Catastrophes and Lesser Calamities The causes of mass extinctions

In Catastrophes and Lesser Calamities, renowned geologist Tony Hallam takes us on a tour of the Earth's history, and of the cataclysmic events, as well as the more gradual extinctions, that have punctuated life on Earth throughout the past 500 million years.
While comparable books in this field of study tend to promote only one likely cause of mass extinctions, such as extraterrestrial impact, volcanism, and or climatic cooling, Catastrophes and Lesser Calamities breaks new ground, as the first book to attempt an objective coverage of all likely
causes, including sea-level and climatic changes, oxygen deficiency in the oceans, volcanic activity, and extraterrestrial impact.
Hallam focuses on the so-called 'big five' mass extinctions, at the end of the Ordovician, Permian, Triassic, and Cretaceous periods, and the later Devonian, and he also includes less well-known examples where relevant. He devotes attention especially to the attempts by geologists to distinguish
true catastrophes from more gradual extinction events, and he concludes with a discussion of the evolutionary significance of mass extinctions, and on the influence of Homo sapiens in causing extinctions within the last few thousand years, both on land and in the seas.

This is a book about the dramatic periods in the Earth's history called mass extinctions - short periods (by geological standards) when life nearly died out on Earth. The most famous is the mass extinction that happened about 65 million years ago, and that caused the death of the dinosaurs. But that was not the worst mass extinction: that honour goes to the extinction at the end of the Permian Period, about 250 million years ago, when over 90% of life is thought to have become extinct. What caused these catastrophes? Was it the effects of a massive meteorite impact? There is evidence for such an impact about 65 million years ago. Or was it a period of massive volcanic activity? There is evidence in the rocks of huge lava flows at periods that match several of the mass extinctions. Was it something to do with climate change and sea level? Or was it a combination of some or all of these? The question has been haunting geologists for a number of years, and it forms one of the most exciting areas of research in geology today. In this book, Tony Hallam, a distinguished geologist and writer, looks at all the different theories and also what the study of mass extinctions might tell us about the future. If climate change is a key factor, we may well, as some scientists have suggested, be in a period of mass extinction of our own making.

1 - In search of possible causes of mass extinctions
2 - Historical background
3 - Evidence for catastrophic organic changes in the geological record
4 - Impact by comets and asteroids
5 - Sea-level changes
6 - Oxygen deficiency in the oceans
7 - Climate change
8 - Volcanic activity
9 - Pulling the strands together
10 - The evolutionary significance of mass extinctions
11 - The influence of humans
1 - In search of possible causes of mass extinctions
2 - Historical background
3 - Evidence for catastrophic organic changes in the geological record
4 - Impact by comets and asteroids
5 - Sea-level changes
6 - Oxygen deficiency in the oceans
7 - Climate change
8 - Volcanic activity
9 - Pulling the strands together
10 - The evolutionary significance of mass extinctions
11 - The influence of humans

Tony Hallam is Emeritus Professor of Geology at the University of Birmingham and the author of several books on geology.