erratics / 3
*
Fig. 6.—Very strongly glaciated Permo-Carboniferous pavement of siliceous quartzite, 9 feet by 3 feet, on the southern slope of Strangway’s Hill, Inman Valley. The striated floor, which is of unknown extent, is covered with bowlder clay, and the photographed portion was freshly uncovered by the writer. W. Howchin, photo.
(cropped to square; decolorized; levels 0 .90 255)
ex Walter Howchin (1845-1937 * †). “Australian Glaciations.” The Journal of Geology 20 (April-May 1912): 193-227
Smithsonian copy, scandate 20100526
Harvard copy, digitized July 26, 2007 (opens to above image)
from which volume (all located in Howchin's paper), these adjacencies —
Erratics
agency, argument in favor of, 210
among, 201
angular masses of slate among, 210
composed, 198
contained, 198
elongated, 197
dispersal of, 201
throughout its entire extent, 198
placed the question beyond doubt, 196
nature of, 195
those which possess, 196
mostly of a moderate size, 210
large, 205
numerous large, 200
of all sizes, 200
foreign to the locality, 200
some of, 222
thickly strewn, 200
numerous, 208
plentiful... and, in many instances... irregularly worn, 208
(found with) grooved and striated rock surfaces, and perched blocks, 218
many, included, 206
mostly rounded, 214
scattered, perched, and lineal, 221
nearest source for such, 210
met with at various horizons, 211
frequently indent the floor on which they are dropped, 212
—
Howchin’s photo is not of an erratic, but of glacially striated pavement, witness and bearer of the land ice that transported and abandoned them. Such out-of-context rocks are something like the precipitant words and images in many of these posts, what’s left when all else has burned off.
This volume of The Journal of Geology is a rich source for my sideways purposes: this Howchin paper, L. V. King’s references to Love, and Pearl Gertrude Sheldon, her “Some Observations and Experiments on Joint Planes,” Parts I 53-79 and II 164-183.
tags:
adjacencies; erratics; index; striations
H. Howchin; Pearl G. Sheldon; L. V. King; A. E. H. Love