Natural History - Natural Agate Cut and Polished Geode Half Group [6]

Comprising three Knightia alta specimens, each on a round matrix. 140 grams total, 74-82 mm



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.

Comprising three matrices, each containing Promicroceras planicosta fossil ammonites. 341 grams total, 4.8-12 cm



From Charmouth, UK. Ex Lincolnshire, UK, collection.

Three wind-rounded pebbles each in a hollowed out 'nest'; with a hessian draw-ribbon pouch. 328 grams total, 54-58 mm



From the Kalahari Desert, Southern Africa. Ex Mineral Imports, London, UK. Gregory, Bottley & Lloyd (Gregory's).