Quiz – 5 minutes: Separate Paper1. In which of the following would you most likely find

commercially usable reservoirs of oil or deposits of sand and gravel?A) Continental Shelf

B) Continental Slope C) Continental Rise

2. Which of the following sediments precipitates directly from seawater?A) TerrigenousB) BiogenousC) Hydrogenous

3. Compare and contrast the Pacific and Atlantic continental margins.

Puget Sound Seafloor

Chapter 14 vs. Puget Sound

• In general, the features described in Chapter 14 are not found in Puget Sound (no mid-ocean ridges, cont’l shelf, slope, rise, seamount, guyot, trench, atoll…)

• Instead, Puget Sound’s seafloor consists of sediments shaped by recent (<25,000 years before present) glacial action

Glaciers

Energy and Movement of Material

Water can provide a “low to high energy” environment and is capable of moving clay, sand, gravel and boulders

Air is generally “low energy” and is capable of moving clay and sand

Glaciers…

Glaciers can be “extreme energy” and move clay, sand, boulders, and house-sized boulders

Glacial “Erratic”

How Erratics Can be “Plucked” and Transported

Glacial Scouring

• Video• http://exhibits.pacsci.org/puget_sound/graphi

cs/ps_glaciationsm.mov

So, What’s Beneath the Surface?

Puget Sound “Scoured Out” by Glaciers

Red = ShallowBlue = Deep

Puget Sound “Scoured Out” by Glaciers

Red = ShallowBlue = Deep

Deep basins

Shallow Sills

Profile View of Previous SlideNorth South

Shallow Sills

Deep basins

Video Again

http://exhibits.pacsci.org/puget_sound/graphics/ps_glaciationsm.mov

Interesting Aside (Not Oceanography)

Glacial Deposits•Layered clay accumulates in the bottoms of large, pro-glacial (“in front of the glacier”) lakes

•Layered sand and gravel accumulates in the bottoms of rivers draining the lake (called “outwash”)

•“Glacial till” deposited directly by the glacier: very dense, non-layered mixture of clay to house-sized boulders

Glacial Deposits“Lacustrine” (lake) clay

Clay

Glacial Deposits

“Outwash” sand and gravel

Outwash

Glacial Till

Interesting Aside (not oceanography)

Summary of Puget Sound Glaciation

1.“Old,” pre-glacial sediments (hard sands, clays etc.) on bottom2.Pro-glacial lake deposited clay next3.Advancing glacier deposited “outwash” (sand and gravel) next4.Glacier deposited till next5.Glacier receded, scouring the landscape and depositing the opposite sequence6.Left behind Puget Sound, which filled with ocean water

Landslide Situations