PROGRESS IN THE STUDY OF ANCIENT SEDIMENTS. 5 



which often contain a fauna similar to that of the matrix 

 in which the pebbles are included. These chiefly occur 

 in the case of limestone. The author observes that "the 

 history of Appalachian sedimentation and mountain-building 

 proves that a more or less constant movement was taking 

 place from Algonkian 1 time to the close of the Palaeozoic. 

 This movement was at times greatly prolonged and resulted 

 in marked topographic features. More frequently the 

 minor movements produced local effects, and some of 

 them resulted in the formation of the conglomerates de- 

 scribed." 



These papers have been noticed at some length because 

 they appear to confirm results obtained by geologists in the 

 Old World that orogenetic movements occurred during much 

 longer periods of time than was once supposed, though 

 each great uplift was not necessarily the result of con- 

 tinuous movement. At the same time it is not clear that 

 all the conglomerates described in these papers are true 

 deposits. The writer of this article has had frequent 

 occasion of late years to study friction-breccias and friction- 

 conglomerates, and he finds that the latter are specially 

 prone to occur in limestones. In such cases the occurrence 

 of a similar fauna in the matrix and the pebbles would be 

 readily explicable. The statement of one of the above 

 authors that the meaning of one of the conglomerates " is 

 obscure " encourages one to suggest the probability of the 

 occurrence of friction-conglomerates amongst the highly 

 disturbed rocks of the region described, for they are far 

 from rare amongst the disturbed regions of Europe, and 

 frequently simulate conglomerates of deposition with ex- 

 traordinary fidelity. 



A paper by M. Marcel Bertrand (5) on the Alps is 

 chiefly devoted to the foldings and their effects, but contains 

 information about the Alpine Carboniferous rocks. Another 

 Alpine paper (6) treats of a district which has previously 

 been described at considerable length by Lory ; in this 

 paper also the systems of folds are discussed in detail. A 



1 Late Precambrian. 



