09.04.2013, 06:35
In my neighbourhood is a rock face that has geology dating from the Jurassic. It's been a while since I've been down there but yesterday I thought I would have a browse. You can see in the rocks the story of changing conditions. Fine sand and muddy silt lower down, the original sub tropical beach, where mollusc and bivalve shells are scattered. Higher up is the later warm shallow sea of the late Jurassic, where sometimes you find very impressive ammonite shells (those spiral knobbly shells housing squid like creatures so beloved of BBC animations), some up to a foot across. Higher up and out of reach are the Cretaceous period lagoons, a fascinating cocktail of fresh and saltwater wetlands that would have had a natural history presenter in a state of euphoria.
The trouble is the rocks are on a public path and fossil hunters regularly plunder them. As I expected, the dangerous undercut that previous digs had left were broken off and lying around in chunks. It's rare to catch a glimpse of something before it vanishes into the nearest car boot sale, but there it was, another ammonite, or more accurately the imprint of where it had been. That was a seriously large dino-squid as far as such shellfish go.
My thoughts wandered to how it would have been back then. Handfuls of dolphin-esque ichthyosaurs darting lazily here and there. Maybe a lone shark, sniffing around, competing with marine crocodiles or deciding to get the heck away from the larger marine predators that outsized some modern whales. Or in the deeper water, fish nearly 100 metres in length, calmly gulping in plankton by the hundred-weight.
It would have been warm back then. The climate was stable for a long time and with ten times as much carbon dioxide in the air as today, a period where big things prospered. Now it's rainy old Swindon. With thoughts back to the modern day, a chap walking his dog watches me suspiciously. Ahem. Well, back to the ranch...
The trouble is the rocks are on a public path and fossil hunters regularly plunder them. As I expected, the dangerous undercut that previous digs had left were broken off and lying around in chunks. It's rare to catch a glimpse of something before it vanishes into the nearest car boot sale, but there it was, another ammonite, or more accurately the imprint of where it had been. That was a seriously large dino-squid as far as such shellfish go.
My thoughts wandered to how it would have been back then. Handfuls of dolphin-esque ichthyosaurs darting lazily here and there. Maybe a lone shark, sniffing around, competing with marine crocodiles or deciding to get the heck away from the larger marine predators that outsized some modern whales. Or in the deeper water, fish nearly 100 metres in length, calmly gulping in plankton by the hundred-weight.
It would have been warm back then. The climate was stable for a long time and with ten times as much carbon dioxide in the air as today, a period where big things prospered. Now it's rainy old Swindon. With thoughts back to the modern day, a chap walking his dog watches me suspiciously. Ahem. Well, back to the ranch...
