folding, faulting, and brecciation
Plate xxiv, Jaspilite from Grand Rapids Mine, Negaunee
illustrating Charles Richard Van Hise (1857-1918 *) and William Shirley Bayley (1861-1943). The Marquette iron-bearing district of Michigan, with atlas. Including a chapter on the Republic Trough, by Henry Lloyd Smith. Department of the Interior. Monographs of the U.S. Geological Survey. XXVIII. 1897.
"The jaspilites are rocks consisting of alternate bands, composed mainly of finely crystalline, iron-stained quartz and iron oxide.... The folding, faulting, and brecciation of the jaspilites are precisely like those of the ferruginous chert, except that in the jaspilite they are more severe. The interstices produced by the dynamic action are largely cemented with crystalline hematite, but magnetite is present in subordinate quantity."
(Have so far found no mention of the two emphatic intrusions.)
tags: C. R. Van Hise; W. S. Bayley; brecciation; iron; iron-bearing districts; jaspalite