D. MACKINTOSH ON" HIGH-LEVEL MARINE DRIFTS. 



363 



Y. — High-level Gravel and Sand near Llangollen. 



Around Llangollen and elsewhere in North Wales a kind of 

 loamy clay, or clayey wash, often forms the surface of the ground, 

 and conceals what lies underneath. It may have been partly 

 deposited as the land sank into deeper water, and partly during the 

 rising of the land. The existence of an unknown extent of gravel 

 and sand under this clay at a high level might never have been dis- 

 covered but for the excavation of a pit a short distance east 

 of Ehos Pengwern farm, in a field nearly 1200 feet above the 

 sea-level. Under about 3 feet of clay, with perfectly angular 

 stones, there is an unknown thickness of fine and coarse gravel and 

 sand arranged in laminae more or less arch- shaped. The stones are 

 considerably rounded and smoothed, though the sand does not 

 appear to have been very cleanly washed. There can, however, be 

 no doubt about its being a sea-coast or shallow-sea deposit (though 

 I could not find any shell-fragments), as its situation precludes the 

 idea of its having been accumulated by any freshwater stream. 

 More extensive excavations are required to show both its horizontal 

 and vertical extent. At lower levels down to about 500 feet or 

 400 feet above the sea the drift contains scarcely any rounded 

 stones, while it is particularly worthy of remark that in a pit at 

 the east end of Grouse-box Hill (not far from Pengwern pit) about 

 1300 feet above the sea, the gravel is perfectly angular, and con- 

 tinues so up to the summit of the hill, 1715 feet above the sea. 



YI. — Remarks on the High-level Gravel and Sand of 

 Macclesfield Forest. 



The identity in level of the Prondeg and Macclesfield-Forest 

 deposits reuders it appropriate that some notice should be taken of 

 the latter. They were discovered by Professor Prestwich in 1862, 

 near the Setter Dog Inn, at an altitude between 1100 and 

 1200 feet above the sea. He found more or less clay both below 

 and above the shelly gravel and sand ; but I should be inclined to 

 regard the clay above as on a horizon distinct from that of the 

 upper Boulder-clay of the plain of Cheshire, and more or less allied 

 to the patches of clay or loam which overlie the high-level gravel 

 and sand of North Wales. I found the shelly gravel near the 

 Setter Dog Inn graduating eastward and upward, in the direction of 

 Shining Tor, into angular gravel at a height of more than 1350 feet 

 above the sea. At a greater height, in an easterly direction, all the 

 gravel is angular; but S.E. of the Setter Dog, in Chapel Lane, 

 rounded erratics may be found up to about 1400 feet. Prom these 

 facts it would appear that the two gravel districts, the one on the 

 west (Prondeg), and the other on the east (Macclesfield Porest), cor- 

 respond almost exactly in level. — Near Clulow Cross, some distance 

 south of Macclesfield Forest, Mr. Sainter (of Macclesfield) has dis- 

 covered gravel and sand with sea-shells about 1130 feet above the 

 sea (see his interesting work entitled ' Rambles round Macclesfield'). 



