REPORT OF COMMITTEE OX PHOTOGRAPHS. 619 



Contacts, etc. 



31. Unconformable contact of gneiss and Trenton limestone; J mile from Mont- 

 morency falls, Canada. Size, 6x8 inches. Photographed by C. D. Walcott, 

 188'J. 



32.* Base of first Watchung trap-sheet in gorge of Passaic river at Paterson, New 

 Jersey, showing both basaltic columns and bedded trap in the same sheet and 

 contact with Newark shales. Size, 5x7 inches. 



33. Lateral ascent of base of palisade trap across Newark shales at King's point, 



Weehawken, New Jersey. Shore of the Hudson river. Size, 5x7 inches. 



34. Cross-section exposure of base of palisade trap-sheet, showing its contact with 



the Newark shales. West Shore railroad tunnel, Weehawken, New Jersey. 

 Size, 5x7 inches. 



35. Seams in limestone filled with calc-spar. Calciferous formation near Limekiln 



point, Highgate Springs, Vermont. Size, 6x8 inches. Photographed by C. 

 D. Walcott, 1889. 1st view. 



36. The same. 2d view. 



37. Brecciated limestone conglomerate. Calciferous zone, 1 mile south of Highgate 



falls, Vermont. Size, 6x8 inches. Photographed by C. D. Walcott, 1889. 



Jointing. 



38. Obsidian columns. Obsidian cliff, Yellowstone National Park. Size, 6x8 inches. 



Photographed by J. P. Iddings and described in the 7th Ann. Rep. of the U. 

 S. Geol. Survey, 1888, pp. 249-295. 



39. The same, near view, showing horizontal lamination of obsidian columns. 



40. The same, showing lithoidal portion. 



41. Columnar basalt, O'Rourke's quarry. Orange mountain. New Jersey. Converging 



columns in middle of quarry. Size, 6x8 inches. Photographed by J. P. 

 Iddings and described in Am. Jour. .Sci., 3d ser., vol. XXXI, 1886, Dp. 

 321-831. 



42. The same, northern end of quarry. 



43. The same. Southern end, showing the curved, tapering ends of vertical columns 



and the junction of two groups of small columns. 



44. The same, showing converging columns and large vertical columns. 



45. The same, showing large vertical columns with spheroidal parting and transverse, 



chiseled structure. 



46. The same. 



47. Table mountain, Golden, Colorado. Shows effect of unequal, horizontal, tabular 



jointing in dense part of a thick basalt sheet. Size, 8 x 10 inches. Photo- 

 graphed by Whitman Cross, 1886. 



48. Cliffs in Topman's gulf, Jefferson county. New York. Lorraine rocks ; Utica 



shale with interbedded sandstone of the Lorraine series coming in above. Size, 

 6x8 inches. Photographed by C. D. Walcott, 1889. 



49. Joints in granite, Mount Lyell, California. Size, 8 x 10 inches. Photographed 



by I. C. Russell, September, 1883. 



CLEAVAGE and WEATHERING. 



50. Middlequarry of thePenrhyn slate company, Middle Granville, Washington county, 



New York. Illustration of the bedding of the roofing slate. It is coincident 

 with the line of cleavage. Size, 6x8 inches. Photographed b}^ C. D. Walcott, 

 September, 1890. 



*32, 33 and 31 photographed by N. H. Darton, 1887, Bull. 67, U. S. Geot. Survey, 1890. 



