beds, appears to record 

major events of this same humidity cycle. As previously discussed, 

the dated forest zones fall within the age boundaries of the generally 

recognized Postglacial period of maximum warmth (essentially the 

Atlantic period of the Scandinavian climatic chronology), which in 

this country has been variously referred to as the Altithermal, Thermal Maximum, or xerothermic age. More significantly, both dated 

forest layers (4430 B. C. ±350 years and 3350 B. C. ±300 years) 

appear to represent 2 periods of drier conditions about 1,100 years 

apart which, within the statistical limits of counting error, can be 

considered contemporaneous with the drought periods marked by the 

Swedish recurrence boundaries dated around 4600 and 3500 B. C.
324 CONTRIBUTIONS TO GENERAL GEOLOGY

The stratigraphy of the post-Cochrane bog thus appears to represent a North American bog-drying sequence which closely parallels 

that inferred from the Swedish evidence and to provide direct evidence 

of climatic subdivision, heretofore unrecognized, of the Altithermal 

period and the correlative period of major glacial retreat in Alaska. A 

similar threefold subdivision of the Timiskaming retreat is implied 

by direct correlation with the Swedish recurrence sequence. Recurrence boundaries dated ca. 7000 and 8000 B. C. fall near the beginning 

and end of the Timiskaming retreatal period as dated in this paper 

and presumably represent intervals of more rapid retreat immediately following the last Mankato oscillation and immediately preceding the maximum Cochrane advance. A mid-Timiskaming interval 

of increased atmospheric humidity ca. 7500 B. C. has not yet been 

formally recognized from North American climatic data. However, 

insofar as a climatic trend toward increased atmospheric humidity 

could be expected to determine a retardation in the rate of glacial 

retreat, a halt, or even a readvance of the ice margin, it is possible that 

the post-Mankato, pre-Cochrane Pembroke moraine near Mattawa, 

Ontario, as described by Antevs (1953), may provide evidence of this 

mid-Timiskaming climatic event.

The combined geoclimatic data from Alaska, northern Europe, 

Canada, and Western United States are consistent with the generally 

accepted post-Mankato glacial history of general retreat to a postglacial minimum centered in the Altithermal (Atlantic) followed by a 

period of general glacial regeneration (essentially the "little ice age" 

of Matthes). The presented data further indicate that the post-Mankato period is subdivisible into a cyclical series of secondary glacial 

retreats and advances superimposed on the broader glacial record. 

These secondary glacial events show a direct relation to changes in 

atmospheric humidity as independently inferred from dated geoclimatic records and appear to record a fundamental climatic cycle with 

a base periodicity of about 550 years and with a stronger recurrence 

about every 1,100 years. Whether these cyclical changes in atmospheric humidity resulted primarily from temperature changes or from 

precipitation changes is uncertain. It is believed, however, that precipitation may have been the primary meteorological factor with lower

temperatures resulting as a secondary factor from increased cloudiness during the recorded intervals of higher atmospheric humidity,

glacial advance, and marine regression.

Although the chronology proposed in this paper appears internally

consistent with the basic geologic data from both Europe and North

America, it seemingly contradicts the climatic history traditionally

applied to the Boreal (warm and dry), Atlantic (warm and wet), 

and sub-Boreal (warm and dry) periods of the European Blytt-
PROBLEM OF THE COCHRANE IN LATE PLEISTOCENE CHRONOLOGY 325

Sernander classification as most recently presented by Deevey (1953). 

The inferred warm, dry climates for both the Boreal and sub-Boreal 

periods is difficult to reconcile with the glacioeustatic evidence of general glacial advances which seems to require either increased precipitation, lowered temperatures, or both, for the Boreal and sub-Boreal 

periods, relative to the intervening Atlantic period. The BlyttSernander climatic inferences are fundamentally derived from stratigraphic evidence of topogene (lake-basin) bog types present in the 

coastal areas of Sweden. The bog record indicates generally lower 

lake levels (ground-water levels) during the Boreal and sub-Boreal 

periods, and generally higher lake levels during the intervening Atlantic period (Magnusson, Granlund, and Lundqvist, 1949, p. 368). 

The inference of relative dryness for Boreal and sub-Boreal time 

therefore appears to be based on the assumption that intervals of 

lower lake levels must equate with intervals of lower atmospheric 

humidity. Consideration of the geologic environment of the coastal 

Swedish bogs and the hydrologic history of the adjacent Baltic basin 

suggests that this interpretation is not the only, nor the most likely, one 

to be drawn.

