256 ANNAL.^ NEW YORK ACADEMY OF SCIENCES 



SuMMAEY OP Papers 



Mr. Knight stated that the "red beds" consist principally of sand- 

 stone, arkoses and conglomerates, with smaller amounts of limestone and 

 g}'psum. They outcrop over hundreds of thousands of square miles in 

 the territory embraced by Wyoming, Colorado, New Mexico, Kansas, 

 Oklahoma, and Texas. They are late Pennsylvanian in age. Mr. 

 Knight attempted to prove that the "red beds" are for the most part 

 continental in origin, and that the climate was arid to semi-arid. By 

 means of type geological sections A and B some fifty miles apart, by 

 three block diagrams illustrating the relief at various stages in the his- 

 tory of the region, and by ten lantern slides the speaker proved his con- 

 tentions. In summing up, Mr. Knight stated that heretofore the "red 

 beds'' had been regarded as of marine origin, rather than of continental. 

 His presentation of the subject argues for the torrential, fluvial, and 

 seolian origin of the greater part of the deposite instead of the marine 

 one. The Upper Pennsylvanian age of the lower 800 feet of the "red 

 beds" was determined from a pelecypod fauna found in the thin lime- 

 stone member of Section A, The paper was discussed by Doctors Gra- 

 bau, Finlay, Johnson and Eeeds. 



Dr. Berkey stated that the rock formations penetrated by the various 

 tunnels of the Aqueduct were at many places not at all stable. The 

 causes of instability are chiefly of two kinds. First: The excessive 

 rock decay, represented both by badly fractured crush zones through 

 which water has circulated to considerable depth, and also a few places 

 where superficial decay matters of pre-glacial origin are still preserved 

 beneath the drift. Very many crush zones with weakened material were 

 encountered. The most extensive development of weathered rock of 

 superficial relations was in the vicinity of Garrison in the Highlands, 

 v/here the tunnel extended for several hundred feet through such ma- 

 terial. Second: A type of instability of very different character is rep- 

 resented by rock which is under strain and which tends to relieve itself 

 when the support is removed, as happens in the case of tunneling or shaft 

 construction, allowing slabs to break off from the walls sometimes with 

 considerable suddenness and noise. This is called "popping-rock" by 

 the workmen and has been a source of considerable danger. It has been 

 observed in several different formations, most prominently in the Esopus 

 shales, the Storm King granite, and the Eavenswood granodiorite. The 

 author imdertook to explain in some detail the condition exhibited at one 

 of these places in the vicinity of Cornwall on the Hudson, where it was 



