512 Notices of Memoirs — 



Geology of tlie Kingsclere Valley," with various illustrative maps 

 and diagrams placed around him on the sward. He prefaced his 

 observations with an apology for having to deal with such a large 

 subject in so limited a time, and for the difficulty of treating in a 

 popular way such complicated geological facts as were concerned in 

 the origin and history of the beautiful valley lying at the feet of his 

 audience. He would take for granted that all pi'esent were acquainted 

 to some extent with geology ; that they knew that chalk is not always 

 what it seems ; that it is made up of innumerable microscopic shells, 

 and is subject to change ; that the valleys were due to causes of 

 which even geologists had not in all cases a very clear idea ; that 

 the hills were not masses of earth or stone placed, as it were artifi- 

 cially, upon a given horizontal surface, but were intimately connected 

 with the internal structure of the earth, and that their constituent 

 strata could be traced out as massive stony sheets or layers, stretch- 

 ing away, not only through Berks and Hants, but through England 

 and Europe, and other parts of the world. The hills and valleys 

 spread out before them were not created as such. There was a time 

 when this valley did not exist, but its place was occupied by a great 

 solid arching of the Chalk and other strata, continued on all sides as 

 a vast plateau, gradually rising from the sea. The broken upper 

 courses of this great arch, or elliptical dome, two miles by six in its 

 chief diameters, were washed away, together with the softer mate- 

 rials, by sea and rain ; and the broad undulating hollows and sloping 

 sides were left that now form the Kingsclere "valley of elevation," 

 so well described by Buckland many years ago. It is of a long 

 triangular shape, pinched in at the sides ; and it constitutes what 

 geologists term an "inlier" of some of the strata below the Chalk. 

 The containing hills, or scarped edges of the broken Chalk, stand 

 high up above the floor of the valley, because of their relative hardness. 

 Their white calcareous substance, though soft as a rock, is homo- 

 geneous and tough, especially in their lower tiers or courses, where 

 the greyish Chalk-marl (or Malm-rock) is tougher still, and projects 

 around the valley as low, smooth, rounded hills and level benches, 

 too tough for the natural growth of trees, but yielding rich crops to 

 the plough and harrow. Of this formation, Beacon Hill (just visited 

 by the Field Club) is a part, where the more forcible curvature of 

 the strata, in the chief focus of elevation, raised this Lower Chalk 

 higher than elsewhere. The central portion of the valley is made 

 up of a different substance, which is called the " Greensand," or 

 " Upper Greensand." It is a calcareous or chalky substance, with a 

 considerable quantity of sand in its constitution. Some of this sand 

 is green, being fragments and minute concretions of a mineral called 

 glauconite. In Wiltshire the green sand predominates, hence these 

 strata got the name of " Greensand." Here and there this rock is 

 hardened into a "rag-stone" by the infiltration of silex ; just as some 

 of the Chalk is frequently changed into lumps of flint. The Green- 

 sand, being more friable than the Chalk or the Chalk-marl, and of un- 

 equal texture, has rotted away at the surface into a rich loam, bear- 

 ing trees and copses, which still abound in the valley round about 

 Burghclere and Sydmonton ; and it well repays the farmer's toil. 



