352 J. BARRELL FLUVIATILE ORIGIN OF OLD RED SANDSTONE 



those now found m the Great Valley of California. There was, however, 

 no presentation of detailed argument. Since then Grabau and the pres- 

 ent writer have independently and repeatedly written on the part which 

 the rivers of later Paleozoic time have played in continental deposition, 

 dealing chiefly with the rivers flowing westward from Appalachia. The 

 arguments for them apply with variations to the British deposits also. 

 Grabau studied the latter some years since, in the field, and has stated 

 that he is in full agreement with the conclusions of this paper in regard 

 to the dominantly fluviatile character of the sediments. Approaching 

 the subject from another side, Doctor O'Connell has written an extensive 

 paper, entitled "The Habitat of the Eurypterida," to be published as one 

 number of the Bulletin of the Buffalo Society of Natural Sciences. She 

 has treated the subject of the Old Eed Sandstone at some length, pre- 

 dominantly, though not exclusively, from the standpoint of the faunal 

 evidences. The conclusion is reached in her paper that the eurypterids 

 were preeminently a fluviatile fauna, and their associations in the Old 

 Red Sandstone show that the latter is dominantly fluviatile. This is a 

 supplemental line of evidence, and she states as a conclusion : 



"I am convinced that the detailed study of the geological and geographical 

 distribution of the eurypterids (and I think the fishes, also) will do more than 

 anything else to prove that they lived in the rivers, and that many peculiar 

 deposits will be easily explained as of floodplain or delta origin when the 

 importance of fluviatile deposition is once realized." 8 



In the Textbook of Geology by Pirsson and Schuchert, published 1915, 

 the view is adopted by Schuchert that the Old Red of Scotland is probably 

 wholly continental. The opinions of Goodchild and Walther are quoted, 

 but the basins, following the British custom, are still spoken of as lakes ; 

 and it is stated # that Lake Orcadie may have extended as an estuary north- 

 east to Christiania, in southern Norway, and possibly even to Petrograd, 

 in Russia. The south Irish deposits are regarded by Schuchert as 

 marine.* 



Criteria as to Modes of Origin of Sediments ° 



It is evident from the preceding review of opinions that a sound con- 

 clusion regarding the geography of the British Isles during the Devonian 

 period depends not so much on the accumulation of new facts of observa- 



8 Personal communication. 

 * Pages 715-717, 1915. 



9 This topic is essentially a summary of such arguments as bear on the present prob- 

 lem from articles published by the writer in the Journal of Geology and Bulletin of the 

 Geological Society of America. If this article dealt only with American geology, a very 

 brief restatement of these criteria would doubtless suffice ; but as the subject in hand is 



