Progressive westward expansion of North American ... · Waters (eds.) Paleoamerican odyssey, Center...
Transcript of Progressive westward expansion of North American ... · Waters (eds.) Paleoamerican odyssey, Center...
Figure 2. Paleo-ice flow patterns Laurentide ice sheet,Foothills Erratics Train’ andlocation of Del Bonita uplandunglaciated area surroundedby terminal moraine.
Progressive westward expansion of North American continental ice sheets during the Quaternary and implications for the timing of initial human overland migration into the AmericasLionel E. Jackson, Jr. Geological Survey of Canada, Vancouver, B.C. and Department of Earth Sciences, Simon Fraser University, Burnaby, B.C., Canada. E-mail: [email protected]
ORIGIN OF THE ICE-FREE CORRIDOR CONCEPT AS AN EXPLANATION FOR INITIAL PEOPLING OF THE AMERICAS
The discovery of the Folsom and Clovis sites in 1927and 1932 respectively provided indisputable evidence of the co-existence of humans with extinct ‘ice age’ fauna. The question immediately arose as to how these hunters had reached the mid-latitudes of North America at a time when the northern half of the continent was apparently buried beneath the Laurentide and Cordilleran ice sheets. In 1933, W.A. Johnston (GSC) proposed that people could have reached the lands south of the ice via a passage between the montane and continental glaciers at the climax of the last glacial maximum (LGM). In 1935, Ernst Antevs coined the term 'ice-free corridor'. Testing of the existence of an ice-free corridor at the LGM was not completely settled until the advent of cosmogenic exposure dating of the Foothills Erratics Train (Fig. 1; Jackson et al. 1997). This in turn begged the question: “was to whether this coalesence was one of many coast-to-coast glaciations or a single unique event”. This question is now resolved based upon applications of advances in glacial sedimentology, AMS 14C dating and paleomagnetic investigation of glacial sediments (Jackson, Andriashek and Phillips, 2011).
ICE-FREE CORRIDORS ARE STILL OPTIONS FOR EARLY OVERLAND
ENTRY OF HUMANS INTO THE AMERICA--- BUT DURING ITS
CLOSING, NOT OPENING
Archaeological sites clearly predating the Clovis culture such as Paisley Cave in North America and Monte Verde in South America apparently predate the opening of a post-LGM ice-free corridor in the coast-to-coast ice covering Canada at the time. This has bolstered the idea that humans entered the Americas along the Pacific Coast.
However, older and, to some, controversial sites such as Meadowcroft (Adovasio and Peder, 2013), Cactus Hill (McAvoy and McAvoy,1997) and clusters of sites in the mid-west summarized by Holen and Holen (2013) (Fig. 6) support the presence of humans south of the ice sheets during the the LGM or earlier during the mid-Wisconsin (OIS 3). Humans occupation north of the Arctic Circle in western Beringia is now well established (Pitulko et al., 2013). Lifeways capable of allowing humans to flourish in the most rigourous periglacial conditions had been achieved by that time. Westward radiation of these people to eastern Beringia would have brought them into one or both of the ice-free corridors (Fig. 6) and the Americas to the south. If and when there is a consensus that humans were in the Americas prior to the LGM, ice- free corridors predating the coalesence of Cordilleran and Laurentide ice and indeed, the interior plateaux and valley systems of the Canadian Cordillera are viable overland routes of entry into the Americas (Jackson and Duk-Rodkin, 1996). Such passages may have existed until ca. 23,000 years ago or even later based upon the youngest pre-LGM ice-free 14C ages from the Interior Plains and the Cordillera.
