BAGSHOT BEDS, the lowest series of.strata in the middle eocene formation of Britain. The name is derived from Bagshot heath in Surrey, where they were first examined; but, as they are more fully developed and better seen in the isle of Wight, time rocks there are now considered the typical representatives of the series. Ile strata are arranged into four groups: 1. The Upper B. B.; composed of yellow and white sands with ferruginous stains, generally unfossiliferous, though a remarkable exception exists at Whitecliff bay, Isle of 'Wight, where a bed contains a large number of very friable shells. 2. The Barton beds, consisting of colored clays interstratified with sand and loam. They are rich in fossils, chiefly the shells of mollusca, but contain also the remains of a fish and several reptiles. Here, too, the nummulite (q.v.), so characteristic of the tertiary formations, makes its first appearance in a descending order. This genus dies out with the nummulites variolaris, the small species found in these beds. 3. The Brad:16.91mm beds, so called from their extensive development at Bracklesham bay, near Chichester in Sussex, are composed of rnarly clays and white sands, capped by a bed of flint-pebble conglomerate, and resting on dark carbonaceous clays. This is the most
highly fossiliferous group in the series. Two species of plants have been noticed. The remains of G reptiles and 21 fishes have been described, besides a long list of mollusca, amongst which is the magnificent cerithium (q.v.) gigeenteum, so in the ealcaire grossier of Paris, where it is sometimes 2 ft. in length. The prevalence of genera now only known as inhabitants of tropical or Sub-tropical seas, such as volutes and cowries, together with their companion lunulites and corals, makes it highly probable that a warm climate prevailed during the deposition of these 'strata. 4. The Lower B. B., consisting of alternations of variously colored sands with gray, chocolate-colored, or white pipe-clays. The white clays contains the only fossil organisms found in this group—beautifully preserved leaves spread out in the layers of the clay.
The series rests on the true London clay. Its maximum thickness is about 1200 feet.