142 Miscellaneous — Mr. Whitaker's Lecture. 



Boulder-clay, though a characteristic feature in the formation, have 

 added but a small amount to its hulk, and therefore can by its 

 weight have had but a slight eifect iu causing subsidence. 



As depression of the land, not only in recent but also in Paleeo- 

 zoic formations, has constantly occurred simultaneously with that of 

 large accumulations, it therefore appears to me that we are at all 

 events justified, if not compelled, to consider that the one is depen- 

 dent upon the other, unless indeed it may be hereafter proved that 

 there has been some other influence acting during such periods and 

 in the same localities, having as great a power in inducing it as the 

 pressure of such immense masses must occasion. 



There may be greater grounds for doubt in attributing that sub- 

 sidence which has resulted in forming the harbours of Portsmouth 

 and others on the Southern coast, to the weight, not of a shingle 

 beach, but of large accumulations in the English Channel, arising 

 from the rapid waste of the cliffs by marine denudation, and which 

 have been carried by tidal and other currents towards the east, 

 because it is a solitary example, and there are no means of estimating 

 what may be their thickness at a distance of some miles from the 

 land, where the deposit is probably greatest ; but at Spithead, where 

 it must be comparatively thin, it was pierced during the erection of 

 the forts to the depth of 54: feet without penetrating through it. 



Chaeles Eioketts. 



22, Aegtle Street, Birkenhead, Feb. I8th, 1873. 



3yLisc:HiXiii.^^:]^:BOTJS. 



NEWBUET DISTRICT FIELD-CLUB.i 



In the first place the details of the beds shown in the pits were 

 noticed, beginning from the top. The highest part of the section is 

 in brown London Clay, with its marked " basement-bed," hei'e con- 

 sisting of about ten feet of brown loam, or sandy clay, with casts of 

 shells, and with a layer of flint pebbles at the bottom. Below the 

 London Clay there is a good exposure of the formation known as 

 the "Woolwich and Eeading Beds," here about 60 feet thick, and 

 divisible into three parts — the uppermost consisting almost wholly 

 of variously coloured mottled plastic clays, often used for the manu- 

 facture of common pottery ware, and about 25 feet thick; the middle 

 of light-coloured sands, more than 12 feet thick, and with a thin bed 

 of pale bluish-grey clay, which, on being split along the lines of 

 lamination, often discloses impressions of leaves ; and the lowermost, 

 known as the "bottom-bed," about 12 feet thick, and consisting of 

 dark bluish-grey laminated clay, with green sand, flint pebbles, 

 sharks' teeth, oyster shells, and rare impressions of smaller shells, 

 besides the remains of microscopic animals, found by Professor 



^ Remarks on the Section at Shaw Clay Pit, and its relation to the Geology of the 

 District. A field-lecture given by W. Whitaker, B.A., F.G.S.y of the Geolgical 

 Survey. 