Adovaso, J.M. and Pedler, D.R. (2013). Chapter 29. The ones that still won’t go away: more biased thoughts on the pre-Clovis peopling of the New World. C.V. Ketron and M.R. Waters (eds.) Paleoamerican odyssey, Center for the First Americans, College Station,
p. 511-520. Barendregt, R.W. and Duk-Rodkin, A.(2011). Chronology and extent of Late Cenozoic ice sheets in North America: A magnetostratigraphic assessment. In J. Ehlers and
P.L. Gibbard, editors: Quaternary glaciations--extent and chronology, Part II: North America. Developments in Quaternary Science, 2. Elsevier, Amsterdam, p. 1-8.Barendregt, R.W., Enkin, R.J. and Tesler, D.L. (2012). Magnetostratigraphy of Late Neogene Glacial, Interglacial,and Preglacial sediments in the Saskatoon and Regina areas, Saskatchewan, Canada. Studia Geophysica Et Geodaetica, 56 (2012), 705−724.Barendregt, R.W., Andriashek, L.D. and Jackson, L.E.(in press). Evidence for Early Pleistocene Glaciation obtained from borecores collected in East-Central Alberta, Canada. Abstracts, American Geophysical Union 2014 Fal l
meeting. Davis, N.K., Locke, W.W. III, Pierce, K.L., and Finkel, R,C. (2006). Glacial Lake Musselshell: Late Wisconsin slackwater on the Laurentide ice margin in central Montana,
USA. Geomorphology: 75, 330– 345.Fullerton, D.S., Colton, R.B., and Bush, C.A. (2004). Limits of mountain and continental glaciations east of the Continental Divide in northern Montana and northwestern
North Dakota, U.S.A. In: J. Ehlers and P.L. Gibbard (eds.), Quaternary glaciations—extent and chronology, part II. Developments in Quaternary Science 2b: North America.. Elsevier, Amsterdam, 131-150.
Holen,S.R. and Holen, K. (2013). Chapter. 25 The mammoth steppe hypothesis: the middle Wisconsin (oxygen isotope stage 3) peopling of North America. In K.E. Graf, C.V. Ketron and M.R. Waters (eds.) Paleoamerican odyssey, Center for the First Americans, College Station,
p. 429-444. Jackson, L.E. Jr. and Duk-Rodkin (1996). Quaternary geology of the ice-free corridor: glacial controls on the peopling of the New World. In: T. Akazawa and E. J. E.
Szathmary (eds.) Prehistoric Mongoloid dispersals. Oxford Science Publications, Oxford, 214-227.Jackson, L.E. Jr. and Little, E.C. (2004). A single continental glaciation of Rocky Mountain Foothills, south-western Alberta, Canada. In: J. Ehlers and P.L. Gibbard (eds.),
Quaternary glaciations—extent and chronology, part II. Developments in Quaternary Science 2b: North America. 29-38.Jackson, L.E. Jr., Andriashek, L.D. and Phillips, F.M. (2011). Limits of Successive Middle and Late Pleistocene Continental Ice Sheets, Interior Plains of Southern and Central Alberta and Adjacent Areas. In J. Ehlers, P.L. Gibbard and P.D. Hughes, editors: Developments in Quaternary Science, Vol. 15, Amsterdam, The Netherlands, 2011, pp. 575-589.Jackson, L.E. Jr., Phillips, F.M., Shimamura, K. and Little, E.C. (1997). Cosmogenic 36Cl dating of the Foothills erratics train, Alberta, Canada. Geology 25, 195-198. McAvoy, J.M., and McAvoy, L.D. (1997). Archaeological investigations of site 44SX202, Cactus Hill, Sussex County, Virginia. Research report series No. 8. Commonwealth of Virginia Department of Historical Resources, Richmond.Pitulko, V., Nikolskiy, P., Basilyan, A. and Pavlova, E. (2013) Chapter 2 Human habitation in Arctic western Beringia prior to the LGM.In K.E. Graf, C.V. Ketron and M.R. Waters (eds.) Paleoamerican odyssey, Center for the First Americans, College Station, p. 13-34.
In K.E. Graf,
Glenwood Erratic, one of the Foothills Erratics Train two 36Cl ages: 17 600+/-4 500 14 200+/- 4300
Arctic Ocean
Pacific Ocean
Generalized Cordilleran Ice Sheet,last glacial maximum
Laurentide Ice Sheet,
(ca. 11 000 years BP)
Arctic Ocean
Pacific Ocean
Atlantic Ocean
Arctic Ocean
Pacific Ocean
Speculative ice-capspredating fullbodied Cordilleran Ice Sheet
SpeculativeLaurentide Ice Sheet,
(ca. 25 000 years BP)
Arctic Ocean
Pacific Ocean
Atlantic Ocean
ICE- FREE C
ORRID
OR
ICE- FREE C
ORRID
OR
C
Rocky M
tns.
