VOL. XXX.] PHILOSOPHICAL TRANSACTIONS. 401 



earth which is now manageable by the plough, may possibly in time assume the 

 same density, at least not far below the surface ; for in this very cliff the upper 

 strata are still clay, becoming the harder the deeper. 



What animal this has been, for want of a natural history of skeletons, it is 

 impossible to determine; but we generally find them to be amphibious or marine 

 animals. Why such, rather than many others, should chance to be thus en- 

 tombed, may be owing to their being able to live much longer than terrestrial 

 animals in that collection of waters, even till they began to abate and fall away 

 into their destined receptacles; so that while the bodies of the rest, soon 

 perished, were corrupted, and their bones separated and dispersed much earlier; 

 this skeleton, with others of the like kind, fell entire into the fissures of this 

 bed of clay, which has since turned into stone, and afforded this noble monu- 

 ment and pregnant proof of that general inundation. 



Observations on the Strata in the Coal-Mines of Mendip, in Somersetshire. By 

 John Strachey, Esq. N° 36o, p. 968. 



Suppose fig. 1, pi. 11, to represent the section of a coal country, and to 

 take in about 4 miles, from the north-west to south east, which may be applied 

 to the veins of coal as they lie at Fariugdon-Gourny, and at Bishop -Sutton, 

 near Stowy, in the parish of Chew-Magna in Somersetshire. 



In searching for coal, they first look for the crop, which is really coal, though 

 very friable and tender, and sometimes appears to the day, as they term it ; or 

 else for the cliff, which is a dark or blackish rock, and always keeps its regular 

 course as the coal does, lying obliquely over it. For all coal lies shelving, like 

 the tile of a house, not perpendicular nor horizontal, unless it be broken by a 

 ridge, which is a parting of clay, stone, or rubble ; as if the veins were dis- 

 jointed and broken by some violent shock, so as to let in rubble &c. between 

 them. The obliquity or pitch, as they term it, in all the works hereabout, is 

 about 22 inches in a fathom ; and when it rises to the land, it is called the crop, 

 but in the north basseting. In the works near Stowy, and at Faringdon, it 

 rises to the north-west, and pitches to the south-east; but the farther they 

 work to the south-west, the pitch inclines to the south ; and e contra, when 

 they work towards the north-east. So likewise they observe as they work to 

 the south-west, when they meet with a ridge, it causes the coal to trap up, that 

 is, being cut off by the ridge, they find it over their heads, when they are 

 through the ridge : but on the contrary, when they work through a ridge to 

 the north-east, they say it traps down, that is, they find it under their feet. 



Coal is generally dug in valleys or low grounds. The surface in these parts 



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