1867.] Geology and Palaeontology. 121 



% 

 of the valley-gravels of the Somine, the Ouse, and other rivers ; but 

 whether this docility has resulted from supineness or conviction we 

 cannot undertake to pronounce. Mr. Tylor, however, seems to 

 think that this state of things has lasted long enough, and in a 

 paper " Upon the Interval of Time which has passed between the 

 Formation of the Upper and Lower Valley-gravels of part of 

 England and France," he endeavours to show that the value of this 

 interval is nothing, and that the two sets of gravels are of the same 

 age. He explains and illustrates this view by stating his belief, 

 that the valleys themselves are of very ancient date, that subsequent 

 to their formation they were entirely filled with gravel, and that 

 more recently still the valleys have been re-excavated, leaving at 

 different heights patches of gravel which have escaped being washed 

 away. Mr. Tylor endeavours to explain the history of the valley 

 of the Somme on this supposition, by reference to the valleys of 

 Devonshire, just as Fluellin argued, " there is a river in Macedon ; 

 and there is also, moreover, a river at Monmouth" .... "and 

 there is sahnons in both." % 



The tendency of geological opinion on the subject of metamor- 

 phism has of late years been in favour of ascribing that phenomenon 

 to hydrothermal action ; but for the evidence in support of this theory, 

 geologists are almost entirely indebted to chemists and mineral- 

 ogists, the geological data in its favour being very scanty, and more 

 or less vague. We have now, however, to chronicle the publication 

 of a most important paper by Mr. J. Geikie, " On the Metamorphic 

 Lower Silurian Kocks of Carrick, Ayrshire," which contains a 

 generalized description of certain felspathic, dioritic, serpentinous, 

 and calcareous rocks, treated with a view of ascertaining what evi- 

 dence they may yield bearing on the cause of their metamorphism ; 

 for it is shown that these are all metamorphic, not igneous, rocks in 

 this region. In Mr. Greikie's own opinion, the details seem to 

 prove : — " (1) That the strata owe their metamorphism to hydro- 

 thermal action. (2) That the varying mineralogical . character of 

 the rocks is due principally to original differences of chemical com- 

 position, and not to infiltration of foreign matter at the time of 

 metamorphism. (3) That the highly alkaline portions of the strata 

 have been most susceptible of change. (4) That in beds having 

 the same composition, but exhibiting various degrees of alteration, 

 the intensity of the metamorphism has been in direct proportion 

 to the amount of water passing through the strata. (5) That in 

 some places the rocks have been reduced to a softened or pasty 

 condition." 



A paper " On the Structure of the Ked Crag," by that veteran 

 palaeontologist, Mr. S. V.Wood, sen., contains an entirely new view 

 (so far as we are aware) of the succession of life in those deposits 

 which are grouped under the name of Red Crag. No man is so 



