Supercontinent - Pangea . (zoom in to view the names of the geologic eras) Alfred Wegner Supercontinent - Pangea . Pangea Gondwanaland Laurasia 1 Geologic Time Milankovitch Cycles (~ 100,000 years) Milankovitch Cycles (~ 100,000 years) Milutin Milankovitch (1879-1958) 2 Factors affecting Earth’s Climate 1. Milankovich Cycles (~100,000 years) 2. Pacific Decadal Oscillation (~10 – 15 years) 3. El Nino/La Nina Cycles (annual cycles*) Time Scale: The Cenozoic Era “Recent Life” • Pleistocene Epoch – Ice ages (WIKN) – Humans appear – 1.8 my to 10,000 yr http://www.museum.state.il.us/exhibits/ice_ages/images/loopglac.gif Continental Glaciers . Stages Wisconsin (most recent) What is a “nunatak”? Illinoian Kansan Nebraskan (oldest) 3 Human Migration National Genographic Project Human Migration Source: www.utexas.edu/features/2007/ancestry/ Continental Glaciers . Question: What type of vegetation covered the landscape immediately south of the continental glaciers? 4 Glaciers, Biotic Exchange, and Vegetation Patterns Vegetation Patterns during Glacial Periods North American Glaciers . Note the names and locations of the refugium 5 Glacial Lake Missoula Glacial Lake Missoula The name Missoula is derived from a Flathead (Salish) term meaning “cold, chilling waters”. Continental Glaciers . How did the continental glaciers affect the Willamette Valley? 6 Glacial Lake Missoula Glacial Lake Missoula A Sudden Onslaught of Water The Dalles, Oregon ~ 1,000 feet 7 Question.. Question: As the glaciers formed, they locked up water, how much lower were sea levels then? Astoria Trench Pacific Salmon Species Genus Oncorhynchus – “hooknose” Pink Salmon (O. gorbuscha) Steelhead Trout (O. mykiss) Chum Salmon (O. keta) Sea-run Cutthroat Trout (O. clarkii) Sockeye Salmon (O. nerka) Coho Salmon (O. kisutch) Chinook Salmon (O. tshawytscha) 8 Glacial Lake Missoula Glacial Erratics Lake Bonneville The lake was named after the early explorer, B.L. Bonneville. It was formed about 50,000 years ago and had receded to the current level of the Great Salt Lake by about 10,000 years ago. It was about 560 km (about 350 mi) long and 240 km (150 mi) wide, had a maximum depth of more than 305 m (1000 ft), and was more than 1525 m (5000 ft) above sea level. 9 Megafaunal Extinctions Megafaunal Extinctions Megafaunal Extinctions The stag-moose Shasta ground sloth (scientific name Cervalces scotti) Nothrotheriops shastensis 10 Megafaunal Extinctions Ancient Bison Dwarf Pronghorn Bison Antiquus Capromeryx minor Extinct Camel Camelops hesternus Megafaunal Extinctions Columbian Mammoth American Mastodon Mammuthus columbi Mammut americanum Megafaunal Extinctions Sabertoothed Cat Smilodon fatalis American Lion Panthera atrox 11 Megafaunal Extinctions Dire Wolf Canis dirus Short-faced Bear Arctodus simus The Misnamed Extinct “Irish Elk” ~ 4 meters Source: http://www.ucmp.berkeley.edu/mammal/artio/irishelk.html Holocene Ecology Anthropocene? 1. Vegetation Patterns 2. Ecological Communities 3. Species and Populations 12.