The first billion years on Earth and Mars: A geologist’s perspective – Clark M. Johnson

Despite the likelihood of early habitability on both Earth and Mars, the geologic evolution of these two planets, and the rock record they preserve, is quite different. Plate tectonics on Earth played a central role in evolution of our biosphere, and yet has destroyed much of the early Earth rock record, creating great challenges for finding evidence for early life on Earth. Mars did not have Earth-style plate tectonics, but the evidence is clear that Mars was habitable very early in its history. Preservation of the early Mars geologic record is excellent, raising the possibility that it might contain evidence for the earliest life in the Solar System...

(Re)Inventing the Flat Earth” – Peter Sobol

A survey of the history of ideas about the shape of the Earth in Western Civilization with a focus on the nineteenth century, which saw both the rise of the Warfare hypothesis (which encouraged secularists to misrepresent medieval ideas) and the rise of the modern Flat Earth movement, concluding with a glance at the present state of that movement.

About the Speaker:

Peter Sobol has taught the history of science at Indiana University, Oklahoma University and the University of Wisconsin-Madison. in addition to standard history of science he has taught courses on the history of pseudoscience and the occult, hence his abiding if morbid interest in the vagaries of human thought.