GEOG 2OC3 Lecture Notes - Lecture 1: Cordilleran Ice Sheet, Axial Tilt, 40Th Parallel North
Document Summary
This was a recent glacial episode in the northern hemisphere. Marks the beginning of the quaternary period. The ice sheets extended south to 40 degrees latitude around nyc (in usa) Home sapiens: evolve into modern forms, migrated around the world. 3 km thick glaciers covered canada and europe. Earth orbits the sun on an elypse. Gravity pulls the sun and moon on the equator (changes this shape: orbital eccentricity, axial precession, axial tilt. All of these contribute to the solar insulation the earth gets and influences 26,000 year cycle of glaciers: orbital eccentricity. Departure of the earths elliptical orbit from a circular shape. Earth doesn t or(cid:271)it the sun in a perfe(cid:272)t (cid:272)ir(cid:272)le. Oblong shape (more resembles how the earth orbits: axial precession. The slow and continuous change in the orientation of the earths rotational axis. Caused by gravitational pull on earth by the moon and the sun. Full circle happens every 25,000 years: axial tilt.