3. Some of the principal members of this class are: 1. Argillaceous, and sandy depositions from the sea. 2. Marl, and gypsum, from fresh water. 3. Sand, and sandstone, with or without shells, from sea water. 4. Limestone, and silicious millstone grit, from fresh water. _Conclusion._ From what has been said above we may clearly deduce the following particulars. 1. The crust of the earth is constructed of four great general classes of rocks: the _primitive_ at the foundation; the _transition_, laying immediately over the primitive; the _secondary_ immediately above these; and the _tertiary_ at the surface. In this arrangement we consider the rocks in their natural position. 2. The _position_, _structure_, and _organic remains_ of these classes, clearly point out a grand geological epoch, corresponding to the time of the deposition of each class, and thus indicate their relative ages. They indicate also the successive conditions of the globe as it passed from its gross chaotic state, to a state suitable for the habitation of man, and his companion animals. 3. _The natural history of the_ PRIMITIVE WORLD, _as deduced from_ GEOLOGICAL FACTS, CORRESPONDS _expressly in the_ ORDER _and_ NATURE OF THE EVENTS, WITH THE ACCOUNT GIVEN BY MOSES. 4. The gradual retiring of the primitive chaotic ocean, would give sufficient time for the production of those immense beds of marine animals which are found in the most solid and elevated mountains. During the prevalence of the sea, these beds would form at the bottom, and when it retired they would consolidate, with the mineral deposites, into rocks. In this case the process is supposed to go on in a _quiet_ ocean, peaceably retiring, and leaving the deposition in layers. But we must not suppose the waters were always still, and peacefully retiring. If so, there could not have been such distinct and different deposites, in which different substances sometimes alternate. Moreover, in this case there would have been but one deposition, which would have been regular and continuous, changing its character simply by almost imperceptible degrees, and extending all round the globe, as the globe was at first wholly immersed in water. But this is not the case. There is every reason to believe there were violent agitations, earthquakes, volcanos, tempests, deluges, &c, _occasionally_, during the subsidence of the primitive waters. Hence the _dislocations_, _contortions_, _protrusions of lower rocks through upper ones_, and the _upheaving of the bottom of the seas in various places into ridges, and mountains_, producing a tremendous _deflux of waters_ frequently, which would wash out channels and vallies, and carry off fragments of rocks, &c, into the waters below.