516 Reviews—The Leicestershire and Derbyshire Ooalfield. 
In the Swansea area the Coal-measures attain a greater thickness 
than is at present known in any other part of the coalfield, about 
7,000 feet. In this great series is included about 1,050 feet of the 
highest measures. Seams are worked in all three divisions of the 
series. 
A notable discovery by Logan was that of pebbles of coal im the 
Pennant Grit near Swansea. We fail to find any particular reference 
to this, although incidentally the occurrence of pebbles of coal is 
mentioned. 
In the Swansea map are included the eastern portions of the 
picturesque region of Gower, where Silurian rocks were discovered 
by Mr. Tiddeman. There are many other features of great interest 
in that promontory, in the lithological characters of the Lower 
Carboniferous rocks, and in the disturbances to which they have 
been subjected. The dolomitisation of the limestone, to which special 
attention has been given by Dr. Pollard and Mr. Dixon, is regarded 
as for the most part contemporaneous, the alteration having taken 
place so shortly after deposition that the magnesian salts were 
probably derived from the Carboniferous sea. Again, the recognition 
of radiolarian cherts in the Upper Limestone Shales confirms De la 
Beche’s correlation of the strata with the Coddon Hill Beds of North 
Devon. 
The Glacial Drifts in the areas of Ammanford and Swansea indicate 
the former great development of ice in regions further north, whence 
there was a southerly movement, the ice overriding and glaciating all 
except the higher hills. Important, too, is the evidence gathered by 
Mr. Tiddeman that this glaciation is later than the Raised Beach of 
Gower and the Cave accumulations with Pleistocene mammalia. 
II.—Tuet Grotogy oF THe LeicestersHireE anp Soura DersysHiRE 
Coatrietp. By C. Fox-Srraneways, F.G.S.; with Paleontological 
Notes and List of Fossils by A. R. Horwoop. 8vo; pp. 373, with 
colour-printed geological map, 6 plates, and 12 text-figures. 
Cloth; price 6s. 
N 1860 a concise memoir by Edward Hull on ‘‘ The Geology of the 
Leicestershire Coalfield and of the Country around Ashby-de-la- 
Zouch ” was issued by the Geological Survey. It occupied 70 pages. 
of print, was accompanied by a neatly coloured geological map. 
engraved by Lowry, and was sold at the price of 3s. It was a handy 
memoir, well adapted for the pocket of anyone who was making: 
a personal study of the area. Now after a lapse of nearly fifty years. 
the results of a far more detailed survey, carried out on the six-inch 
scale entirely by Mr. Fox-Strangways, have been published in the 
memoir before us. Although the paper and printing of the present 
work do not equal that of the former one (see, for instance, the figure. 
of Outcrop of the four-foot coal at Blackfordby), yet when we compare 
the bulk of this work with its predecessor—the number of printed 
pages, including much tabular matter, the large’ folding plates of 
sections, and the cloth case—a comparison of the respective prices is. 
wholly in favour of the new volume. 