Alaskan stratigraphic studies indicate two types of lake-basin bog 

records that must be interpreted in an opposite geoclimatic sense. 

Type I (coastal lowland topogene bogs) records higher lake levels 

during periods of glacial retreat and lower lake levels during periods 

of glacial advance. In contrast, type II (upland topogene bogs), like 

the raised-bog or ombrogene bog type used by Granlund (1932) in his 

recurrence surface studies, records the reversed hydrologic relations 

to glacial change. Type I is genetically related by the control of base 

level on regional ground-water levels in humid areas to the eustatic 

controlled Thalassostatic terrace type, and type II to the more directly 

atmospheric controlled Climatic terrace type as described by F. E. 

Zeuner (1950). The Blytt-Sernander climatic classification, based as 

it is largely on this coastal lowland topogene bog record, may thus be 

interpreted more directly in terms of glacioeustatic rather than atmospheric humidity changes. By this interpretation the Boreal and 

sub-Boreal intervals of lower lake levels become periods of generally 

increased atmospheric humidity (cool and wet rather than warm and 

dry) relative to the Atlantic interval of higher lake levels as a period 

of generally decreased atmospheric humidity (warm and dry rather 

than warm and wet) in general agreement with the North American 

geoclimatic data,

RANK AND GEOLOGIC AGE OF THE COCHRANE

The rank and geologic age of the Cochrane in late Pleistocene 

chronology has long been in dispute. As previously discussed the
326 CONTRIBUTIONS TO GENERAL GEOLOGY

Cochrane has been variously considered the last substage of the Wisconsin, possibly a late phase of the Mankato substage, and a postWisconsin event. The rank of a geologic event must be assessed 

largely on the basis of intensity and duration as related to other 

comparable events of established rank status. The relative intensities of a series of glacial events may be roughly established by comparison of distances between moraines and estimated distances covered 

during advances. Relative durations may be determined by dating 

boundaries between advances.

Distances between end moraines of the Wisconsin substages, including the Cochrane moraines, are as follows: Tazewell to Gary, 130 

miles; Gary to Mankato, 130 miles; Mankato to Cochrane, 400 miles. 

Estimated minimum distances of advance to maximum position are 

given for the Lake Michigan lobe by Horberg (1955) as follows: 

Farmdale, 300 miles; lowan, 400 miles; Tazewell, 250 miles; Gary, 

445 miles; and Mankato (Valders maximum), 100 miles. Antevs 

(1953) estimates that a distance of about 70 miles was covered by 

the maximum readvance of ice in the Cochrane area to Nellie Lake. 

Assessment of recent radiocarbon results (Karlstrom, 1955) implies 

a time difference ranging from 3,000 to 4,000 years between substage 

events throughout the late Pleistocene and Recent. As dated in this 

paper, the Cochrane is from 2,000 to 4,500 years younger than the 

Valders maximum. As the Cochrane readvances are dated by maximum and minimum ages, the Cochrane maximum must fall between 

these dates. Thus on the basis of relative morainal positions, estimated distances of readvance, and temporal relations, it appears that 

the Cochrane is comparable to the earlier substage events of the Wisconsin and should therefore be considered an event of substage rank 

within the standard Pleistocene chronology. O«/

Whether the Cochrane should be considered Wisconsin or PostWisconsin in age depends largely on the placement of the upper boundary of the Pleistocene epoch in the standard continental chronology. 

In this country there are at present two major schools of thought on 

this problem. C. B. Hunt (1953), among others, retains the traditional concept of the Recent as a geologic time interval of epoch rank 

following the Wisconsin glacial stage of the Pleistocene epoch and 

considers that stratigraphic and faunal evidence from Western United

States strongly supports using the Altithermal interval as the boundary between the two epochs. Flint (1949), among others, considers 

that the extent of present glaciers and ice caps indicates that we are

still in the ice age and thus still in the Pleistocene epoch. He equates

Recent with postglacial time which he distinguishes from the formalized Postglacial period in the Scandinavian chronology and considers that both terms are only of local value, of subordinate stratigraphic
PROBLEM OF THE COCHRANE IN LATE PLEISTOCENE CHRONOLOGY 327

importance, and that both should be used only in an informal way. 

