Correspondence. 3S1 



THE SEA AGAINST THE PLOUGH.— REPLY TO Me,. G. POULETT 



SCEOPE. 



To the Editor of the GtEOlogical Magazine. 



Sir, — I can scarcely suppose that the banks and lynchets^ with 

 which Mr. G. Poiilett Scrope is most familiar are of the same nature 

 as those which I believe to be old sea-coast lines, and which every 

 Lyellian geologist should expect to find in situations favourable to 

 their formation and preservation. The terraces in the Cretaceous and 

 Oolitic districts of the south of England, to which I have all along 

 alluded, are generally speaking from 15 to 40 feet in height, and 

 from 15 to 60 feet in breadth ; but many of them are much smaller, 

 and not a few very much larger, embracing even the whole of an 

 escarpment. The smaller, however, are often so associated with the 

 larger as to leave little doubt of a common origin.^ They may be 

 seen in great variety between Mere and Hindon, between Blandford 

 and Sturminster, in the neighbourhood of Bridport, etc. They pre- 

 sent the same aspect as many lower level terraces in Somersetshire, 

 commencing on the Coast, and running inland beyond Glastonbury, 

 and in Dorsetshire near Bridport harbour, etc. They are likewise 

 similar to many systems of terraces in the neighbourhood of the 

 Moray Frith, and the Great Glen, in Scotland. That the inland 

 terraces of Dorset and Wilts are not covered with " shingle or rolled 

 pebbles " is no presumption against their marine origui, for it is now 

 well known that on shores fringing steep slopes, where there is 

 little faciKty for the drifting of materials, the sea often fails 

 to rormd fragments of rock, and that chalk flints under ordinary 

 conditions require to be subjected to a second or even third stage or 

 period of attrition before they can become roimded. [Lyell's 

 Elements, p. 370]. 



It is true that a section of several lynchets near Warminster, 

 kindly furnished by Mr. Codrington, F.G.S., exhibits an apparent 

 addition of made ground to their general profile, in a way however 

 that the plough will not explain ; but it is only reasonable to sup- 

 pose, as I have before remarked, that man may have tampered with 

 and rendered less sloping the platforms of these and other terraces, 

 or even imitated nature in making entire terraces. Still there are 

 peculiarities connected with the fundamental form, structure, and 

 arrangement of those I have observed which the sea only will account 

 for, such as the extent to which their profile corresponds with the 

 indentation in the rock beneath ; their frequent waved or inclined 



^ See Mr. Scrope's Article " The Terraces of the Chalk Downs," in the July 

 Number of the Geological Magazine, p. 293. 



- The extent to which these terraces have preserved their shai'pness of outline, sup- 

 posing them to have been formed during a pre-glacial submergence, furnishes no real 

 objection to the theory of their marine origin, as grass-covered lands away from the 

 com'ses of temporary or permanent streams are capable of preserving their surface- 

 configuration for an indefinite period. Mr. G. Poulett Scrope himself, in the article 

 I am now answering, attributes to grass a power of checking the descent of silt, o-reater 

 than would be required for ordinary surface-protection. 