Mackenzi e Mtn
s.M
ac
kenzie v
al ley
Cana
dia
n Shield
200 km
Edmonton
CalgaryV
C
S
NW 49
49
49
120
O
O
O
O
O
Folsom
Folsom
Clovis
Clovis
S
Foothills erratics train
Origin of Foothills erratics train(Jasper National Park)
City
Archeological site
Generalized maximum limit of Laurentide Ice Sheet,last glacial maximum
Hudson Bay/Mississippi R.drainage divide
AB
B
Oldman
a. S sk. R.S
R.
Limit of glaciation
ALBERTA
CANADA
CANADA
USA
USA
MONTANA
BRITISHCOLUMBIA
Rocky Mtns.
Rocky M
ountains
NORTHWESTTERRITORIES
SA
SK
AT
CH
EW
AN
SA
SK
AT
CH
EW
AN
Watino
RD-S
Edmonton
Medicine Hat
o49 N
o49 No60 N
o120 W o110 W
o110 W
o114 W
o114 W
o108 W
o47 N
Wellsch Valley
Wellsch Valley
Lethbridge
Medicine Hat
Taber
Lethbridge
Hand Hills
CANADA
United States of America
o49 N
Hudson Bay
ArcticOcean
PacificOcean Atlanitic
Ocean
PacificOcean
Ungava
KeewatinMackenzie& Richardson mtns.
Smoking Hills
Gulf ofMexico
Glacial Lake Musselshell
Previously thought to be Illinoian (OIS stage 6 orolder: Fullerton et al. 2004))now known to be LateWisconsinan (OIS 2)
General area of Albertainferred to have been covered by the penultimate (Illinoian) ice sheet (westernlimit inferred).
Areas or locations with evidence of multiple glaciation
Areas dating glacialerratics to the LGM
Sites with evidence of a single (LGM) glaciation
? ? ? ?
? ?
Southern limit of glaciation
BrocketDel Bonita
Figure 3. Architectureof the Quaternary lithostratigraphy in central and northeast Alberta highlighting formations associated with multiple glaciations and illustrating the distribution of time-transgressive preglacial deposits oft he Empress Formation
in buried valleys. (GSC69-4)
Clay
SiltSand
Gravel
Diam
icton
Bedrock
Fl (10 m)
30 m
40 m
1 2 3 4 5 6 6A
45 m
50 m
55 m
60 m
Dmm(s)
Gm(i)
Gm
Gm
Sm
Sp(d)
Sp/Ds
Fm
Gms/Gm(i)Sm/Sp(d)
Dmm
Dms
Dmm
Dmm
Dmm
Dmm
Fm/Sm
Gm
Gm/Sm
Gm
Sm
Sm
Flv(d) (5m)Flv(d)
Flv(d)(s)
Flv
Flv
Fm (Holocene)
Fm (loess?)
Flv
R
R
R
Dmm(s)
Smp
S(f)/Gm(p)
S(s)
F/G(s)
Fl(d)(s)
Fl/Sh
Sm (Holocene soil)
S(s)
>37,000 y>34,000 y
37,000
Em
pre
ss G
rou
p
120 m
bedrock
Formation A
FormationB
FormationC
Selfpotential(mV) Resistance
upper
lower
>37,000 y >49,000 y >32,000 y
24,490+/- 20025,000+/-800 28,630+/-800
Sc
Sc?
Dms
Dms
Dmm(o)Gm
Sxl
Fl
Sl/Fl
Fl(d)
Dmm
Dmm
Dmm
Dmm
Dmm
Dmm
Dmm
Fl
Gm
GfuGfu
Sm (12 m)
Dmm (10 m)
Ds(s)
Fl/Dl
Fl
40 m
Fl(d)
Fl(d)Fm/Holocene soil
Montane glacialoutwash(Late Wisc.)