In Flint's classification we are still in the Wisconsin age, and the 

Altithermal (his Thermal Maximum) is considered to be a subordinate 

event within the Mankato substage. The author's research on Pleistocene chronology and climatic controls strongly suggests yet another 

possibility. By this concept the Altithermal is considered to fall near 

the culmination of an interglacial period which separates the Wisconsin glacial stage from a still unnamed glacial stage that may attain 

its maximum extent within the next 20,000 years. A similar conclusion was suggested by Cesare Emiliani (1955) in his study of ocean 

temperature changes as recorded in deep sea cores from the Atlantic 

and Pacific Oceans. No matter which concept of the Altithermal is 

accepted it is evident that the Cochrane, because it precedes the Altithermal, must be considered of Wisconsin age.

SUMMARY AND CONCLUSIONS

The radiocarbon samples from the Cochrane area which are discussed in this paper broadly bracket the Cochrane oscillations between 

greater than 36,000 and just before 4500 B. C. These results form a 

consistent sequence with the radiocarbon dates obtained for the intervening substage events of the Wisconsin glaciation. Because the 

Cochrane is post-Valders maximum, it may be dated between 9000 

and 4500 B. C. Thus dated, the Cochrane can be correlated with a 

glaciation and low eustatic sea-level phase recorded in south-central 

Alaska (7000-4500 B. C.) and with the post-Fennoscandian, pre-Atlantic Baltic Ancylus Lake period (Boreal, 7000-5500 B. C.) of the 

Swedish Postglacial chronology. Corroborative evidence for parallel 

climatic histories for continental North America, Alaska, and 

northern Europe is found in the apparent agreement between Granlund's humidity ^cycle, as represented by his dated recurrence sequence, 

and the glacial and climatic events recorded in Alaska, Canada, and 

Western United States. His recurrence boundaries (drought periods) 

dated around 7000 and 4600 B. C. closely bracket the Cochrane oscillations as dated in this paper and coincide with the end of the preCochrane Timiskaming period of rapid glacial retreat and with the 

oldest period of bog drying, as represented by the lower radiocarbondated forest layer in the post-Cochrane bog sequence near Cochrane. 

Comparison of relative morainal position, estimated distances of readvance, and temporal relations imply that the Cochrane is comparable in rank to the Mankato and earlier Wisconsin substage events. 

Its pre-Altithermal age would appear to require that the Cochrane 

be accepted as a substage event of Wisconsin age.

A fundamental conflict between the independently derived radiocarbon-dated and varve-dated Wisconsin glacial sequence is apparent
328 CONTRIBUTIONS TO GENERAL GEOLOGY

from a direct comparison of the two chronologies as summarized in 

this paper. Antevs discounts the validity of the radiocarbon chronology on the basis that the radiocarbon ages do not agree with the 

ages derived from his varve sequences. His chronology is based on 

a broken varve sequence and tied to the present by a transatlantic correlation of the Cochrane with .the varve-dated Fennoscandian substage of Europe. Beyond the question of whether the correlation of 

the Cochrane with the Fennoscandian is valid, the many gaps in the 

North American varve sequence, and possible errors in cross dating 

separate varve sections and in correlations of moraines, require acceptance of the derived varve ages of Wisconsin events as perhaps 

shrewd first approximations but not necessarily as true figures.

In opposition to the North American varve chronology, available 

radiocarbon data substantiate the stratigraphic correlation of the 

Fennoscandian with the Mankato and the varve date of ca. 8800 B. C. 

for the Fennoscandian substage. The validity of the correlation of the 

Mankato with the Fennoscandian is further supported by the radiocarbon results presented in this paper, which imply the correlation 

of the Cochrane as a post-Mankato and pre-Altithermal event, with 

a post-Fennoscandian and pre-Atlantic glaciation and marine regression. The essential agreement in time and sequence between the discussed radiocarbon-dated events of North America and comparable 

varve, pollen, and archeologically dated climatic events of Northern 

Europe provides additional evidence of parallel climatic histories and 

argues strongly for acceptance of properly interpreted radiocarbon 

results in a near-absolute, as well as a relative, sense. Such acceptance requires that the Cochrane-Fennoscandian correlation be discarded as untenable and that all absolute chronologies directly or 

indirectly based on this transatlantic correlation be reappraised in

the light of available geologic and radiocarbon evidence. In reaching 

this conclusion, the author recognizes that individual radiocarbon

results may give rise to erroneous geologic interpretations but feels 

that sufficient radiocarbon data is now available to provide a satisfactory test of the accuracy of the analytical method and of the derived 

geologic interpretations.

