TITLES AND ABSTRACTS OF PAPERS 157 



vania, which are thought to have been intruded prior to duplication, are shown 

 to furnish a most striking proof of the truth of the above theory. 



REMARKABLE PERSISTENCE OF THIN HORIZONS 

 BY GEORGE HALCOTT CHADWICK 



{Abstract) 



A very unusual case of the persistence laterally for scores of miles of numer- 

 ous intercalated thin beds of black shale and of limestone, often but half an 

 inch and seldom over a foot thick, is afforded by the upper Devonian Hanover 

 shale of Cattaraugus and Erie counties, New York. Several of these beds have 

 been traced from Lake Erie to the Genesee River. Zones of small concretions 

 in the green shale are equally persistent. 



PORTAGE STRATIGRAPHY IN WESTERN NEW YORK 

 BY GEORGE HALCOTT CHADWICK 



(Ahstract) 



Published correlations of the Lake Erie Upper Devonian with the Genesee 

 standard column have been admittedly pro^^isional, due to the difficulty of 

 tracing formational units across a gap in the topographic mapping. During 

 the past summer the writer had an unusual opportunity to complete this de- 

 tailed tracing, with results notably different from those expected. The field 

 relations of the published sections are found to be as follows : 



Genesee River Section Lake Erie Section 



(Portland beds 

 (Present, included in Chemung beds ) . . j j^^^^.^j^ ^^^^^ ^^^^^ 



Long Beards Riffs sandstones ( disconf ormity ) 



Wiscoy shales Hanover shales 



Nunda sandstones (disconf ormity) 



Gardeau beds Angola shales 



Grimes sandstone ( disconf ormity ) 



Hatch shales Included in Rhinestreet 



Rhinestreet black shale. 

 Cashaqua green shale continuous to 

 Lake Erie. 



For the name Portland, preoccupied and withdrawn, it is proposed to sub- 

 stitute Gowanda. These beds are terminated above unconformably by the 

 Laona sandstone, which with two or three hundred feet of overlying strata 

 appears to be cut out eastward by this unconformity, bringing beds apparently 

 equivalent to the Girard shale of Pennsylvania down on the attenuated Go- 

 wanda near the Genesee River. It is thought this large overlap may furnish 

 a more satisfactory plane of division between Senecan and Chautauquan. 



8TR0MAT0P0RA GROWTH ON EDGE-ON CONGLOMERATE FROM THE SILURIAN 



BY JOHN M. CLARKE 



At 5.30 p. ni. the Society adjourned. 



