Geology and Geography, 425 



west. Mineral veins are exceedingly numerous between these 

 lines, and especially near to that having the easterly direction. In 

 the valley of the Tyne they are parallel to the northern line, and 

 the cross courses, on the other hand, are parallel to the primary 

 line of dislocation. 



Mr John Taylor states that this east and west direction of mine- 

 ral veins is common not only to the whole of Britain, but also to 

 Mexico ; and Professor Phillips, reasoning upon the whole of the 

 facts at present known to him, expressed his conviction that they 

 seemed to indicate the operation of important agencies as yet not 

 brought into account in geological reasoning. 



Remarks were made by Mr Smith, Mr J. Taylor, and Dr Boase. 



Mr Maclaren exhibited sections of the Pentland Hills, and made 

 some remarks on their structure. These hills, he stated, are about 

 fifteen miles in length, and from three to six in breadth. The 

 fundamental rock is transition slate accompanied by greywacke in 

 vertical strata, which are covered unconformably by conglomerate 

 and various felspar and claystone porphyries, in beds dipping to 

 the south-east, at angles varying from 10° to 35°. Beds of con- 

 glomerate, alternating with greywacke, abound in the western 

 part ; in the eastern, the greywacke is accompanied chiefly by 

 felspar, claystone porphyries, and amygdaloids. A vast mass of 

 sandstone forms the termination of the chain on the west, and rises 

 to the height of nearly 1800 feet in the two Cairn Hills. The age 

 of the hills, or the period of their elevation, is indicated by the po- 

 sition of the secondary rocks on their flanks. The sandstone of 

 the Cairn Hills inclines against the transition rocks, at a considerable 

 angle, on the north side, and at Craigintarrie appears in beds almost 

 vertical. On the south side, the older strata of the coal formation 

 are found at various places, in a position highly inclined or vertical, 

 while a newer portion of the same series is found in horizontal 

 beds, or dipping in towards the hills at a low angle, and in juxta- 

 position with the former. It follows that the elevation of the tran- 

 sition rocks took place at a period subsequent to the deposition of 

 the older, but previous to the deposition of the newer, part of the 

 coal formation. 



Mr Murchison gave an abstract of Dr Rogers' report on the geo- 

 logy of North America, and read extracts from this valuable and 

 elaborate memoir. The following are the conclusions drawn by the 

 author. 



