Paleogene silcretes and the 55 Ma global warming event: is there proof in the Hertfordshire Puddingstone?

Abstract

Does the fabled Hertfordshire Puddingstone, formed at the northern edge of the Paleogene Anglo-Paris Basin, underline the geological case for concern about human-induced climate change? Recent studies at Colliers End, near Hertford, indicate that a late Paleocene pebble bed of rounded flints was cemented by silica before deposition of overlying early Eocene mudstones. Silicification appears to have taken place beneath a land surface exposed to intense weathering at the Paleocene-Eocene Thermal Maximum (PETM). One of a number of subsequent global warming events (Eocene hyperthermals) may have silicified fossiliferous pebble beds in northern France which were deposited in the early Eocene. The PETM is one of a number of global warming events in the geological record that show us the effects of sudden release of a thousand or more gigatonnes of carbon dioxide to the atmosphere. We are currently dumping carbon dioxide into the atmosphere at rates and volumes comparable to those recorded at the PETM, 55 million years ago (55Ma). As a result of our own actions, we may expect global warming, acidification of the oceans, a global rise in sea level and extinction of animals and plants. The political and social message from the PETM, and from similar events in the geological record, is that we should now take our finger off our very own carbon trigger.