Basic Geological Concepts Uniformitarianism and catastrophism what are

Basic Geological Concepts • Uniformitarianism and catastrophism: what are they? • Establishing Geologic time - how? Suggestions? Cinzia Cervato, Dept. Geol & Atmos Sciences © 2001 1

The Huttonian Revolution • James Hutton and the Uniformitarianism • Geologic time: relative and absolute • The Earth’s interior Cinzia Cervato, Dept. Geol & Atmos Sciences © 2001 2

Geologic time Event Years ago Origin of the earth 4, 500 my Oldest dated rocks 3, 940 my Earliest life forms 3, 200 my Ocean and atmosphere “normal” 1, 000 my Primitive “higher’ animals 800 my Beginning of the Phanerozoic 570 my First land plants 400 my Single supercontinent 250 my Death of the dinosaurs 65 my Human beings appear 4 my End of last ice age 13, 000 yr Birth of Christ 2, 000 yr Calendar date 1 Jan. , 00: 00 hrs 10 Feb. 16 April 1 Oct. 1 Nov. 12 Nov. 28 Nov. 10 Dec. 26 Dec. 31 Dec. , 18: 00 hrs 31 Dec. , 23: 56 hrs 20 sec 31 Dec. , 23: 59 hrs 46 sec Cinzia Cervato, Dept. Geol & Atmos Sciences © 2001 3

Hydrologic cycle Cinzia Cervato, Dept. Geol & Atmos Sciences © 2001 4

Rock cycle Cinzia Cervato, Dept. Geol & Atmos Sciences © 2001 5

Plate tectonics • What is it? • What kind of evidence would you look for to prove that continents were once united into one megacontinent? Cinzia Cervato, Dept. Geol & Atmos Sciences © 2001 6

Continental Drift • Alfred Wegener • Physical evidence – Matching coastlines – Structural evidence – Distribution of ancient glaciers and life forms – Similarities of the sedimentary record Cinzia Cervato, Dept. Geol & Atmos Sciences © 2001 7

Continental Drift • Paleomagnetic evidence • Continental drift and Plate tectonics Cinzia Cervato, Dept. Geol & Atmos Sciences © 2001 8

Summary • • ‘The present is the key to the past’ Concept of geologic time Rock and hydrologic cycles Fundaments of plate tectonics Cinzia Cervato, Dept. Geol & Atmos Sciences © 2001 9