476 Revietvs — Davis' and Lees' Geology, etc., of W. Yorkshire. 



to infer that the beds doubtfully classed as Devonian are certain 

 " red conglomerates " at the base of tlie Mountain Limestone, and 

 resting in hollows in the Silurian slates below ; at all events they 

 have a chapter to themselves. No fossils have been found in these 

 conglomerates " except such as are inclosed in the Silurian stones 

 it contains," 



The Perraians are treated of separately, and the existence of a 

 considerable break at this locality between them and the Coal- 

 measures insisted on, though their relation to the overlying Trias is 

 not mentioned. The red and purplish-red Plumpton Grits, hitherto 

 classed as Permian, are now, on the authority of the Geological 

 Surveyors, relegated to the Millstone Grit series, which is here imme- 

 diately ovei'lain by the Permian beds. 



Arrived at the Trias, we become aware of a slight change in the 

 method of treating the component beds, for both the list and de- 

 scription are in descending order. In the preceding formation the 

 list was in descending order, the description in ascending; whilst in 

 the Silurian and Carboniferous both lists and descriptions are in 

 ascending order. Variety, though charming, may prove sometimes, 

 as in the present instance, rather confusing. 



The fashionable " Glacial Period," which follows on the Trias, is 

 fully dealt with, and we read of a " great glacier " 1500 to 2000 

 feet thick, and of another "eight miles broad and at least 700 or 

 800 feet deep." These ice-giants do not appear to have troubled 

 themselves about excavating lake-basins ; but merely to have passed 

 their time in scratching the rocks over which they passed, and in 

 transporting huge rock fragments from place to place. Some re- 

 markable examples of erratic blocks of Silurian age that have been 

 stranded on the Mountain Limestone of Norbar, near Clapham, are 

 figured on plates xiv. and xv. The Drift deposits are very irre- 

 gular in their mode of occurrence ; thus, "on the synclinal south-west 

 of Carlton, drift is exposed at Park Head Quarry at a height of 

 1050 feet ; other parts of the same synclinal at a height of not 

 more than 600 feet are devoid of drift. As a rule the thickest 

 deposits are in the valleys and on low grounds ; they are thinner on 

 the hill-sides, and either very thin or absent on the grit and lime- 

 stone ridges which usually form the summits of the highest hills." 



With the succeeding Post-Glacial beds the first part closes, and 

 we start over the ground afresh with an eye to its physical geo- 

 graphy and topographical botany, especiallj'^ the latter. Omitting 

 the long list of botanical names, it is, from its very nature, far more 

 " readable " than the foregoing. 



The plates, which bring up the rear, are diagrammatic rather than 

 elaborate, and are well suited to the purposes for which they are in- 

 tended. One can only wish that a few more had been added giving 

 views illustrative of the different landscape effects produced by the 

 several formations, as in the Survey publications. The maps, stowed 

 away in pockets in either cover, are on a scale of 4in. to the mile, 

 and carefully finished. The geological one will certainly, as Mr. 

 Davis hopes, " be of service to practical geologists, the more so that 



