392 



Professor J. Phillips, 



[March 13, 



ings of the feeble parts, and the flutings and 'striations of the 

 harder masses — a phenomenon also exhibited in the new railway 

 tunnel in many examples. 



The great fault to which attention has thus been called, as the 

 last great line of movement traceable in the Malvern district, 

 appears to have affected the strata before the Mesozoic age began 

 ■ — there is no trace of new red deposits on the west of it. There 

 are, however, reasons for thinking that movements on the line of it 

 were continued into the period of these deposits. This has lately 

 been put in strong evidence by the progress of the railway tunnel 

 between Great Malvern and Malvern Wells. Here the line of the 

 fault has been crossed, and found to be (as indeed it also appears 

 to be at North Malvern) complicated by many fissures, and much 

 movement among the displaced masses of hard rock on which 

 " slickensides " abound ; the triassic beds being reared against it 

 as much as 30° and 40"^, a greater angle than my observations in 

 1842-4 led me to expect, but leading to the same conclusion : viz., 

 that the last great movement on the line of fracture extending from 

 the district of Tortworth, by Mayhill, Malvern, and Abberley, was 



not completed till the Mesozoic ages had begun. Thus, then, 

 finally, the section across the Malvern Hills | shows movements 

 having the . characters sketched in the diagram C, in which it may 

 be remarked that the folds of the strata seen on the west of the 

 Malvern, are broad and gentle at a distance from the hills, but 

 sharper and steeper, and even reversed in dip, near to the syenite. 

 This is a local example of a general truth, some time since specially 

 indicated along the AUeghanies, by Professor Rogers. The curva- 

 ture of the beds in the Malvern district is so great, that the 

 horizontal extent now occupied by them is less by one-fourth or 

 one-third of a mile than the extent measured along the curvature — 

 an indication that in these foldings of the strata much lateral com- 

 pression has occurred. If we suppose a limited basin in which the 

 strata have descended by continual depressions one, two, or more 

 miles, to be again elevated, a compression of the strata in the pro- 

 portion of the arc to the chord must be the result — lateral pressure 

 as an effect of vertical movement — foldings to adjust the length of 



