LECTURE

different from today’s Earth. How did its surface change to create the familiar geography that has done so much to shape human history? The next lecture will tackle this question by describing the fundamental geological paradigm of plate tectonics.

Essential Reading

Supplementary Reading

Questions to Consider

Chaisson, Epic of Evolution, chap. 4. Christian, Maps of Time, chap. 3.

Delsemme, Our Cosmic Origins, chap. 4. Macdougall, A Short History of Planet Earth.

1. How and when did the Earth acquire the layered structure it has today, with a metallic center, a semimolten mantle, a thin but rigid crust, and an atmosphere?

2. What have been the crucial stages in the history of the

Earth’s atmosphere?