BROWNE ; GEOLOGY OF HIGH WYCOMBE. 



267 



great division of the geologist includes five important groups — the Cretaceous, 

 Wealden, Oolite, Lias, and Trias. To the first of these series belong the 

 chalk hills which form the principal feature of the country around Wycombe. 

 If we take a short trip into the country, we find at Lane End a good repre- 

 sentative of one of the Tertiary divisions. N"ear the surface, still more at a 

 little depth below the surface, we find yellow and dark clays alternating 

 with yellow and brown sands, with thin laminae of white clay intermixed. 

 If we compare the fossils of this place with those that are collected from the 

 Reading and Woolwich beds, we shall perceive that they are generically and 

 specifically the same. Hence we judge that this formation is of the same 

 geological age, and must be ranked amongst the strata that compose the 

 Tertiary division. In the road to Beaconsfield, on Flackwell Heath, and 

 more largely developed at Cookham, we have gravel beds. These in the 

 language of the geologist, are called drift. There are two series of gravels — 

 the upper and lower level gravels. These beds consist of clays mixed up 

 with flints more or less broken, which have accumulated in these localities 

 by the action of floods, and perhaps been driven or carried along by large 

 icebergs or glaciers. On some of the commons in our neighbourhood 

 there are large Boulders. These are composed of granular siliceous sandstone. 

 Their nature and origin were long a mystery, until the geologist threw some 

 little light upon them. We have reason to believe that these great blocks of 

 stone are mere wanderers which have been broken off from their parent rocks 

 and have been carried along and deposited where we find them, by immense 

 masses of ice called glaciers. The grinding and grooving actions of these 

 icebergs on the rocks over which they have passed can still be seen by the 

 experienced eye of the geologist. These Gravels and large boulder rocks 

 belong to wl^t is called by some geologists the Quarternary division, by 

 others the Post-pleiocene division, These formations are closely connected 

 with the recent history of our planet, aud perhaps ^may be identical with the 

 period of man's history. In these gravels we discover the remains of large 

 Mammalian bones. Amongst tham are the bones of the Irish elk, rhinoceros, 

 cave bear, but especially the elephant. Indeed the species of fossil elephants 

 outnumber the species of recent elephants that now inhabit our world. The 

 uppermost beds of the great Secondary division are called the Cetaceous 

 group. But this group is subject to yet further subdivision into eight dis- 

 tinct formations, viz, the Maestricht beds and Faxoe Limestones, the Soft 

 Chalk with flints, the Chalk Rock, the Lower or Hard Chalk, the Chalk 

 Marl, the Upper Green Sand, the Gault, and the Lower Green Sand. The 



