A Ramble in West Shropshire. 349 



The Stiperstone range, upon which he stands, is pronounced 

 by Sir R. Murchison to be the equivalent of the Lingula flags 

 of North Wales ; and as he would find no perceptible differ- 

 ence in the inclination of these two strata (the Lingula and 

 the Llandeilo) in this neighbourhood, both dipping at an 

 equally high angle towards the west, he might at first be 

 led to suppose that they succeeded each other in point of 

 time, as they do in position. There is, however, reason 

 to believe, as Professor Ramsay has pointed out, that a 

 stratum of great thickness, called the Tremadoc slates, was 

 deposited between the era of the Stiperstone formation and 

 that of the overlying Llandeilo flags. It would be impossible 

 here to repeat all the reasons which the professor has set forth 

 in his most interesting and instructive paper on li Geological 

 Breaks," as leading him to this conclusion. But it will be of 

 interest to state the circumstances under which, according to 

 him, such breaks occur, since the geologist has frequent oppor- 

 tunities of witnessing instances of them on a minor scale ; 

 indeed, every section of a gravel and sand-pit furnishes 

 illustrations of them. 



The omission of such a stratum as this, found elsewhere, must, 

 he says, arise from one of three causes: either, 1, the lower rocks 

 were, at the time of its deposition, raised above water in the 

 particular spots where it is omitted, and only submerged when 

 it had been completed ; 2, the deficient stratum may, indeed, 

 have been deposited over the entire area, but was subsequently 

 in parts washed away or denuded ; or, 3, it may have been 

 deposited in some parts, and not in others. Instances illus- 

 trative of the two latter of these causes are seen in every river 

 deposit. The stream, sometimes diverted from its ordinary 

 channel by the impetus it receives in a high flood, deposits a 

 quantity of debris from high grounds in places where there 

 had been but little previously, while in others it carries off the 

 sand and stones which had been deposited. Of course, illus- 

 trations of upheaval can only be studied on a large scale; 

 but it is possible, by attentively observing the layers of gravel 

 so often exposed to view in a river bank or quarry, to arrive 

 at a solution of some very interesting geological phenomena 

 relating to this subject ; and this study I would specially com- 

 mend to persons who live far removed from the more striking 

 manifestations of geological disturbances, in uninteresting (as 

 they are called) and level countries, where, from the nature 

 of the ground, the slow and sluggish streams wend their 

 way, or on the sea-shore, where over banks of sand and mud, 

 each ebb and flow of the tide leaves its own deposit, or 

 carves out and modifies those previously made. 



Here, on a stupendous scale, it is believed that some such 



