MIOCENE (Gr, less recent), a term introduced by Lyell to characterize the middle tertiary strata,which he supposes to contain a smaller proportion of recent species of mol luscs than the newer Pliocene. and more than the older eocene. He estimates time pro portion of living to fcipssid,w0ties in the miocene at 25 per cent, • Strata of this ago occur in Britain in two limifed and far separated localities—in the Island of Mull, and at Dartmoor in the s.e. of England. In this last district, they exist at Bovey Tracey, in a flat area of 10 in. long by 2 in. broad, and consist of clay interstratified with beds of imperfect lignites. Pengelly and Beer have recently examined the strata of this small basin, and have found that all the plants are of miocene age, and belong to the some species as those found in similar deposits, not only on the continent, but in Iceland, Greenland, and Arctic America. Theirflicies indicates a warmer climate than the pres ent, and the geographical range of the species is unexampled in the existing flora. The Mull beds are situated at the headland of Ardtun, and consist of interstratificd basalts, ashes, and lignites. There are three leaf-beds, varying in thickness from 1 to 21- ft.,
separated by two beds of ash, the whole resting on and covered by strata of basalt. The whole thickness is 131 feet. It is suppo3ed that the leaf-beds were deposited in it shallow lake or marsh, in the vicinity of an active volcano. One of the beds consists of a mass of compressed leaves without stems, and accompanied with abundant remains of an equisctum, which grew in the marsh into which the leaves were blown. The leaves belong to dicotyledons and coniferre, and arc of species similar to those of Bovey Tracey.
The Fahlims of France are of this age, as are also part of the Mollassi of Switzer land, and the Mayence and Vienna basins. . Of, the same period are the highly fossilif erous deposits in the Sewalik hills, India, containing the remains of several elephants, a mammoth, hippopotamus, giraffe, and large ostrich, besides several carnivora, monkeys, and crocodiles, and a large tortoise, whose shell measured 20 ft. across, The European beds contain the remains of the dinotherium (q.v.).