510 H. W. Monckton — Gravel-Flats of Surrey and Berks. 



In Pearson's " Story of Ladysmith," p. 108, it is stated that in 

 ascending Gun Hill, to capture the Boer guns, the soldiers found 

 that the boulders, rounded and worn by the storms of ages, were 

 slippery to tread on, and occasionally the foot would become wedged 

 between them. 



The photograph marked, No. 3, gives a general view of a ridge, 

 on the upper level, near the hospital, from which loose blocks have 

 fallen to the slopes below. The upper portion of the ridge consists 

 of a fine-grained sandstone ( ? Upper Karoo beds). 



On the hill-tops of the district the igneous masses show some flat 

 surfaces, and a further effect of weathering is seen in numerous 

 shallow depressions more or less circular, with a diameter of an inch 

 and a half to two inches. 



About half a mile in a north-westerly direction from this hospital 

 some military trenches have been cut across the summit of a low 

 hill. The stones there exposed are similar to the surface-rock of 

 the country (dolerite or diabase) elsewhere ; but they vary in size 

 from a mere flake to a ton in weight, and are cemented together 

 by a yellow ferruginous sandy matrix, and each separate stone is 

 encrusted by a coating of the same firmly adherent. The pieces 

 have mostly fairly angular edges without any rounded or water- worn 

 aspect. 



It is very probable that this red matrix in which the diabase is 

 imbedded is the result of decomposition. If so, these stones of hard 

 crystalline rock, thinning out to thin sheets (such as the specimens 

 sent), appear to have been either intrusive or overflowing lavas. 



Mr. Fred. Chapman, A.L.S., who has kindly examined the 

 specimens sent home, states that the so-called diabase is an altered 

 augite-andesite (porphyrite). The specks of magnetite scattered 

 throughout have decomposed and given rise to the vivid orange-red 

 or brick-red exterior. The weathering action has, no doubt, been 

 accentuated by extremes of temperature. 



VII. — On the Oeigin of the Gkavel-Flats of Sukbey and 



Beekshire.i 

 By Horace Woollaston Monckton, F.L.S., V.P.G.S. 



IN the south-east of England considerable tracts are covered by 

 sheets or patches of gravel. It is mainly composed of flints 

 from the Chalk, has a thickness of, say, from 6 to 20 feet, is 

 generally stratified, and rests upon an uneven surface of the older 

 strata. The top is nearly always flat and inclined at a low angle. 



These sheets of gravel lie at various levels : thus, at Csesar's Camp, 

 Aldershot, there is a large gravel-covered flat the highest part of 

 which is 600 feet above the sea. A little to the north-east there 

 is another flat, named the Fox Hills, at a level of 360-390 feet, and 

 a few miles to the north there are Hartford Bridge Flats, which lie 

 330 feet above the sea. (These are in Sheets 284 and 285 of the 

 new series one-inch ordnance map.) 



1 Bead before the British Association, Section C (Geology), Glasgo-s7, Sept., 1901. 



