Pre-Cambrian Geology of North AmericaU.S. Government Printing Office, 1909 - 939 sider |
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Algonkian amygdaloids Animikie anorthosite Archean argillite Azoic bands basal basic beds belt Cambrian chloritic clastic conglomerate consists Copper-bearing correlation County Coutchiching crystalline limestone crystalline rocks deposits describes diabase dikes diorite dolomite east eastern eruptive feet felsite folded fragments gabbro Geol geology gneiss gneissic granite granites and gneisses graywacke green schists greenstone Hise horizontal hornblende hornblende schists Huronian Huronian rocks Huronian series igneous rocks interstratified intrusive iron formation iron-bearing jasper Keewatin Keweenaw Point Keweenawan Lake Superior Lake Superior region later Laurentian limestone lithological Lower Huronian Marquette district masses Menominee Mesabi metamorphic metamorphosed mica schists mica slate micaceous miles Minnesota Mountain Nipigon occur origin overlying Paleozoic pebbles Penokee places porphyry Potsdam pre-Cambrian quartz quartzite range Rept River sandstone schistose schists sedimentary rocks sediments shales siliceous Silurian strata structure syenite Taconic thickness tion trap unconformably Upper Huronian Vermilion volcanic WINCHELL Wisconsin
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Side 493 - In the third and uppermost horizon, consisting of beds of graphite, occurred great numbers of spicules of apparently hexactinellid sponges. "Between this upper Laurentian system and the basal Cambrian occurs," says Matthew, " a third system, the Coldbrook and Coastal, Huronian, which has given conglomerates to the Cambrian and has a great thickness.
Side 117 - Superior, we have the following conclusions : " On the whole, we are disposed to regard the specular and magnetic oxides of iron as a purely igneous product, in some instances poured out, but in others sublimed from the interior of the earth. The supposition entertained by some that...
Side 448 - ... follow the outcrop of each important mass in all its windings as far as it can be traced, until it becomes covered by superior strata, is cut off by dislocation, or disappears by thinning out.
Side 713 - ... slate — in fact, all possible gradations and mixtures of the minerals dolomite, hematite, quartz, and such argillaceous minerals as kaolin and chlorite. In the ferruginous rocks associated with the iron ore the iron occurs as hematite and also in the form of carbonate, isomorphous with...
Side 386 - Part II. Keweenaw Point with particular reference to the felsites and their associated rocks by LL Hubbard.
Side 545 - Report on an Exploration in 1875, between James Bay and Lakes Superior and Huron.
Side 33 - The fauna includes four species of annelid trails and a variety that appears to have been made by a minute mollusk or crustacean. There also occur in the same shales thousands of fragments of one or more genera of crustaceans.
Side 115 - Near lYAnse is a limited patch of limestone which has a dip to the east of 25° to 30°, the limestone being distinctly stratified. The sandstone about a quarter of a mile to the north is horizontal, and it seems evident that the limestone overlies the sandstone, although the position of the inclined beds of the more southerly portion of the limestone is difficult to explain, since the surrounding country is low and level and underlain by sandstone and horizontal beds.
Side 736 - Granite is the principal mountain-making rock in the Wichita region. Its area is greater than that of all the other igneous rocks combined, and is about equal to that of the others and the older Paleozoic sediments. It makes all of the high land of the Wichita, Quana, Devils Canyon, and Headquarters mountains, and a large part of the Raggedy group. "The relations of the granite to the gabbro indicate that the granite is younger and that it intrudes the gabbro. Both occur in large masses, as shown,...
Side 254 - ... dip, at a high angle usually. But- subsequently a very extensive outburst of granite, with some syenite, has taken place, to the great disturbance of the stratified rocks, and penetrating them both in intercalations and crosswise. These intrusive rocks occupy a very large portion of the lake, most of the western shore, nearly all of the eastern trough or arm.