Download Origins of the First Californians

Setting the Stage for the Peopling of the Americas
Origins of the First
Californians
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John R. Johnson
Anthropology 131CA
Three Stage Colonization Model
for the Peopling of the Americas
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2.
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4.
Divergence from ancestral
Asians abt. 40,000 years
ago.
Occupation of Beringia
between 30,000 to 16,000
years ago, population
isolated.
Expansion into the
Americas approximately
16,000 years ago.
Effective population size of
Proto-Amerinds estimated
at 6,000 to 10,000
individuals
Peopling of Siberia was episodic
between 35,000 and 15,000 years
ago.
Middle Upper Paleolithic, 33,000 to
24,000 BP, people pushed further
north.
Last Glacial Maximum (LGM),
24,000 to 21,000, people retreated
southward to refugia.
Different technologies, earliest
microblades in northern Japan (not at
Mal’ta)
Late Upper Paleolithic (post-LGM) –
high tool diversity, first evidence for
domestic dogs, medium to largebodied game are focus.
Mal’ta
The Siberian Connection
Questions regarding migration:
• What were the routes traveled?
• When was migration possible?
North American Late Pleistocene Fauna
ca. 14,000 yrs. BP
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How Bad Was It?
Clovis Points
• End Pleistocene ( ~13,000 ka) - the last
catastrophic faunal extinction in geologic past
• Coincides with the deglaciation between the
last glacial episode and the present Holocene
interglacial
• Timing of the extinctions are well constrained
between the end of last glacial episode and
the beginning of the ‘Younger Dryas’ (~1,500
yrs), following the Clovis human occupation
Theories for the Cause of this Extinction
• Human
Black Mat Distribution of early Younger Dryas Age
overhunting
- isotopic studies suggest a more diverse diet
- diverse hunting strategies needed to exterminate
such a wide variety of taxa
- specialization in big game hunting rare
- game rich landscapes with few people
- other taxa clearly exploited (e.g. bison) actually
survived the extinction
Santa Rosa Island
• Climate change
- Mammal extinction is coincident or close to abrupt ‘Younger Dryas’ cooling event
- Within the context of late Quaternary climate history abrupt cooling
not an uncommon event occurring frequently over last 80 kyrs
- Younger Dryas cooling event less severe compared to earlier events in the
Quaternary with no associated extinction event
• Combination - overhunting/climate change
Black Mats
(from Vance Haynes, 2005)
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Evidence for an Impact Event?
Black Mat above Clovis/Extinction layer
Titanium-rich Magnetic Spherules
Algal Mat
Top Clovis
~13,000 ka
extinction
ET debris
Glass-like Carbon
Murray Springs, AZ, photograph provided by A. West
Carbon Spherules
The Younger Dryas Boundary (YDB)
Cosmic Impact Hypothesis
Where is the Crater?
Daisy Cave
Firestone and West 2005
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Bathymetic Map of Gulf of St. Lawrence
Corossol Crater, Gulf of St. Lawrence
Articulated pygmy mammoth skeleton discovered in 1994
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Mouth of Arlington Canyon, Santa Rosa Island
Excavations by Phil Orr, 1960
Arlington Man’s bones in situ, 1960
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Locations of Dated C-14 Samples
Stratigraphic Location of Human Bone
C-14 Samples Collected in 2001
Sample No.
C-14 Age
(B.P.)
Approx.
Calendar
Years (B.P.)
Material/Provenience
Lab No.
AS-2001-150
Sediment above
"Black Band"
CAMS84540
9,985 ± 40
11,300
AS-2001-154
Sediment near top of
"Black Band"
CAMS84542
10,315 ± 40
12,200
AS-2001-155
Sediment near bottom of
"Black Band"
CAMS84541
10,725 ± 40
12,900
AS-2001-161
Charcoal immediately
above layer with human
bone
CAMS84543
11,250 ± 40
13,200
AS-2001-162
Charcoal beneath layer
with human bone
CAMS84544
11,580 ± 45
13,500
AS-2001-163
Charcoal from lowest
stratum sampled
CAMS84545
11,640 ± 40
13,800
GPR survey quadrants, June 2005
Datum
A
B
C
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Landscape reconstruction of the
Arlington Springs vicinity
based on GPR survey
Quadrant C
Quadrant B
Quadrant A
Scott Newhall and Doug Hechter with Scaled Sediment Core Poster
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Application of Sea Level Curve to the
Arlington Springs Sedimentary Record
Younger Dryas Black Layer
AMS 14C Dating of Late Pleistocene/Early
Holocene Sediments at Arlington Springs
“Pebble” Layer
“Triplet”
Younger Dryas
Black Layer
Just Beneath YDB
Arlington Man &
Rodent Bone Bed
Below Arlington
Man Layer
Johnson et al., 2007
16,000
15,000
14,000
13,000
12,000
11,000
Dated Layers from
Lower Strata in
Sediment Cores
Calendar Years Before Present (2 sd)
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Arlington Canyon (AC-003)
Arlington Canyon Late Pleistocene alluvium
(Cal BP 13,130 to 12,800)
Date from piece of pine wood (Yellow pine group)
Carbon Spheres
Magnetic Spheres & Disks
Courtesy of Douglas Kennett, UO
Images of Carbon and Metallic Spheres from
Arlington Canyon Late Pleistocene Alluvium
AC-003 Carbon Spherules
Nanodiamonds
TEM Image
Reticulate
Interior
Diamond Diffraction Pattern
Photos courtesy of Doug Kennett and Allen West
Courtesy of Douglas Kennett, UO
Summary - Arlington Springs
• The Channel Islands were connected as a single landmass in the late
Pleistocene, but were separated from the mainland.
• The stratigraphy on Santa Rosa Island is largely undisturbed by bioturbation
and other soil mixing processes.
• GPR aided in reconstructing the ground surface during the Younger Dryas
Period, because of the change in stratigraphy caused by the black layer.
• The YDB at Arlington Springs has been dated between 12,900 and 12,200 Cal
BP.
• Arlington Man’s skeletal remains were recovered from a period of alluvial fill
that dates to about 13,000 to 13,200 years ago, where some chert microflakes
have also been discovered.
• Initial attempts at sampling the YDB at Arlington Springs yielded very few
carbon spherules but some glass-like carbon.
• A second location (upcanyon) was discovered that dated to the beginning of
the Younger Dryas that yielded abundant carbon spherules and pollen
indicative of a pine-cypress forest that disappeared at the end of the
Pleistocene.
• Abundant evidence of an extinct species of Deer Mouse was present before
the Younger Dryas and disappeared along with the pine-cypress forest.
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