LECTURES ON GEOLOGY. Bv Professor SilIiman.
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began by allUdi0g to the comparative IIttIr- ness of our Globe when viewed i0 connection with other parts of the solar system and then referred to the late vOlcanic erDpii0ns on she Islhmus of DareO. as they had been re- ported in the newspapers. One was at Oma0; inc other was at Guatimala. which is said to have been heard at the distance Ofa thousand miles. He said it was very probable there were volcanic operations at the west and south ofour region, and the cause of our DOi having them here might be the gr~Strr thickness of the crust of the earth on which we were per mitted to live. For proof that Coral contains animal matter, lie mentioned that in burning it a smell would be produced like that from the decomposition of animal matter in the fire. The transition rocks he represented as being less crystalized than the Primary.

 The lecturer then proceeded to the Coal formation, which he mentioned as interesting in every respect. It was an evidence Of good ness on the part of the Creator. He had fur nished it for fuel in cold countries where it was most needed. and where no other could be had. Mr. SilIiman glanced at the com bustihles in the world at the diamond which is the same with charcoal, except it's being crystalized at sulphur which is the result of volcanic action; at bitumen and asphalt, at

 petroleum which is exceedingly common in the western states, and which wherever it rises, indicates coal beneath. He referred also to the Pitch Lake in the Island Of Trini- dad, which furnishes pitch for the English Navy. Naptha he considered as purified petroleum, and is the only substance under which potassium can be preserved. Napiha is found around the Caspian Sea, and in the Birnlap Empire.

 The position of coal he said was two miles below the surface of the earth. This distance is estimated by the strata Of rocks and their inclination. By this is meant. not that the coal really lies SO far beneath the surface. as in some instances it is found near or at the surface; but that geolog'cally speaking. its bed is placed, in cOnnexion with formations whose positions are above it, at that distance in the interior; so that if all the upper layers were actually arranged one above the other where coal is found, it would be about two miles from the top.

 Plants, trees, and Ignite are found from $50 to 400 feet below the surface the earth. Vegetation goes on in some instances even be- | low the coal In the neighbOrhoOd of Gin l cinnati trees are found buried 20 or so feet | below the surface. Theseatffe real wood, not being petrified in the least degree. The in- ference from this fact is, that region was once swept by tremendous torrent of waters. which buried up whole forests. MT. Silliman exhibited specimen of beautiful tree from | Hungary which had been converted into sili- ceOus matter. He said the water in which the tree had been placed. must have contain ed siliceous matter dissolved; and hence that kind of 2etrifaci0n. The Island of Antigua abounds with fossils.

 The prOfessor spoke of MT. Witham, l gentleman of Edinhurg, who devised and put l in operation an interesting process ny which he was enabled to ascertain the genus Ot pet 1 riGed trees. There is Sand stone quarry | near the city of Edinburg. down which at the distance of seventy feet has been discovered a petrified tree, sixty feet i0 length. and be- tween five and six in diameter at the base.- Mr. Witham cut of slices from this tree. ce- mented them on glass. and then ground them; from which operation he could ascertain the l structure of the original tree. He found by examination that it belonged to the family of cOnebearing trees such as fir and pipe. Such l trees are found in sand -stone below the coal formation. From these facts it is inferred l that pine trees grew on the earth at a period prior to that of the collaboration.

 Coal is of fossil nature. Real plants are found embedded therein; trees and leaves n | entire expansion. The greater part of the | coal formation is made up of soft and snccu- ient plants; yet there are trees sixty and sev enty feet in height. and two and three feet in [ diameter. In Pennsylvania. ihere arc whole piles of mountains made up of plants. The coal in the state of Ohio exhibits vegetable structure. Geologsts now believe that coal has vegetable origin. Anthracite is consid. cred as older than bitumen.

 The geological structure of the coal. foripa- ton is simple, as was seen from beautiful drawing of the Valley of Wyoming, exhibi. ted by MT. Silliman. There is the shalerock, then sandstone, and then coal with an Occa- sional mixture of iron. A dike of trap some times cuts the coal asunder. when one side of fhe coal is raised much higher than the other Marks of violence are traced tn the coal re- gions.

 In burning, anthracite will not flame. yet bitumen wilL Lignite, of the structure of wood, is anterior to the basaltic columns of Ireland, and will burn. Bituminous lime stone Frequently accompanies coal. In quantity, the coal of Pennsylvania exceeds any other in the world. There are beds in that state of three and four hundred feet in depth. There IS no anthracite beyond the AIlegany. The coal in the Valley of the Mississippi is bitu- men, where there is an immense basis oft.

 Peat is formed upon the surface ofthe coal. N is from vegetable action that goes on in the moss of marshes. The roots ofthe lnosses die and become peat, while the shoots rise upwards and flourish.

 New England is not a coal region because its rocks are of the granite family which do not contain coal, unless in very limited quan- tity. ltis therefore vain to search for coal xs AtNSa ~esh~ ~ T