Natural History - Polished Fossil Goniatite Display

Knightia alta specimen on a rectangular matrix. 397 grams, 13.3 cm



From Wyoming (Green River Formation), USA. From a Lincolnshire, UK, collection.

In southwest Wyoming (and parts of Colorado and Utah) in the Green River Formation are found some of the world's most outstanding specimens of fossil fish. The Green River system was composed of three lakes: Lake Ulinta, Lake Gosiute and Fossil Lake. These Eocene lakes lay in a series of intermountain basins formed by geological events that uplifted the Rocky Mountains during the early Tertiary time. The climate was much different from the desert-like climate of this area today. Both the fauna (crocodiles, alligators, boa constrictors and some subtropical fish families) and the flora (such as large palm trees) indicate a climate much like that found along the Gulf Coast today. Large amounts of ash found in the sediments indicate that volcanoes were particularly active at this time.

In enhanced dyed pink colour, opened to reveal the internal crystal filled cavity. 119 grams total, 55-56 mm



From a Cambridgeshire, UK, collection.

The matrix showing pale sky-blue opal, collection number 425, with an old James Walker label. 34.8 grams, 39 mm



Acquired on the UK mineral and fossil market, since 1970. From the historic mineral collection of Richard Valentine Cain, London, UK, thence by descent. Accompanied by an original historic index file card.