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INDEX

Page

Abstract..__.__.____....____-__ 303 

Acknowledgments_....-.--__--------- 311

Age of the Cochrane.___..._______ 325-327 

Alaska, glacioeustatic events in.------------ 315-316

Alaskan glaciation, correlated with Cochrane. 310 

Allcrod horizon........................ 307,308,315

Altithermal temperature age.... 308,318,319,323,327

Anather.mal temperature age........ --------- 319

Ancylus.Lake period... .__.......... 317,322

Atlantic climatic period..___ 308,317,318,323,325

Baltic Sea basin.............................. 316

Barlow-Ojibwa.-- -_--- 311-312

Bermuda, greater, sea-level changes of__.-.- 316 

Bibliography......---.-....,. .......... 328-330

Blytt-Sernander climatic sequence_ _- 316,321 

Bog record, post-Cochrane_-----.-...-... 318-325

Boreal period..-...--------......--------- 324,325

"Clay Belt".................................. 311

Climatic conditions, history...______ 318-325 

Climatic Optimum..-..........---.--.-.-.-.. 308

Climatic terrace type_.._._---...__ 325 

Conclusions-..--------.------------------- 327-328

Correlative events of the Cochrane...------ 315-318

Droughts...-.-.-....-. .................. 319,323

Echineis Sea....---.--.--.....-.--.-..-..-.- 316 

Evidence for the Cochrane______ 304-305

Fairbanks drought......................... 319,323

Fennoscandian moraines--..... .__---- 316,319

Firmiglacial retreat---------......-----.-----. 316

Forest succession of Mont Tremblant Park... 319 

Frederick House River.------------_-... 304,312

Frying Pan River drainage, age of glacial deposits in area of__-..---.. . 309

Glacioeustatic events in Alaska:... . 315-316 

Great drought-.----------...-----._... 319,323

Harbor Hill moraine.... -. .- 306,307

History of Coclirane problem-.------------ 306-310

Hudson Bay, escape of proglacial lake waters 

" to 312

Introduction.......-...----.------------ 304-311

Lake Michigan lobe...-.--....-...-..----- 320

Lake Willoughby moraine - . 310

Laurentide ice sheet.......................... 312

"Lesser ice age".-------------------------- 308,310

Litorina Sea. 317,318,322,324

"Little ice age". 308,309,310

Page 

Mankato moraine.._......__..... 304,310,326

Medithermal temperature age.. -..__-.... 319

Missinaibi River, sample collected for radiocarbon dating along__......._ 312

Mont Tremblant Park, forest succession of.... 319

Naptowne morainal complex..._____.__ 315 

Nellie Lake:...... .. ... . 304,326

New Britain moraine.-...--..............._ 307

Pembroke moraine. ______________ 324 

Post-Cochrane bog record and climatic history 318-325 

Purpose of paper..___ .___-..-. 310

Ra moraines ______. ___.____ 317 

Radiocarbon dating.. . 307-308,309,311-315 

Rank of the Cochrane__..._________ 325-327 

Recurrence surface sequence of Sweden..... 321-325

Rhabdomena stage._______.______ 316 

Romeriks-Rigeris morainal system___...... 317

Ronkonkoma moraine. .__.________ 306

St. Johnsbury moraine, Vermont __ 306,307,310 

Salpauselka' moraines_.....-.--.-......--... 307

Samples collected from beneath Cochrane

drift for radiocarbon dating..... 312-313

Samples collected from surface deposits in the 

Cochrane area for radiocarbon 

dating.... 313-315

Scanian halt. .__...___....______ 306

Sea-level changes __ 308

Strandline chronology.. -------... 317

Summary..__...__.___ ____ 327-328 

Suskequa River.. .-.. -----. 304

Thalassostatic terrace type. - - 325 

Thermal-Maximum........... ...... 308;323,327

Timiskaming retreat. 318,324

Turgeon Bend moraine.------ ---.--- --- 304,312

Two Creeks formation... . 307,308,315

Valders moraine.. 304,310,326 

Varve chronology.....------- 307,308,310,317,318

Whitewater drought..--------------------- 319,323

Wisconsin events, correlated with European

sequence. 306

radiocarbon dating by Leland Horberg . 309

Yoldia Sea......... -. 316,318,322

Xerothormic period ..... . . 308,323

331

U. S. GOVERNMENT PRINTING OFFICE: 1956