of the hills considerably steeper than the northern, and sometimes even quite precipitous, where they constitute the boundary of the vallies of the Severn, and the other principal streams that flow through it. None of these hills, in the Shropshire part of the district, exceeds the height of four hundred feet above the level of the Severn at Coalbrook-dale. Another circumstance remarkably characteristic of this kind of sandstone, is the great number of meres, or deep pools, which it contains. The outline of all these pools more or less approaches to circular; they receive no streams, and very often do not transmit any, the loss by percolation and evaporation being nearly supplied by the springs that occupy the middle and deepest part of their bottoms; I say nearly, because all that I have examined bear evident marks of gradual diminution: in many, this change has advanced so far as to convert the whole area, with the exception of a deep pit or two near the centre, into a peat-moss, and some of the smaller and shallower ones are not only entirely filled up, but are even converted to the purposes of agriculture. The above characters seem to identify this rock with the old red sandstone formation of Werner.
That portion of it which lies between the great coal-fields of Staffordshire on the east, and of Shropshire on the west, is about twelve miles wide. The Staffordshire strata dip rapidly towards it in a western direction, while those of Shropshire decline towards it, at a lower angle, in an eastern direction. Whether they actually past under the sandstone, or terminate abruptly on coming in contact with it, has not yet been demonstrated; many intelligent miners are of the former opinion: but to me, the latter appears the more probable, from an observation that was made a few years ago in Welbach colliery near Shrewsbury. In this coal-field, as in the two before mentioned, the strata dip towards the sandstone ; and there
