EE VIEWS. 



39 



For those who want to get a fair running knowledge of geology with the 

 least amount of trouble, Mr. Jukes's book will be just the thing. "We 

 think highly of Mr. Jukes's ability, and we wish it had been a great work, 

 or a small work on some special topic, — something, in short, beyond an ele- 

 mentary treatise going all over the old ground, — that we might have spoken 

 as much kind praise as we have every pre-existing desire to give to any 

 meritorious labours that emanate from any of the Survey men. 



The Flora of Marlborough. By T. H. Preston. 



With Mr. Preston's brochure as a Flora we may have, seemingly, little 

 to do, but there is an important connection between the plants of a district 

 and the soil on w r hich they grow. This soil may not be necessarily the 

 debris or the resultant of the weathering and atmospheric degradation of the 

 true geological strata of the district, and indeed it may be, as it very often 

 is, formed from a superficial covering of the drifted and over-covering 

 materials of a later and long subsequent age to that of the underlying 

 rocks to which the main outlines of the physical geography are due.. 

 Botanists have perceived this relationship, and although they must neces- 

 sarily regard it in a different light, we find that in local, and even in 

 general Floras, considerable attention is now paid to the geological features 

 of the district or country under botanical description. In this manner 

 the geology of Marlborough is set before us in the little volume we are 

 reviewing, before even the flow r ers of the region are recorded. This survey 

 of the botanist is especially useful in its w r ay to the practical geologist, 

 because it investigates the superficial covering of the earth in a manner in 

 which he would be little likely to do, and yet not the less important, as by 

 it we obtain a knowledge of the workings of external agencies upon the 

 ground that produces vegetation. In the neighbourhood of Marlborough, 

 we are told that the surface for miles round, and to a great depth, has been 

 entirely formed by these external agencies ; the Kennet, as an example, we 

 are told, has at Lockeridge, only four miles from its source, filled up one 

 of its former courses, and made a new track for itself through the marshy 

 ground. On the northern side of the Kennet, the country consists almost 

 entirely of Upper Chalk, with a few outlying patches of red clay on the 

 tops of the hills. In a wood to the north of Mildenhall, there occurs a 

 red stratified clay, more than tw r elve feet in thickness. About four miles 

 east of Marlborough, on the ridge by the Kennet, there is a vertical fault 

 running nearly north and south ; the western side being occupied by hori- 

 zontal layers of Upper Chalk with flints, and the eastern by a reddish- 

 brown sand, containing flint pebbles up to a pound in weight. Between 

 Graham Hill and Martinsell the chalk is stated to be covered by boulder- 

 clay, which is said also to extend westward as far as Clatford Bottom, and 

 probably to form the subsoil of the greater part of the west woods, and on 

 the eastward runs into Savernake Forest. In the valley to the south of 

 Granham Hill there is a strip of light-coloured sandy clay overlying the 

 chalk, and to the south of this what is called " a mottled red boulder-clay," 

 containing large masses of flint-nodules and sandstone boulders. Near the 

 top of the chalk slope at the north-west corner of the forest there is a 

 trough-like hollow in the chalk, five-and-twenty feet wide and eight feet deep, 

 fitted up with layers of red clay with large broken flints and chalk rubble, 

 and thickly studded with "two kinds of fossil shells of the genus Helix, 

 which very much resemble 11. occlusa, and a smaller species, 11. d' Urbani, 

 some of which are beautifully marked. This hollow may have been the 



