Reviews — Dr. W. Gibson — The Concealed Coal-field. 373 



silted up. Westwards the marshlands bordering the rivers, as near 

 Lewes, afford similar evidence, while Southampton Water, the Solent, 

 and Spithead, with the adjacent harbours, are likewise submerged 

 valleys. In Cornwall and on the Devon borders Plymouth Sound is 

 held to represent a basin once filled with Tertiaiy and Secondary 

 deposits and subsequently cleared out, the rocky basin having been in 

 part silted up again. The stream-tin deposits belong to a late stage 

 of the Pleistocene period, and were succeeded by the growth of trees 

 and of sundry layers belonging to submerged forests. With regard 

 to the vexed question of the isolation of St. Michael's Mount, the 

 author is of opinion that " as far as can be calculated from its known 

 rate of encroachment, the sea cannot have reached the Mount till long 

 after the Roman period ". 



In a final chapter the author gives a summary of his conclusions, 

 and points out that his main object has been to suggest directions for 

 further research on a much-neglected subject. All the accumulations 

 of the submerged forests appear to be of Neolithic age. The fauna 

 and flora consist of living British species, with a few mammals since 

 exterminated by man. 



The account which we have given of this volume will indicate how 

 carefully the author has considered all aspects of his subject with 

 regard to both fact and opinion. At the same time it may be said 

 that opinions which will be regarded by some geologists as debatable, 

 are not wanting. 



In a bibliography the author gives the titles of papers specially 

 bearing on the matters discussed, but as he does not attempt to deal 

 with or even enumerate the many submerged forests that have been 

 described, there is no mention of some geologists like Pengelly, 

 TJssher, and Codrington, who have published important papers on 

 the subject. 



II. — Geological Stjrvet Memoir. 

 The Concealed Coal-field of Yorkshire and Nottinghamshire. 

 By Walcot Gibson, D.Sc. 8vo; pp. vi, 122, with 3 plates and 

 5 text-illustrations. London: printedfor His Majesty's Stationery 

 Office, 1913. Price \s. 6d. 



THIS is an eminently practical memoir, dealing as it does with the 

 underground extension of the Nottinghamshire, Derbyshire, and 

 Yorkshire Coal-fields, sometimes grouped as the Great Yorkshire 

 Coal-field. The exposed areas of Coal-measures in Nottingham border 

 the Erewash valley in the western part of the county ; in Derby they 

 border the western side of that river-valley, extending through 

 Chesterfield to the northern end of the county ; thence in Yorkshire 

 the strata are exposed from Sheffield to Leeds. The Magnesian 

 Limestone and other Permian beds cover the eastern portion of the 

 Coal-measures, succeeded by various members of the Trias and sundry 

 superficial deposits. Beneath the Permian and newer deposits 

 Coal-measures have been proved through the greater part of 

 Nottinghamshire, and northwards into the area now known as the 

 East Yorkshire Coal-field, which extends from Doncaster to Thorne 

 and Selby in the Yale of York. This area is shown on the map 



