Geological Survey of Michigan, Volume 4authority of the Legislature of Michigan under the direction of the Board of Geological Survey, 1881 - 248 pagina's |
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Veelvoorkomende woorden en zinsdelen
actinolite aphanitic arenaceous argillitic banded beds bluffs brecciated Carp River chloritic color compact composed corner of Sect creek crystalline crystals dark deposits dioritic rocks dioritic schists doleritic drift drift-covered dyke east exposed exposures farther feet feldspar feldspathic ferruginous fine-grained formed granite granular granules ground-mass half of Sect hematitic high angle hills hornblende Huronian hydro-micaceous inclosing interlaminated intermixture intersected interstratified iron oxide iron-ore jasper-banded knobs Lake laminated large belt large succession layers ledges limestone line of Sect locality lower lustre magnetite Marquette martite mass massive Menominee Menominee River mica micaceous Michigamee mile mines N.W. quarter Negaunee north side novaculitic occur ore-bearing ore-belt ore-formation outcrops partly quarter of Sect quarter-post quartz quartzite formation quartzose Quinnesec ridge rock-beds rock-belt rock-mass rock-series S. E. quarter sand-rock schistose schists seams sedimentary sericite serpentine siliceous Silurian slates slaty slope south side specular strata structure Sturgeon River surface test-pits thickness Town valley vertical
Populaire passages
Pagina 97 - ... from the size of a pin's head to that of a pea ; scattered through a large body of sand or clay ; and in this state it is called by the Mandingoes sanoo munko,
Pagina 6 - Huronian sediments began to form, while according to my own observations the granites of Marquette are eruptive masses which came to the surface after the Huronian beds were already formed, and by their eruption caused not only the great dislocations of the Huronian formation, but the half-molten plastic granite masses induced by their contact with the Huronian rock-beds, also their alteration into a more or less perfect crystalline condition, and commingled with them so as to make it an embarrassing...
Pagina 82 - By boring with the diamond drill it has been ascertained that the whole swamp valley on which Ishpeming is located is underlaid by the iron formation. The ore-bearing beds in the Lake Superior mine lie in steep inclination, with northern dip directly on the diorite, or on schistose beds belonging to this group, but in other parts of the mine the strata are seen to be bent and folded repetitiously, and to dip in the most irregular way — much more so than in the Cleveland and New York mines.
Pagina 210 - The whole succession is so near to a vertical position that in many instances it has to be left uncertain which way they dip, but suppose their dip is conformably to the south ; the upheaval of the diorites by the eruption of the still more southern granite masses pushing the whole...
Pagina 6 - ... limestone comprises an important share of this group. The seven previous groups, considered to be a succession of sedimentary strata, are intersected by various dikes, among which are a dioritic rock and dolerite dikes, the latter of which are later in age than the former. No proof has been found of any discordance between the granites of Marquette and the adjoining Huronian beds. On the contrary, outcrops of the two kinds of rocks exhibit a...
Pagina 6 - ... before the Huronian sediments began to form, while according to my own observations the granites of Marquette are eruptive masses which came to the surface after the Huronian beds were already formed...
Pagina 209 - Haubury slate gronp and upward we rarely find a bed so much altered that its sedimentary structure is altogether obsolesced, and the majority of the strata shows it very plain, while in the dioritic rocks, considered to...
Pagina ii - BLISS for the State of Michigan, in the Office of the Librarian of Congress, Washington...
Pagina 209 - ... evidently been transformed under cooperation of heat and partially brought into a plastic condition, which is shown by the extreme corrugation and mode of intermixture of those rock masses, of which effects the other rock groups do not exhibit near as high a degree. It would be very strange, then, if the lowest beds nearest to the focus of the central heat should have been so much less affected by these altering influences than those pretended to be the higher upper strata of the rock crust....
Pagina 7 - Marquette region, are unnecessarily multiplied into vaguely defined subdivisions. Subsequently Major Brooks identified strata of the Menomenee River district as representatives of Groups 15 to 20, which lithologically have no similarity with those of the Marquette district, adding still more to the confusion already existing. Describing the Huronian series, I propose to make the following subdivisions in an ascending order : I. Granitic group. II. Dioritic group. III. Quartzite group. IV. Iron group....