TITLES AND ABSTRACTS OF PAPERS 87 



ILLUSTRATIONS OF INTRAFORMATIONAL CORRUGATION 

 BY JOHN M. CLARKE 



(Al)stract) 



An effective view of an exposure in the Grande Gr^ve limestones, referred 

 to by Logan and very difficult of access; also some suggestions in regard to 

 the corrugated Hillsborough (New Brunswick) gypsums, supplemented by an 

 illustration deposited nearly a century ago in the Albany Institute. 



Presented in full without notes. 



Discussion 



Mr. F. Berckhemer gave examples of probable "subsolifluction" from the 

 Upper Devonic at Mill Rifts, Delaware River, Pennsylvania ; the Beekmantown 

 of East Creek, New York; the Quaternary clays at Catskill, New York, and 

 the Upper Malm of Mergelstetten, Wurttemberg. 



Dr. Henry M. Ami : In the Province of Quebec, Canada, similar corrugations 

 occur in the brow^n-colored shales of Upper Ordovician (Lorraine) age, on the 

 north side of the Island of Orleans. The corrugated layer, in some instances, 

 is only 5 inches in thickness, over which and under which are perfectly hori- 

 zontal and undisturbed strata. At Hillsborough, in New Brunswick, the 

 gypsiferous deposits present evenly banded structure, between which there 

 occur neatly folded layers in the form of ribbon-like corrugations. These 

 folds, when seen on the divisional planes of stratification, have the appearance 

 of ripple-marks, but are probably quite distinct. 



Dr. D. W. Johnson mentioned a case of intraformational folding and fault- 

 ing in the Triassic beds of southern Utah, under conditions which suggested 

 slumping on delta front. 



Prof. R. D. Salisbury called attention to crumpled postglacial laminated 

 clays where slumping is not applicable, since the layers now crumpled as to 

 their laminae are themselves horizontal. 



Prof. N. M. Fenneman : A thick bed of cherty limestone in the Saint Louis 

 formation is brecciated, though included between undeformed beds. Here the 

 chert is so broken as to show sharp comers almost splinters, as though the 

 chert was formed before the deformation of the bed. 



Prof. N. H. WiNCHELL referred to postglacial crumpled lacustrine beds seen 

 by him in the Mississippi Valley and of similar crumpling in the northern 

 Minnesota in the Archean. The former, he said, he had attributed to the 

 actions of a second ice-sheet crowding and folding previously deposited sedi- 

 ments. Since the announcement by Coleman of the glacial origin of the 

 Archean (Ogishke) conglomerate he had latterly been inclined to assign the 

 latter mentioned crumplings to the same cause, thus showing a possible identi- 

 cal force operating at the extreme ends of the geological scale. He stated 

 that photographic illustrations of the Archean crumpled beds are to be seen 

 in volume IV of his report on the geology of Minnesota. 



