GEOLOGY. i25 



sandslone. The Breccia is made up of fragments of limestone, evi- 

 dently derived from the valley beyond or west of the mountain, and ce- 

 mented together by a red cement like that of the contiguous red shale. 

 Some are made up of pebbles, or contain them in large abundance. 

 These pebbles are the icater-u-orn fragments of lower rocks, and afford 

 conclusive evidence of the diilerence of age of the different strata. 

 The lower must have been first broken up, their fragments subjected, for 

 some considerable time, to the action of running water, and then these 

 rounded fragments deposited in connection with fine mud or other ce- 

 ment in layers over the broken edges of the lower strata. Every im- 

 bedded pebble and grain of sand, which forms a part of a stratum of 

 rocks is, thetefore, proof sufficient of the agency of water in the pro- 

 duction of stratified rocks. 



Thirdly, the presence of organic remains in stratified rocks proves 

 most iucontestably their aqueous origin. If llieir presence were only 

 occasional or confined to a few. localities they might be regarded as ac- 

 cidental or as not being an essential feature of the rocks in which they 

 occur, but as they are to be found every where, and in many instances 

 in the greatest abundance, they are characteristic, and, undoubtedly were 

 present when the rocks were formed. 



These remains are both vegetable and animal, and consist frequently 

 of the less perishable parts of the plant or animal, the carbon of the 

 former being preserved in the great coal measures, in which the stems 

 and trunks, and even the delicate vegetable structure are yet visible, so 

 that the genus and species of the plant or tree can be identified ; and 

 the bones, and shells, and even excrements of the latter arc found nearly 

 unaltered, so that the animal to which they belonged can be identified, 

 and even the nature of its food determined. In other instances, and par- 

 ticularly in the lower rocks, merely the impressions or casts remain, the 

 original organic matter having been decomposed and displaced by min- 

 eral matter. Tiiis latter class are called pctref actions in which the 

 plant or animal appears to have been converted into stone. * Casts of 

 this kind are tcrbe found in all kinds of rock, limestone, sandstone and 

 flint. It is wonderful with how much accuracy and delicacy these prints 

 are often taken in the solid rock, so much so, that the most delicate leaf 

 of a plant has its fine nerves and lines faithfully represented. Even in- 

 sects and the spider-web have been found mineralized. Besides these, 

 we also find foot-prints of birds and animals, which must have been made 

 on the surface of the rock, whilst yet it was soft sand or mud. These 

 foot-prints arc found on the surface of rocks lying at some considerable 

 distance down in the series of strata, and show most clearly that the rocks 