Montanetill (Late Wisc.)
Late Wisc.
LGM
Late Wisc.
Mid
dle
Wisco
nsin
an
Middle
Wisconsinan
LGM
Pen
ultim
ate
gla
cia
tion
Penultim
ate g
lacia
tion
Late Wisc.
Late
Wis
c.
Mo
nta
ne g
lacia
l ou
twash
(L. W
isc.)
Allo
cth
on
ou
s p
re-L
GM
bed
rock, g
lacia
l an
d n
on
gla
cia
l sed
imen
tsP
ost L
GM
gla
cio
lacu
strin
e a
nd
Ho
locen
e s
ed
imen
ts
Po
st
gla
cio
lacu
strin
e
an
d H
olo
cen
e
sed
imen
ts
Late
Wis
c. m
ax.
Oldman
Sas. k. R.
S
R.
CANADA
ALBERTA
USA
Rocky M
tns.
Saskatc
hew
an
Britis
h C
olu
mbia
o49 No110 Wo114 W
Medicine Hat
Taber
Lethbridge
Brocket
1
23
4
5 6,6A
Diamicton (contains Canadian Shield stones)
Diamicton (no Canadian Shield stones)
Sand
Silt and clay
LEGEND
Dropstone in silt and clay
Allochthonous bedrock block
In situ bedrock
Glaciogenic-sheared contact or zone
Radiocarbon age (years before present)
Erosional contact
Gradational contact
Conformable contact
Nature of contact uncertain?
Large intraclast in till
Roll-up structure in large intraclast
Gravel
?
?
Sources of sections: 1, 2--Jackson et al. 2009, sections O11, St3); 3--Jackson unpublished; 4--Stalker, 1962 (Kipp Section) and Jackson unpublished; 5--Stalker, 1962 (Taber section: plot by Jackson); 6--Proudfoot, 1985 (DNP-79-19: plot by Jackson); 6A--Stalker and Wyder, 1983
Pre OIS 2
OIS 1& 2 (includes allocthons of pre OIS 2 glacial sediments)
Pre OIS 2 glacialand non glacial sediments
Figure 4. Western limits of pre-OIS 2 glacial ice and stratigraphy along the Oldman River( from Jackson et al. 2011).
CALGARY
Lethbridge
Banff
Red Deer
Jasper
EDMONTON
Bow
River
Red D
eer r e Riv
htro
N
tcha ewk as naS
iverR
iverR
acsabahtA
114º W
49º 110º
52º
60º 60º
52º
B R
I T
I S
H C
O L
U M
B I A
S A
S
K
A T
C
H
E
W
A N
U.S.A.
Generalized distribution,
Foothills Erratics Train
Del Bonita
upland area
Paleo-glacier flowlines,
southern and central
Alberta: montane,
Laurentide ice sheet
(after Shaw et al., 2010)
ALBERTA
Pre LIS glacial limit
Figure 5. (A) Approximate areacovered by the penultimateLIS; area formerly mappedas Illinoian (OIS 6 or earlier) and location of siteswith 14C-dated stratigraphyshowing limits of pre-LGMglaciation(s)
ABSTRACTThere is extensive and robust stratigraphic and geomorphic evidence of progressive enlargement of North American (NA) continental ice sheets in a westerly direction during the glaciations of Quaternary Period. This culminated with a one-time coalescence of the Laurentide Ice sheet and valley glaciers from the Rocky and Mackenzie mountains and outlet glaciers from the Cordilleran Ice Sheet during marine isotope stage (MIS) 2. This singular coast-to-coast ice (CCI) event ended the pattern of broad ice-free corridors between Cordilleran and continental glaciers that was the norm during all previous Quaternary glacial maxima in North America. Recent discoveries of human settlements above the Arctic Circle in eastern Siberia during MIS 3 (~30 C14 ky BP) and an accumulation of archaeological sites in NA south of the limit of glaciation dating to MIS 3 (specifically <30 C14 ky BP to ~22 C14 ky BP) or contemporaneous with the CCI event during MIS 2 (specifically ~22 C14 ky BP to ~14 C14 ky BP) suggest that the limiting event for initial overland human migration into the Americas was the closing of the ice-free corridor rather than its opening as has been the orthodoxy.
