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606 ON THE COAL-FORMATION 



£s to enable me to ascertain its relations with any 

 of the older formations that may occur in a greater 

 or lesser distance from this district. The beds and 

 strata do not differ from those that occur in this for- 

 mation in other parts of the globe where it has been 

 hitherto found : thus, it contains sandstone, bitumi- 

 nous shale, slate-clay, clay-ironstone, greenstone, 

 limestone, and coal. The limestone is sometimes 

 vesicular, and the vesicles are lined with crystals of 

 calcspar ; and the clay-ironstone frequently con- 

 tains impressions of ferns. The sandstone is some- 

 times intermixed with coal, and contains portions 

 of clay-ironstone, in the form of branches and 

 reeds. 



In several places, the strata and beds are tra- 

 versed by veins, composed of a clayey basis, in- 

 cluding fragments of sandstone, and sometimes 

 small portions of lead-glance. Veins of green- 

 stone are said to occur in some parts of the di- 

 strict, but I had not an opportunity of seeing any 

 of them. 



The following section of the formation, as seen 

 on the banks of the river Wear, and which cor- 



i point is not yet ascertained. If a coal formation, as men- 

 tioned by Karsten, and other mineralogists, does occur 

 under the old red sandstone, we may expect to find many 

 extensive deposits of this valuable mineral, in the red 



f sandstone that skirts so great an extent of the Highlands 

 of this country, and which in particular abounds so much 

 in the county of Caithness. 



s 



