ON SOME IT^ATEAU DEPOSITS AT KELSTEAI) AND STEIiHINO. 1 35 



in the Plateau loams, a general description of which has already 

 been quoted ("roni the Survey Memoir. 



At Causeway End, Felstead, three-quarters of a mile S.S.E. of 

 church (marked erroneously on the old one-inch map as " Cobbler's 

 Creen '"), a loam of this description has been worked for many 

 years for bricks. It is over eight feet thick in one place, and it 

 everywhere rests on l^oulder Clay. Some curious facts have come 

 out in the working of this deposit. The entombed flints are nearly 

 all broken and, after the fracture occurred, they have at times sunk 

 to the bottom of the loam. At other times, after the fracture, the 

 pieces have separated laterally, sometimes as much as three inches 

 of loam intervening, and those corresponding pieces may now be 

 brought together and fitted again. Moreover, every piece has, since 

 its fracture, been coated with a brownish-yellow deposit. A grada- 

 tion in the character of the loam is also discernible, it becomin<r 

 stronger in proportion to its approach to the Boulder Clay. Bricks 

 made from the upper portion of the loam (but not so near to the 

 surface as to be affected by modern weathering) cleave with facility. 

 Those from the lower portion, in spite of much artificial working of 

 the clay, are much more refractory. 



At Great Baling Gravel Pit (near the church) a similar loam 

 occurs, having some of these peculiarities, and, in addition, nodules 

 of Boulder Clay retaining their chalk are enveloped in the mass. 

 I'undamentally these loams appear to differ only from Boulder Clay 

 in the angular character of their flints, and in the almost or complete 

 absence of chalk; a resultwhich may be brought about by weathering 

 alone, and that this was the agency there seems to be good evidence. 



The cleavage of the rocks, and their juxtaposition in the loam 

 points to the exertion of molecular forces such as those brought 

 into play by the action of frost and thaw. Their position alone 

 testifies to the changes having been made in place. That chemical 

 agencies, giving rise to the yellow coating of the flint fragments, have 

 been at work the following instance will show. A flint was found 

 which had been broken into two pieces, which, although still in contact, 

 had slid laterally. These were afterwards joined together by a siliceous 

 cement which could only have been the result of chemical agencies. 



The fracture of the flints by frost is easily explicable to those 

 conversant with the fragile character of recently dug flints. They 

 are then full of quarry water, upon which the least frost acts. The 

 behaviour of soils under the action of frost and thaw is familiar to 