** ** **** **
****
**
** ** ** **
****
**
**
**
EmpressFormationUnit1:time-transgressivepreglacialsandandgravel
Bedrock:undifferentiatedlithology
BonnyvilleFormation:diamict,minorstratifiedsediment
EthelLakeFormation:stratifiedsediment;clay,silt,sand,gravel
MarieCreekFormation:diamict,minorstratifiedsediment
SandRiverFormation:stratifiedsediment;dominantlysand
GrandCentreFormation:diamict,minorstratifiedsediment
GlacialLakeEdmontonsediments:sand,silt,clay
** -buriedoxidizedprofile
** -buriedoxidizedprofile
StratigraphicUnits
EmpressFormationUnit2:clayandsilt
BronsonLakeFormation:diamictandclay
MurielLakeFormation:stratifiedsediment;clay,silt,sand,gravel
EmpressFormationUnit3:glacialsandandgravel
%carbonateclasts,1-2mmsandfraction
%matrixcarbonate,silt-clayfraction
**
BuriedHelenaValley
BuriedWhitfordValley
BuriedBeverlyValley
No
rth
Sa
ska
tch
ew
an
Riv
er
BuriedBeverlyValley
BuriedStonyValleyS
turg
eo
nR
ive
rBuried
OnowayValley
No
rth
Sa
ska
tch
ew
an
Riv
er
Sa
nd
Riv
er
Be
ave
rRiv
er
40
06
00
80
01
00
0
0 200 km 400 km 600 kmSectionDistance
Str
atig
rap
hy
AG
SB
or
eh
ole
Lit
ho
log
AG
SB
or
eh
ole
Lit
ho
log
AG
SB
or
eh
ole
Lit
ho
log
AG
SB
or
eh
ole
Lit
ho
log
AG
SB
or
eh
ole
Lit
ho
log
AG
S-6
4
AG
S-S
RT-2
0
AG
S-S
RT-5
6
AG
S-R
79
-ED
16
AG
S-R
78
-ED
15
AG
S-R
77
-SR
36
AG
S-R
79
-ED
19
AG
S-R
79
-ED
9
AG
S-R
80
-ED
35
AG
S-R
79
-ED
17
AG
S-S
RT-2
2
AG
S-R
77
-SR
6
AG
S-S
RT-4
3
AG
S-R
78
-ED
10
AG
S-R
77
-SR
27
AG
S-R
78
-ED
11
AG
S-R
81
-ED
1
AG
S-R
77
-SR
12
AG
S-R
80
-ED
24
AG
S-R
77
-SR
35
AG
S-S
RT-4
4
AG
S-R
77
-SR
31
AG
S-W
AB
-01
AG
S-R
77
-SR
9
AG
S-S
RT-5
4
AG
S-W
EP
A9
9-1
AG
S-R
77
-SR
17
AG
S-W
EP
A9
9-2
AG
S-R
79
-ED
18
AG
S-R
77
-SR
34
AG
S-S
RT-1
2
AG
S-R
77
-SR
26
AG
S-R
77
-SR
29
AG
S-S
RT-1
1
AG
S-R
78
-ED
19
AG
S-S
RT-4
9
AG
S-R
80
-ED
36
AG
S-S
RT-5
3
AG
S-R
81
-ED
3
AG
S-R
79
-ED
2
AG
S-S
RT-7
AG
S-R
77
-SR
11
AG
S-R
79
-ED
8
AG
S-R
1
AG
S-R
77
-SR
7
AG
S-R
77
-SR
3
AG
S-C
L9
2-1
AG
S-1
6
AG
S-R
78
-ED
20
C14 agedatesofgrass
AG
S-R
81-E
D1
AG
S-R
81-E
D3
%S
an
d%
Ca
rbo
na
tes
%S
an
d%
Ca
rbo
na
tes
%S
an
d%
Ca
rbo
na
tes
AG
S-R
79-E
D17
>25,550yrB.P.
