88 DR THOMSON ON THE STRATA OF BERWICKSHIRE. 



It is to the rougli-quartzose sandstone that is observed at the surface 

 near Greenlaw-wells, that I am inclined to attribute the position of 

 the fossil tooth, which was found by one of our members, the Eev. Mr 

 Knight of Ford. The rocks at Ford and at Greenlaw-wells seem to 

 approach each other in their composition, and both are near the sur- 

 face. Dr Grant, to whom I shewed the specimen, was of opinion that 

 it belonged to a fish. It consists essentially of phosphate of lime, but 

 effervesces when it is touched with acid. The minuteness of the size 

 of the specimen, however, has prevented me from obtaining any 

 satisfactory results in reference to its quantitative analysis. 



Dr Johnston informs me, that the Lepidodendron Stenihergii has also 

 been observed at Ford, in the same sandstone, and impressions of ferns 

 (Sphenopteris?). The position of the locality where these remains 

 are observed, is about two hundred yards from the mouth of a coal 

 shaft. 



The sandstone consists of a yellow calcareous basis, mixed with clay, 

 which serves to agglutinate irregular grains of white quartz, and 

 exhibits cavities lined with carbonaceous matter. The Greenlaw-wells 

 sandstone is likewise yellow, coarse, and consists of large grains. 



The Cooper eye coal, although thin, when compared with coal beds 

 in other places, forms a good burning material. The levels formed 

 during its working are on an average 3-2- feet high. The coal is 

 removed between two levels, and its place supplied by the limestone, 

 which Kes on both sides of the coal. The immense pressure frequently 

 crushes these supports, and when any considerable quantity of country 

 has been mined, the surface sinks. The effect of this subterraneous 

 quarrying is very visible upon Duddo Tower, which has been rent 

 from to];) to bottom, in consequence of being undermined, notwith- 

 standing that it is situated upon a considerable eminence. In traversing 

 the different levels I observed in one place a rent, the opposite surfaces 

 of which appeared brilliantly polished. I found, upon attending 

 minutely to the adjoining strata, that this was caused hy one portion 

 having subsided, while the corresj^onding jiart had remained stationary. 

 The consequence had been violent pressure upon both surfaces during 

 the subsidence of the former. 



I made many inquiries with regard to the occurrence of accidents in 

 the mines in this neighbourhood, and learned that they were very 

 uncommon. Inflammable air or carburetted hydrogen never appears, 

 its occurrence being confined to deep mines. The only inconveniences 

 arise from bad ventilation when the levels have been driven to a great 

 extent, and the occasional disengagement of carbonic acid, which takes 

 possession of the extremity of a level, and cannot readily be expelled. 

 A man was lately kiUed by the influence of the latter cause. The 

 consequence of the rarity of these accidents is, that no precautions are 

 deemed necessary for the safety of the miners. No safety-lamps are 

 employed, — a candle stuck in a piece of clay sufficing for all necessary 



