Timing and extent of

Vashon ice east of the

Olympic Mountains

Porter and Swanson

(1998)

• Moderately fast advance (Seattle at 17.6 ka)

• Maximum (Tenino) at ~16.9-16.7 ka

• Moderately fast retreat (16.6 ka)

• Seattle ice-covered for ~1000 yrs

Ice sheet present

12,000

13,00014,000

15,00016,00017,000

18,00019,000

20,000

km south of UW

Ralph Haugerud (2012 talk, Centralia College)wood

peatlake sedimentsshells

Probabilistic ages (OxCal 4.1) reflect uncertainties in initial atmospheric 14C, marine reservoir correction, & 14C analyses

• Similar advance (Seattle 17.6 ka)

• Maximum (Tenino) ~600 yr later, at ~16.2 ka

• For Seattle, he inferred a longer glaciation (~1500 yr), but

• Faster retreat (Seattle ~16.1 ka)

Puget Lowland under ice.

(Blue lines are a model of subglacial drainage.) Image from Ralph Haugerud.

Puget Lowland

radiocarbon dates that bracket

Vashon stade• = 12,000-15,000 14C

yr BP radiocarbon.• =15-24 ka

luminescence.• Blue lines mark

latitude and longitude at UW-Seattle.

• Haugerud, and Porter and Swanson, did not have Hood Canal area data.

Selected data on

Vashon ice timing• Blue dots,

advance.• Yellow dots,

recession.• Dates in ka.• Blue lines mark

latitude and longitude at UW-Seattle.

Carpenter Lake

Hood Canal area data on Vashon ice timing• Later

advance.• Very short

maximum (Tenino) between ~16.2 and 15 ka.

• Simultaneous retreat (Tenino to northern Kitsap—timing enigmatic).

Along Hood Canal, the Vashon stade ice

came late

and left

fast (&

late?)