ALUJt MINES OF AUBiy. 333 



itrata is almost always in the longitudinal direction of the 

 hills. As to their dip the strata are generally set on edge: 

 they hang in all directions, and at every possible angle from 

 perpendicular to horizontal : the strata of two neighbouring 

 hills are seldom seen to incline the same way ; and, when 

 this does occur, it is at different angles. The hills nearest 

 together offer striking varieties, and frequently singular for 

 the nature, order, and thickness of the strata. It is even 

 in vain to seek for some similarity of structure in certain 

 places, -where the strata that skirt a Valley are placed so, 

 that they would come to rest against the strata on the other 

 •ide, if both were sufficiently prolonged. Hence it may be 

 conjectured, not only that the surface has been completely 

 broken up, but that it has experienced considerable degra- 

 dations subsequent to this disruption. 



The coal ground is almost wholly formed of a gray sand- Strata, 

 itone, commoly fine-grained, and composed of feldspar, 

 quartz, and some particles of mica. The mean thickness 

 of the strata is about a yard: some are found, that are 

 more than ten yards thick, others not a tenth of a yard. 

 In the midst of these sandstones are seen thick strata of 

 puddingstones with granitic fragments ; and strata, generally 

 thin, of gray or blackish argillaceous schist exhibiting some 

 impressions -of vegetables. Coal is found throughout al*The coaL 

 most the whole of the basin. The outcroppings are very 

 numerous, and occur indiscriminately at the foot, on the 

 acclivity, toward the summit, or on the ridges of the hills. 

 The number of the seams, their thickness, and their dis- 

 tance from each other, vary in every hill. They are al- / 

 most all thick enough to be worked. There are seldom 

 more than four in one hill. Their mean thickness is in ge- 

 neral from two to six yards; but in some places it is truly 

 astonishing, and hitherto unexampled. The vertical seam 

 now working at Lassalle is 103 met. [338 feet]. Its course 

 is perfectly regular, and known, for it is worked by means 

 of levels extending from the roof to the wall. 



From what has been said it is obvious, that the coal of Management 

 this country is as easy to extract as it is abundant. It is °^ ^^* 

 worked in fact in a number of places, and almost every 

 where by means of levels. The coal is embarked on the 



Vol. XXIX. — Supplemext. A a river 



