YORKSHIRE NATURALISTS AT PICKERING. 



275 



Mr. Cole pointed out that, whereas at the former place the Lower Calcareous Grit 

 was resting on the Oxford Clay of the valley bottom, yet on ascending Newtondale 

 it has risen at Levisham station to the tops of the hills on either side. On 

 algihting a gradual ascent was made from Levisham to the striking moorland ter- 

 race formed by the Kellaways Rock, which, viewed from the railway, shows such 

 a bold and precipitous front. On passing over this moor it was observed how much 

 it resembled the appearance Of our millstone grit moors nearer home. At one 

 point a disused engine-house was noted, and on inquiry it was found that the thin 

 and uncertain seams of coal to be found in the estuarine beds of the lower oolites 

 had aroused at one time a spirit of speculation, doomed, however, to a disastrous 

 close. During this moorland walk continual opportunities presented of grasping 

 the physical structure of the district, and the changes effected by denudation. As 

 Mr. Cole pointed out, the bold escarpment of the tabular hills just above us must 

 at one time have extended northwards to the anticlinal, and is now gradually 

 receding, entirely from the effects of sub-aerial denudation. As regards the valleys 

 of the district, they nearly all coincide in their direction with the dip of the strata, 

 showing that the latter was the cause of their initial course, and further, as all 

 those valleys running south cross the tabular hills, the courses of the streams must 

 have been determined before the formation of the escarpment. Making a further 

 ascent up the slopes of the Oxford clay, the extremely isolated, yet romantically 

 situated, inn at Saltersgate was reached, some 950 feet above the sea-level, after 

 which, in a few minutes' walk, Mr. Cole effected somewhat of a surprise, by sud- 

 denly disclosing the main object of the day, the Hole of Horcum. The party was 

 now on the summit of the tabular hills, and standing on the lower calcareous grit, 

 by which they are capped, and before them lay stretched a gigantic natural amphi- 

 theatre, half a mile across in some places. Here, again, was a magnificent example 

 of erosion arising from the drainage of its slopes and the small springs issuing from 

 the Oxford clay. The Hole of Horcum forms what is geologically known as an 

 ' inlier,' which one geologist defines as ' the isolated exposure of an underlying bed 

 amidst others which are geologically above it,' or, more briefly, is an area of older 

 strata surrounded by one of younger. Thus, at the Hole of Horcum the bottom is 

 composed of the Kellaways rock, the sloping sides of the Oxford clay, and the 

 rugged edges at the top of the lower calcareous grit. At this point Mr. Cole drew 

 special attention to the narrow ridge which encloses the Hole of Horcum on the 

 north, destined to break down before the slow but sure process of denudation. 

 Mr. Cole now led the way across the moor to a higher elevation called Winny Neb, 

 and right in front rose the weird and conical summit of Blakey Topping, so closely 

 connected with the mysterious worship and sacrifices of the Druids. This peculiarly- 

 shaped' hill is about 140 yards in length, narrow on the top, and perhaps elevated 

 about 200 feet above the moor on which it stands. Blakey Topping is, geologically 

 speaking, an outlier, also the result of denudation, the summit being of lower cal- 

 careous grit, and the sides of Oxford clay. The reverse of the description of an 

 inlier must be applied here, the younger strata being surrounded by the older. 

 From this point there was, too, a magnificent view. A few miles away stretched 

 that remarkable ridge called Langdale Rigg, which, as Mr. Cole said, although 

 nearly two miles in length, is on its summit extremely narrow, in some places not 

 above fifty yards wide. On the right was the grand sweep of escarpment known 

 as Cross Cliff, and far away in the distance could be seen Oliver's Mount at Scar- 

 borough. The view of these flat-topped and numerous nabs or escarpments over 

 such a wide area presented a striking appearance. Thne now necessitated a vigorous 

 and health-inspiring walk over the moors back to Levisham, thence by rail to 

 Pickering. After tea the evening was too fine for the transaction of any but strictly 

 necessary business, and accordingly the enthusiasm of the geologists led them to those 

 fine sections in the middle oolites near Pickering Castle. The clink of the hammers 

 was soon heard, and many fine specimens speedily extracted, among which maybe 

 mentioned Phasianella striata, Cerithium mitricatnm, Chemnitzia heddingtonensis, 

 Belemnites abbreviates, Ammonites cordatus, A. plicatilis, Cncullea corallina, 

 THgonicB, Nerincea, Ostraa, Pecten, Gervillia, &c. Also some fine typical speci- 

 mens of the rock were obtained, showing well both the characteristic oolitic and 

 pisolitic structure. A bed of a peculiar stone, of an argillo-calcareous character, 

 locally termed ' throstler,' and used in the manufacture of cement, was noted. 



Sept. tS86. 



