496 



to their survey and sections the coal plants of Bideford, so far 

 from constituting any anomaly, so far from affording any objection 

 to the doctrine that particular species of fossil plants are good tests 

 of the relative age of rocks, do in reality from the place which they 

 occupy, confirm that doctrine ; for the culmiferous rocks distinctly 

 overlie the so-called grauwacke, and are not referable to any of the 

 well defined and normal types, which compose the old Red Sand- 

 stone and Silurian System. 



I shall now pass on to the consideration of other memoirs on En- 

 glish Geology. The limestone which the Germans call muschelkalk, 

 and the numerous fossils which are pecuhar to it, have not yet been 

 detected in England in any part of that great series of beds which 

 intervene between the lias and the coal. In those parts of Germany 

 where it occurs, it divides the beds of red marl and sandstone which 

 occupy that great interval into two divisions, the upper of which 

 is called keuper, and the lower hunter sandstein. In the absence 

 of the muschelkalk in this country, it has been impossible for us 

 to separate our new red sandstone into two well defined masses ; 

 but Dr. Buckland considers that certain portions of the upper beds 

 in Warwickshire and elsewhere may be identified with the keuper 

 by their mineral character, and near Warwick by the remains of a 

 Saurian, which he believes to be of the genus Phytosaurus, a genus 

 characteristic of the keuper of W^irtemberg. 



An examination in the South-east of England of the strata usually 

 termed plastic clay, has led Mr. John Morris to offer several new, 

 and as they appear to me, judicious suggestions in regard to the 

 classification of these beds. It is well known that wherever the 

 tertiary strata are seen in immediate contact with the chalk, they 

 consist of alternations of sand, clay, and pebbles, and in some 

 few places a calcareous rock, — all these varying greatly in their 

 thickness, and in their order of succession in different places. 

 Mr. Morris divides those of Woolwich into two parts, and states 

 that the upper is characterized by a mixture of marine and fresh- 

 water shells, the freshwater genera being Cyrena, Neritina, Me- 

 lanopsis, and Planorbis. The lower division contains exclusively 

 marine shells. The author refers this intermixture to the in- 

 flux of a river into the sea, in which the London clay was formed. 

 Mr. Morris considers the Bognor strata, which rest immediately 



