Exam 1 Study Guide
Peopling of Europe:
Long vs short chronology
Long chronology proponents argue for people (Homo erectus or heidelbergensis) in Europe before 1 million years ago.
Short chronology proponents argue for colonization after 730,000 years ago. This corresponds to the Brunhes-Matuyama boundary, when the Earth’s magnetic poles switched from a Reversed to Normal polarity.
Sites such as Orce and Sima del Elefante in Spain are equivocal evidence for early human presence and have dating problems.
Pleistocene
Period of time 1.8 mya to 10,000 years ago
Characterized by the Ice Age
Actually there have been over 50 “ice ages
Ice ages
-latest began after 1.8 mya
-caused by Milankovitch cycles
-Eccentricity- 100,000 year cycle of Earth’s orbit around the sun; refers to the shape or degree of stretching of the orbit
-Obliquity- 41,000 yr cycle of the axial tilt or roll of the earth; today it’s 23.5 degrees; this impacts the degree of seasonality in climate; less tilt would mean warmer winters and cooler summers allowing for the growth of ice sheets
-Precession-23,000 yr cycle of the wobble of the Earth as it spins; this affects the position of the Earth at the winter and summer solstices; now the Earth is closest to the sun in winter; this is the only parameter in glacial mode
Oxygen Isotope Stages
-this refers to the sequence of the changing ratios of 18O to 16O in the shells of tiny marine organisms called foraminifera found in sediment layers at the bottom of the ocean
-the lighter isotope 16O evaporates and gets trapped in ice sheets during the glacial periods meaning that the oceans are enriched in 18O
-normally the balance would be maintained through rainfall and runoff by which 16O returns to the oceans
-deep-sea cores drilled through the sediment layers at the ocean bottom provide a continuous record for the last 2.5 million years of glacial-interglacial cycles
-over 50 stages