250 Maiv — Distribution of White Clays and Sands, 



to tlie existence of fissures in the subjacent Limestone rock, and 

 down which, the water is carried mixed with particles of clay. A 

 curious instance occurred a few months ago, shewing the insecurity 

 of this material to build upon. The landlord of the village inn had 

 been entertaining some guests in his best parlour until a late hour 

 on a Saturday night, when on the following Sunday the room fell 

 into an unsuspected chasm in the foundation." 



" The question now presents itself, at what time was this bed de- 

 posited? To this I can only answer, that it is my belief it was 

 deposited before the first glacial action took place, and that it may 

 be possibly coeval with some of the later Tertiaries, as, for instance, 

 the Norwich Crag. It occurs beneath all other drifts ; it is unmixed 

 with Boulder mud. The fragments of contained rocks are mostly 

 angular, and although I have bestowed much time in the search for 

 indications of glaciation, yet, in so far as I can see, the blocks are 

 unmarked by strige or groovings. I further consider this deposit 

 to be a very ancient one, from the circumstance of the absence of 

 calcareous matter from its composition, for it can scarcely be 

 imagined that a marine deposit of this character could have been 

 formed ,upon and among calcareous rocks without embedding 

 some fragments of limestone in its substance. Yet I have 

 failed to find any limestone at all amongst the pieces of rock that 

 are scattered through it ; and the clay and sand yield only the most 

 infinitessimal trace of lime, when exposed to the most delicate of 

 all tests — oxalate of ammonia. I infer that there was a very long 

 period after the deposit of this bed, and prior to the deposit of 

 the Boulder-clay, during which rain-water permeated it in all its 

 parts, and gradually carried off all calcareous matter. It is owing 

 of course to the absence of lime that this clay is so capable of being 

 used as a fire-clay. I need not remark that I have not found 

 any shells in this bed ; as if they ever existed there, which is not 



Fig. 7. mite-clays. Sands, and Pebble Beds ;^ery probable, they would have 

 overlain by Glacial TiU, Eibden Pit, ^^en long since dissolved and 

 Weaver Hills. carried away." 



Under the direction of Mr. 

 Brown, I have recently had 

 an opportunity of examining 

 some of the pits on the Weaver 

 Hills, and was much struck 

 with the close resemblance of 

 the deposit, both in position 

 and mineral character, to the 

 white clays and sands of the 

 Mountain Limestone district 

 of North Wales. Some of the 

 complications of arrangement 

 . ... Bouider-ciay Till. b. Ditto" fiiHng up'^a crack ^^re Very remarkable. The 



in (c) White-clay Sands and Pebble-beds subse- sand and clav strata OCCUpvins: 

 quently shifted. ,, -.. , "^ ... V- 



the limestone cavities being 

 sloped and twisted into strange contortions, here and there standing 



