Sandstone, and sandstone-slate, are the next members of this series. The sandstone-slate resembles mica slate so much, that it has been sometimes confounded with it. To the sandstone succeeds the coal formation, which contains friable sandstone and slate-clay. Lastly, the series is terminated by bituminous wood and earth coal, accompanied with sand and clay ; which latter correspond to the sandstone and slate-clay of the im mediately preceding formations.
A material division of this beautiful series takes place with grey-wacke. From it, upwards, all the members are completely chemical. On the contrary, in the lower, the chemical is combined with mechanical, and only the lowest links of the series are completely mechanical pro ductions.
S. Trap Formation-Suite: In this series, all the formations have a great :.!sem blance to each other ; yet all of them bear very distinct marks of the period of their formation. The oldest or primitive greenstone is highly crystalline ; the new er or transition is less crystalline ; and in the newest or ficetz-trap, it approaches to earthy, as appears in basalt, and more particularly wacke, as the lowest links or farthest removed from the highly-crystalline primitive greenstone.
4. Porphyry Formation-Suite.
The first memher of this series, or which is denomi nated the Old Porphyry Formation, occurs in great un broken beds, in gneiss, and its basis is hornstone. The second member, or what is denominated the Newer Por phyry Formation, occurs in unconformablc, over-lying, and broken stratification. Its basis is clay-stone, pitch stone, Ecc. The third and last member of this suite is probably the clay-stone, and porphyritic-stone which occurs in the coal-formation.
5. Gypsum Formation-Suite.
The oldest member of this formation occurs in mica slate and clay-slate. The second member is that which accompanies salt, and with which salt-springs are con nected. It lies over the old flcetz-limestone, and is covered by the second flcetz-sandstonc. The third and last member is what is denominated the second gypsum formation of the flcetz period. It lies over the second sandstone formation, and under the second limestone of the flcetz period.
6. Salt Formation-Suite. This series contains only two members. The first
and oldest occurs along with the oldest flcetz, gypsum, and the newer is that which is still forming at the bottom of thc lakes.
7. Coal Formation-Suite.
Thin is a very interesting series. Inflammable mat ter occurs in considerable quantity only in the newer formations. The small portion that occurs in primi tive mountains, is carbon, uncombincd with bitumen. In the newer formations, bitumen makes its appearance ; and in the newest formations, as in the thrtz-trap, we find immense accumulations of bituminous inflammable matter.
It was only after the deposition of these immense re positories of inflammable matter in the fIcetz-trap, that volcanoes could take place : they are, therefore, to be considered as new occurrences in the history of nature, although they may extend far beyond historical record. The volcanic slate appears to be foreign to the earth— a circumstance that points out its great antiquity.
8. Serpentine Formation-Suite Contains but two members; the older, that which occurs in a conformable position with the primitive rocks; and the newer, that which overlies the primitive rocks.
The phenomena presented by all these formations, Werner remarks, coincides with the hypothesis of the gradual and universal diminution of the waters of the globe. We shall conclude what relates to that subject, by a general observation respecting the effects which would be produced on the surface of the earth by the diminution of the water ; and then state the arrangement of the different formations, founded on the preceding observations respecting their order of succession.
It is evident, that as the water diminished, and the dry land appeared, the motion of the water would be altered, and its currents receive new directions, or be divided. These changes must have had a very powerful effect on the former surface of the dry land, and, by destroying a part of the earlier formations, would afford matter for newer formations.
We have already. in Chap. IV. established five classes of rocks, disiinguis!.ecl by the names primitive, transi tion, secondary, alluvial, and volcanic. We shall now describe these in the order just mentioned, beginning therefore with those of the primitive class.