68 Mackintosh— The Sea v. Rain and Frost. 



But with the subaerialists resemblance has little weight. They 

 virtually ignore one of the fundamental principles of inductive 

 reasoning — similar effects must be referred to similar causes. The 

 inductive geologist is not required to explain the absence on any 

 particular spot of certain minor indications' of the former presence 

 of the sea, which may never have existed, or which may have 

 gradually disappeared, while he can point out not only the strictest 

 resemblance between new and old sea-coast rocks, but a peculiarity 

 about the latter which the sea only could have formed. Among the 

 peculiar shapes communicated by the sea may be mentioned the 

 arched buttress, which may be found projecting from many inland 

 cliffs. There is one near Torquay, on the right-hand side of the 

 lower road leading to Teignmouth ; another behind Mrs. Weather- 

 head's house at Brimham, near Harrogate ; a third near the base of 

 the Cefn cliff, near Denbigh, and many others which might be 

 mentioned. 



Bemarhs on the Cotswold Escarpment. — Sir Eoderick Murchison has 

 not only added a new geological world to that previously known, 

 but he has evoked from the grave of bygone time a sea rolling 

 through the " Straits of Malvern," dashing against its south-eastern 

 Oolitic barrier, and scooping out its shores into " combes and bays, 

 beautifully rounded."^ In the neighbourhood of Cheltenham and 

 Glou^cester, the escarpment has been quarried at various periods, 

 and it is difficult to ascertain which parts have retained their natural 

 forms. The same difficulty applies to the debris under and on the 

 sides of the escarpment. In the neighbourhood of Crickley there 

 are some rocks which present no trace of their having ever been 

 quarried, and which look very much like sea-coast rocks. Certain 

 parts have been worn into holes, and between them the rock has 

 been smoothed and rounded. To the south of Mr. Odell's house, 

 above Crickley, the smooth part runs along in the form of a groove, 

 or nearly horizontal depression.^ 



^ RouTided pebbles are not a necessary indication of tbe former presence of the 

 sea. The degree of roundness, or angularity, will depend on the nature of the stones, 

 the distance they haye rolled, and the length of time the area they occupy remains at 

 a stationary level. In the Midland Counties, drift composed of rounded pebbles, 

 and drift composed of angular flints, graduate into each other on the same horizon. 

 There, also, drift, interstratified with beds of sand containing sea-shells, may be seen 

 on the same horizon with and graduating into drift in which no sea-shells have yet 

 been discovered. 



* Buckman's Straits of Malvern. 



3 See Lyell's Elements of Geology. In the two lines of cliff (Inferior Oolite) 

 which have been more or less quarried above and beyond Leckhampton, one may see 

 a very striking illustration of the way in which atmospheric action tends gradually to 

 obliterate a precipice. The weathering, so far as it affects the compact rocks, is 

 chiefly limited to parts that overhang, which are gradually falling down, one block or 

 fragment from under another, thus tending to convert an overhanging into a vertical 

 cliff. The next stage of the process is not connected with the cliff itself, but consists 

 of streams of oolitic fragments from the loose incoherent bed on its upper surface. 

 These streams give rise to ridge -like buttresses in front of the cliff, the tendency 

 being to conceal the cliff under a slope of debris. In this way, in all probability, a 

 great part of the ancient sea-wall of the Cotsvvolds has been converted into a grass- 

 covered slope, and quarrying operations have in some places been equivalent to 



