E. M. Kindle — Criteria of Continental Deposits. 225 



Art. XXV. — Gross-bedding and Absence of Fossils Consid- 

 ered as Criteria of Continental Deposits ;* by Edward M. 

 Kindle. 



In recent years a marked inclination has developed in some 

 quarters to question the marine origin of certain formations 

 which have hitherto been classed as sea-laid deposits. The 

 writer heartily approves of the close scrutiny which some of 

 the earlier assumptions in this field are receiving. If, how- 

 ever, we are to make any permanent progress in this direction 

 it is highly important that the newer views on this subject 

 should themselves be something more than mere assumptions 

 or conclusions based upon false premises. In some cases before 

 the later opinions concerning the conditions of deposition can 

 be accepted it will be necessary to submit more satisfactory 

 criteria for discriminating nonmarine from marine deposits 

 than those on which some authors appear to rely chiefly. If 

 one may judge from the character of the evidence used in 

 some recent papers for establishing the continental origin of 

 formations, there is urgent need of clarifying our ideas con- 

 cerning the criteria by which such deposits may be recog- 

 nized. This note is intended to assist in this process by 

 pointing out the fact that some of these criteria will not bear 

 critical examination. 



While some authors have furnished satisfactory evidence 

 of the continental origin of certain deposits, e. g., the Triassic 

 sandstone of Connecticut, others have not taken the trouble to 

 tell us what criteria they use for discriminating continental 

 from marine deposits, giving instead of evidence some such 

 statement as " we have expressed the opinion that the sand- 

 stone was a continental deposit. "f Prof. A. W. Grabau, how- 

 ever, has been sufficiently explicit in indicating two of the 

 criteria which he considers available in such discrimination. 

 Tiie following quotation from Professor Grabau indicates the 

 manner in which the general absence of fossils and the pres- 

 ence of cross-bedding is used as evidence of the nonmarine 

 origin of beds which exhibit these features. In discussing the 

 age and origin of certain sandstones he states : 



" In fact, the general absence of fossils, the frequent cross- 

 bedding and other characters point rather to a continental origin 

 of a part, at least, of this basal series, the agents of deposition 

 being rivers or the wind. There is scarcely a geologist today 

 who is satisfied with the complacent explanation, current only a 



* Published with the permission of the Director of the TJ. S. Geological 

 Survey. 

 fBull. N. Y. State Mus., No. 145, p. 122, 1910. 



