472 Revieivs — Dr. L. Cayeux's Sedimentary Rocks. 



though these may well bo nothing more than the ' doggers,' or 

 •■ potlids,' so characteristic of calcareous sandstones. Mr. Winwood 

 believes that " the so-called foreign boulder " in the Gloucester 

 Museum evidently came from the ' Harford Sands.' 



So far, therefore, the evidences of glacial action in the Cotteswolds 

 do not rest on a very sure foundation. Yet the Severn Valley 

 separates that range from an area on the vv^est, where there are 

 clear evidences of local glaciation, as described in the Annual 

 Eeport of the Geological Survey for 1896. Portions of this 

 material find their way into the river bed and elsewhere as Drift 

 which has most probably been rearranged ; hence the so-called 

 Boulder-clay and Drift in the bed of the Severn. Once more, 

 then, in the cycle of geological time we perceive that our district 

 lies on the confines of two distinct sets of phenomena. West of 

 the Severn and north of the Bristol Channel the evidences of 

 considerable local glaciation are obvious, whilst this can hardly 

 be said of the Cotteswolds, the Mendips, or the Qaantocks. 



To the more recent geological history of our district it will bo 

 sufficient to allude in the briefest terms, when I remind you of the 

 paper by Mr. Strahan on the deposits at Barry Dock, and the still 

 later one by Mr. Codrington on the submerged rock valleys iu 

 South Wales, Devon, and Cornwall. Here we have important 

 testimony to certain moderate changes of level which have taken 

 place, and a picture is presented to us of the Bristol Channel as 

 a low-lying land - surface, with streams meandering through it. 

 Thus a depression of something like 60 feet appears to be the 

 most recent change which the geologist has to record in the estuary 

 of the Severn. 



la IE "V I E "W S. 



I. — Contribution a l'P^tude Mickographique des Terrains Sedi- 

 MENTAiRES. I. Etudo de quelques depots siliceux secondaires et 

 tertiaires du Bassin de Paris et de la Belgique. H. Craie du 

 Bassin de Paris. Par Ltjcien Cayeux, D. es Sc. 4to ; pp. 589, 

 pis. X, and 20 figures in the text. (Lille : Le Bigot Freres, 

 1897.) 



IN this elaborate work Dr. Cayeux gives the results of an extended 

 series of investigations into the minute structure of the sedi- 

 mentary rocks mainly of the Paris Basin, but including as well some 

 in the North of France and adjoining areas in Belgium. The age of 

 the rocks treated of ranges from the Jurassic to the Eocene, but the 

 greater number belong to the Cretaceous Series, from the Albian to 

 the Senonian, or, in English terms, from the Gault to the Upper 

 Chalk with Belemnitella mucronata. The author's aim has been, by 

 a close study of the present characters of the deposits, to ascertain 

 their natural history, and to trace the efiects of the various 

 mechanical, chemical, and physiological agencies to which they 



