_Obs._--This group includes the _Lower Bunter_, _Zechstein_, and _Rothliegendes_[21] of the German geologists. The _Permian_ comprises all the deposits that intervene between the Triassic above, and the Carboniferous below; and it is believed that this formation contains but one type of animal and vegetable life. [21] Signifying _Red-dead-layer_; it is a German mining term denoting that the copper of the upper bed has died out; this layer not being metalliferous. The Carboniferous, or Coal Formation. (_Wond._ pp. 660-748). Sandstones, grits, shales, layers of ironstone, and clay, with immense beds of coal; fresh-water limestones sparingly; marine limestones abundantly. _Subdivisions_:-- 1. _The Coal Measures._--Sandstones, shales, and grits, with numerous beds and seams of Coal; ironstone nodules. Land plants in profusion. Intercalations of bands of limestone with fresh-water bivalves and crustaceans in some districts; and with marine shells in others. 2. _Millstone Grit._--Sandstones, shales, and quartzose conglomerates and grit, (_provincially_, Millstone-grit): with shales and thin seams of coal, and plants of the coal-measures in some localities. The conglomerates and grits have evidently resulted from the destruction of granitic rocks. 3. _Carboniferous_, or _Mountain Limestone_.--A series, nearly 1,000 feet in thickness, of limestones and flagstones, abounding in crinoideans, corals, and marine shells and crustaceans; with layers and nodules of chert. Ores of lead, zinc, copper, barytes; fluor spar, &c. Limestones, with innumerable shells of the genera Productus, Spirifer, Goniatites, Orthocera, Bellerophon, &c. Several varieties of black, bluish grey, and variegated marbles. Coal occurs in the mountain limestone of some parts of Russia. _Obs._--The strata comprised in the carboniferous (coal-hearing) system, consist of sandstones more or less felspathic, and of dark bituminous shales with innumerable ferns, and other vascular cryptogamiæ, and coniferæ, &c. The uppermost group is composed of numerous alternations of coal, clay, shale, ironstone, and sandstone; the middle, of sandstones, shales, clays, and quartzose conglomerates, generally of a dull red colour; and the lowermost, of crystalline limestones with occasional layers of chert, abounding in marine shells, corals, crinoidea, and other exuviæ. These lower limestones are the principal repositories of the lead ores of Derbyshire.