DATING THE GLACIATION OF SOUTHERN PART OF NORTH CASCADE RANGE by: James Leask.
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Transcript of DATING THE GLACIATION OF SOUTHERN PART OF NORTH CASCADE RANGE by: James Leask.
DATING THE GLACIATION OF
SOUTHERN PART OF NORTH CASCADE
RANGE
by: James Leask
Main Drift Sheets
• Lakedale (youngest; 11,050-16,000 years ago)– Hyak– Domerie– Ronald– Bullfrog
• Kittitas (intermediate; over 120,000 years ago)– Indian John– Swauk Prairie
• Thorp (oldest; over 700,000 years ago)
Dating Criteria
• Upper limit of erratics• Moraine size/position• Outwash terrace position• Estimated glacial limit position• Thickness of weathering rinds• Soil Profile
Soil Measurements
• % Clay • Silt to Clay ratio• pH Levels• % Magnetic Minerals• Moist Color
Thermoluminescence Dating
Procedure1.Once buried, rock accumulates energy at the
atomic level.2.Rock samples are taken to lab and exposed to
various doses of radiation.3.Photons emitted are recorded.
Intro to OSL
OSL – Optically stimulated luminescense
According to Berger, OSL has the potential to produce more accurate dates than TL.