Geology and Mineralogy . 391 



based upon the hypothesis that the sediments were accumulated 

 in a fresh or brackish water estuary, or possibly a lake in close 

 connection with the sea, entirely overlooking the suggestion of 

 Davis, put l'orth in 189V, that,— " The pre-Triassic peneplain 

 might have been warped so as to alter the action of the quiescent 

 old rivers that had before flowed across it, yet not to drown or to 

 pond them. Such a change would set the streams to eroding in 

 their steepened courses, and to depositing where their load 

 increased above their ability of transportation. As with marine 

 or lacustrine deposits, the thickness of the strata thus produced 

 would depend upon the duration of the opportunity for their 

 deposition. A progressive warping, always raising the eroded 

 districts and depressing the area of deposition, would in any of 

 these cases afford the condition for accumulating strata of great 

 total thickness. The heavy accumulations of river-borne waste 

 on the broad plains of California, of the Po, or of the Indo- 

 Gangetic depression all agree in testifying that rivers may form 

 extensive stratified deposits, and that the deposits may be fine as 

 well as coarse. They are characteristically cross-bedded and 

 variable, and they may frequently contain rain-pitted or sun- 

 cracked layers." 



" In contrast to marine deposits, Penck has suggested the 

 name 'continental' for deposits formed on land areas, whether 

 in lakes, by rivers, by winds, under the creeping action of waste 

 slopes, or under all these conditions combined. This term seems 

 more applicable than any other to the Triassic deposits of Con- 

 necticut. It withdraws them from necessary association with a 

 marine origin, for which there is no sufficient evidence, and at 

 the same time it avoids what to-day is an impossible task — that 

 of assigning a particular origin to one or another member of the 

 formation. A continental origin of the formation would accord 

 with Dana's conclusion that the Triassic beds ' are either fresh- 

 water or brackish-water deposits.' There may possibly be 

 included an occasional marine deposit along the axis of the 

 depressed trough, for at one time or another a faster movement 

 of depression than usual may have outstripped deposition and 

 thus caused submergence ; but, in the absence of marine fossils, 

 the burden of proof must lie on those who directly maintain the 

 occurrence of marine deposits."* 



The suggestion of Davis as to the possible fluviatile and sub- 

 serial origin, taken in connection with the foot-prints, rain-prints 

 and mud-cracks which characterize so much of the formation, is 

 raised to the level of the only probable view for such portions of 

 the Triassic if the conclusions in an article by the reviewer on 

 " Mud-Cracks as a Criterion of Continental Sedimentation "f be 



*W. M. Davis, The Triassic Formation of Connecticut. 18th Ann. Kept. 

 TJ. S. Geol. Surv., 1897, Pt. II, pp. 32, 33. 



f Joseph Barrell, Studies for Students. Kelative Geological Importance of 

 Continental, Littoral, and Marine Sedimentation. Journal of Geology, vol. 

 xiT, 1906, Pt. Ill, pp. 524-568. 



