Title: The American journal of science
Identifier: americanjourna4471919newh (find matches)
Year: 1880 (1880s)
Authors:
Subjects: Science
Publisher: New Haven : J. D. & E. S. Dana
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
352 A. W. Giles—Niagara Limestone at Rochester. ence of these cavities has made possible the greater part of the brecciation of the rock. The breccia is of the endolithic type, both crackle and mosaic patterns being represented. All of the fragments are angular and small, the largest having major dimen- sions of a few inches only, while many measure but an inch or even less in their longest directions. The brec- ciation has originated from a number of causes. Some of it is undoubtedly expansion breccia. The Lockport Fig. 2.
Text Appearing After Image:
Fig. 2.—Breccia fragments of Niagara limestone in selenite. Note the rhombs of dolomite in the extreme right at the top and the crystals of sphalerite just to the left of the center. limestone carries a great deal of both gypsum and anhy- drite, especially in the central and upper portions of the formation. In altering to gypsum anhydrite expands greatly, the increase in volume being 60-30 per cent according to Van Hise.3 The force resulting from this expansion repeatedly fractured the containing limestone, the portions of the rock adjacent to the cavities being especially affected, for the stresses found easy relief by forcing the cavity walls inward. 8 A Treatise on Metamorphism, U. S. Geol. Surv. Mon. 47, p. 357, 1904.

Note About Images