138 Reports & Proceedings — Geological Society of London. 



"were produced by earthquake disturbances set up by movement along 

 •one of the north-north-west and south-south-east faults, and the 

 sediment on the sea-floor ran in and sealed them up. 



A. mineralogical examination of the Whitehaven Sandstone and 

 of the sandstone of the dykes shows that they have much in common, 

 notably in the types of heavy minerals. 



The sequence of events postulated supports the view of an 

 -unconformity at the base of the Whitehaven Sandstone. With 

 regard to dykes in other parts of the Coalfield which show contortion 

 in passing through the coal-seams, the author argues for their 

 formation before consolidation of the enclosing measures. 



2. January 22, 1919.— Mr. G. W. Lamplugh, F.R.S,, President, in 



the Chair. 

 The President announced that a Special General Meeting of the 

 Society would be held on Wednesday, March 26, 1919, at 6 p.m., to 

 consider the following Resolution of Council: " That it is desirable 

 to admit women as Fellows of the Society." 



The following communications were read : — ■ 



(1) "On the Occurrence of Extensive Deposits of High-level 

 Sands and Gravels resting upon the Chalk at Little Heath, near 

 Berkhamsted." By Charles Jesse Gilbert, F.G.S. 



In a pit recently opened at Little Heath Common on a plateau of 

 the Chiltern Hills, 550 feet above sea-level, the following section 

 has been developed : — 



Thickness in feet. 

 6. Surface soil with bleached flint-pebbles from the 



Beading Beds ..... about 2 



5. Pebbly clay and other Glacial deposits, varying 



from . . 

 4. Stratified loamy sand ...... 



3. Stratified coarse gravel ..... 



2. Dark clay, with black-coated unworn flints and 

 small well-rounded pebbles .... 



1. Chalk. 



The upper Glacial deposit is a pebbly clay. The pebbles, which 

 are nearly all bleached and highly waterworn, are derived from the 

 Beading Beds. The pebbles are almost always in a vertical position, 

 or highly inclined, some being crushed in situ. 



The clay matrix is tough and mottled, and the highly coloured 

 tints of the clay leave little room for doubt that it has been derived 

 from the upper part of the Beading Beds. 



The Chalk flints, which are scattered in such profusion over all 

 parts of the surrounding country, are almost entirely absent, while 

 the small pebbles of white quartz and lydite, so abundant in the 

 underlying gravel, are seldom met with. It seems probable that 

 the ice must have derived its materials from a distant area. The 

 deposit is very persistent, often cutting into and disturbing the beds 

 beneath. 



On the west side of the pit, underlying the pebbly clay, is a 

 •disturbed mass of Glacial sands and clay, of a very miscellaneous 