26,000±1100yrB.P.
MarieCreekFm.
GrandCentreFm.
BonnyvilleFm.
ref.D.Jennings,1984ConsolidatedConcretePits#46,#47C14 agedates
27,730±1060yrB.P. CaribouAntler31,520± 450yrB.P. CervidAntler39,960±3950yrB.P.MammothTusk35,500±2530yrB.P.Wood35,760±2130yrB.P.Wood>39,690 Wood41,110±3570yrB.P.Wood41,400±3990yrB.P.Wood42,910±3940yrB.P.Wood
ref.Young,etal.1994
A A’Southwest Northeast
110011201140
540
550
560
MoostoosUplands
CookingLakeMoraine
ColdLake
Edmonton
LacLaBiche
N.SaskatchewanR.
Athab
asca
R.
Verticalexaggeration~750
Pre OIS 2(sediments from twoor more ice sheets)
OIS 2
Ele
vatio
nm
asl
Magneticallyreversed till
36 Cl ages erratics on moraine surrounding Del Bonita
Sample Zero erosion 1.1 mm/kyr 3.3 mm/kyr Age ± Age ± Age ±
JJO01419 15500 630 14800 580 13840 510JJO01420 14040 510 13430 460 12530 410JJO01421 19600 780 18240 680 16550 580JJO01423 11500 420 10990 380 10250 340JJO01425 22100 800 20600 700 18700 600JJO01429 21050 670 19660 590 18100 520JJO01433 20800 780 20750 770 20800 780JJO01435 30300 1160 28350 1030 26300 930
COAST-TO-COAST ICE WAS UNIQUE TO THE LAST GLACIAL MAXIMUM. THE EVIDENCE IS SUMMARIZED IN FIGS. 2-5. PRIOR
TO THE LGM, ICE-FREE CORRIDORS BETWEEN THE CORDILLERAN GLACIERS AND CANADIAN SHIELD CENTERED
ICE SHEETS WERE THE NORM.
PART 3--A PRE-LGM ICE-FREE CORRIDOR A VIABLE OPTION FOR OVERLAND ENTRY INTO THE AMERICAS
The Paleoamerican Odyssey conference in Santa Fe, New Mexico in October, 2013 marked the passing of the Clovis-first paradigm. At present, there is a consensus that we really don’t know when and how people arrived in the Americas. What we do know is that people were present in the Americas when what is now Canada and the adjacent parts of the USA were covered by coast-to-coast glacial ice. Some controversial sites suggest the presence of humans prior to the closing of the last ice-free corridor. The duration of this glacial cover was short: between ca. 22 and ca. 14 ky. This was the culmination of westward expansion of ice sheets during the late Neogene glaciations (Barendregt and Duk-Rodkin, 2004). Subsequent work has shown that the western margins of continental ice sheets first reached Saskatchewan and eastern Alberta during a glaciation(s) prior to the last magnetic reversal (~0.78 Ma) (Barendregt et al. 2012; Barendregt and Enkin, 2012; Barendregt et al in press). What is notable is that throughout the Pleistocene, there was always unglaciated land connecting the Arctic with the interior of North America.
PART 1-- INTRODUCTION
PART 2. EVIDENCE FOR ONE COAST-TO-COAST GLACIATION
PaisleyCave14-15 ka
Monte Verdesite 14.8-14.2 ka
Monte Verde, MV >33 kaI
CactusHil ca. 18-20 ka
Meadowcroft 16 ka+
8 sites datingto LGM or mid-Wisconsin(Holen and Holen,2013)
ICE
-F
RE
EC
OR
RID
OR
Figure 1 Post LGMice-free corridorand location of Foothills erraticstrain
Figure 6. A speculative distribution of open land and glacial ice ca. 25 ka BP. Ice-free corridors open for habitation and entry into the Americas are indicated. Sites with yellow dots indicate approximate synchroneity with the opening of the post LGM ice-free corridor. Those indicated byred indicate synchroneity with coast-to-coast glacial cover or pre- LGM ice-free corridors (afterJackson and Duk-Rodkin, 1996).
(from Jackson et al. 2011).
-