44 On the Coal-field of Sutherland. 



The first of these to be noticed, is a conglomerate with a 

 basis of limestone, containing generally fragments of argil- 

 laceous schist (shales) or of sandstone, or both, or fragments 

 of other limestones. More rarely it contains fragments of 

 gneiss and of granite, and occasionally also of quartz and of 

 felspar. This conglomerate, from the places in which it oc- 

 curs, seems immediately to follow the fundamental conglo- 

 merate already described ; although, from the nature of its 

 position in the sea, the contact cannot be traced I I'coiildnot 

 discover it in those parts of the field most remote from the 

 granite ; although it may exist deep beneath the surface, where 

 the strata are inaccessible. This position is indeed to be ex- 

 pected ; as it approaches very nearly in character to the funda- 

 mental conglomerate ; differing from it in little else than the 

 smaller sizes of the fragments, and the calcareous nature of 

 the basis. 



The strata which seem to follow next in order to this, con- 

 sist of a grey limestone, varying in its aspect in different parts. 

 It is sometimes large, granular, or else of a fine grain, and 

 very smooth, even fracture^ and it is also occasionally schistose. 

 In some places it alternates with thin beds of shale. In others 

 it contains fragments of charcoal ; or else the calcareous sub- 

 stance is intimately mixed with carbonaceous matter, or the 

 coaly ingredient alternates in thin laminae with the limestone* 

 These parts of the calcareous strata, I must, however, remark, 

 seem to be the upper part of this deposit. 



The reasons why it is judged that these limestones follow 

 immediately after the calcareous conglomerate are, that their 

 position on the shore where they occur, seems to justify that 

 conclusion, and because, in other cases, it is remarked, that 

 where a bed of conglomerate, similar to the fundamental one 

 of this place, is followed by a calcareous conglomerate, that is 

 succeeded by simple calcareous strata. The causes of this 

 order of succession must be very obvious. 



Other limestones in this part of the series consist solely of a 

 calcareous conglomerate; that is, the basis is a simple lime- 

 stone, containing imbedded fragments of other limestones. But 

 these also seem, like the carbonaceous beds, to belong to a 

 higher part of this series. 



The organic remains which occur in the calcareous strata, 



