36 Revieias — Geology of Colonsay and Oronsay. 



(G. W. L.) appended to his work happen to coincide with those of 

 another member of the Survey, Mr. Lamplugh. In regard to the 

 marine beds Dr. Lee points out that " Similarity of conditions induced 

 a similarity in the nature of the fauna". Thus certain abundantly 

 represented species disappear more or less suddenly, and then reappear 

 at a higher horizon, or in other cases vanish altogether so far as this 

 region is concerned. Changes in the position of the shore-line, or of 

 the rivers and marine currents, are justly considered to have influenced 

 the distribution of many organisms. 



The Igneous rocks include the Carboniferoiis lava-flows of the 

 Campsie Fells and Kilpatrick Hills on the north, and those of the 

 Cathkin Hills in the south. Descriptions are also given of various 

 volcanic vents, dj'kes, sills, etc. 



The general structure of the ground is described in a separate 

 chapter, and illustrated by a longitudinal section on the colour-printed 

 map, and by other sections in the text ; the faults also are described, 

 some having throws of about 300 fathoms. 



No attempt is made to give a complete account of the glaciation of 

 the area, or to describe in detail the Pleistocene deposits of the Clyde 

 Valley. The pre-Glacial topography of Glasgow and its immediate 

 neighbourhood is shown on a colour-printed map, depicting the land 

 as it stood at least 300 feet above present level. A. depression of the 

 area almost to present level then took place, accompanied by silting 

 up of valleys. Afterwards came the advance of the great ice-sheet, 

 from the north and north-west, the deposition of boulder-clay, and 

 the formation of drumlins, etc. The retreat of the ice was followed 

 (1) by the accumulation of the 100 foot beach- deposits with sub-Arctic 

 fauna, (2) by elevation and the formation of the 50 foot beach, and 

 (3) after other changes, of the 25 foot beach. The present physical 

 features and river-systems are described, and reference is made to 

 the influence of geography and geology on the rise and progress of 

 Glasgow. 



A chapter on Economic Geology, illustrated with figures of micro- 

 slides of rocks, gives abundant practical information relating to the 

 products of the Carboniferous rocks as before mentioned, with 

 particulars of Lime and Cement, Sands, Brick-clays, Paving-setts, 

 Road-metal, and Building-stones. The Building-stones are mostly 

 Carboniferous sandstone, but it is noted that Portland Stone has been 

 introduced. The subject of Water Supply is also dealt with, Glasgow 

 receiving water from Loch Katrine, 34 miles distant. Two wells 

 over 1,000 feet deep are mentioned, one of them yielding highly 

 saline water. 



2. The Geology of Colonsay and Oronsay, with part of the Ross 

 OF Mull. By E. H. Cunningham Craig, W. B. Wright, and 

 E. B. Bailey ; with notes by C. T. Clough and J. S. Elett. 8vo ; 

 pp. viii, 109, with 21 text-illustrations and 6 plates. 1911. Price 

 2s. %d. 



IT is perhaps unfortunate that the colour-printed map Sheet 35 

 (price 2s. 6^/.), of which this memoir is descriptive, contains no 

 part of Oronsay and not quite the whole of Colonsay. The missing 



