Preliminary report of a geological reconnoissance of Louisiana (Google eBook)

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Office of De Bow's New Orleans review, 1869 - Geology - 15 pages
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Page xvi - River, exists at about the same level that is, near that of tide water not only over all the so-called delta plain of the Mississippi, but also higher up, perhaps as far as Memphis, and all along the Gulf coast, at least from Mobile on the east to the. Sabine River. Wherever circumstances allow, the overlying clay stratum (No. 2) is also observed.
Page xv - ... stump stratum No. 1 was visible to the thickness of 10 feet at its highest point ; showing several generations of stumps above one another, also the remnants of many successive falls of leaves and overflows. The wood is in a good state of preservation ; no prostrate trunks to be seen at present. The main clay deposit, No. 2, varies but little in general character ; although very solid, its tendency to cleave into prismatic forms renders it very liable to "cave
Page xiv - ... Fort Adams, where we find the strata of the (fresh-water) " Grand Gulf group " in a position nearly or quite horizontal ; overlaid, first by the materials of the " Orange Sand," which in its turn is capped by the stratum of the " Loess " or Bluff formation, covered by a thin deposit of " Yellow Loam." Facing southward from the " Blockhouse hill " at Fort Adams, we observe a wilderness of the characteristic sharp ridges of the Loess region, often fore-shortened into veritable peaks, elevated between...
Page xvi - Delta-plain of the Mississippi, but also higher up, perhaps as far as Memphis, and all along the gulf coast, at least from Mobile on the east to the Sabine river. Wherever circumstances allow, the overlying clay stratum No. 2, is also observed. These facts indicate the wide spread prevalence, during the epoch succeeding the drift, of quiet, shallow freshwater lagoons and swamps of slightly varying elevation ; through which the continental waters may for some time have found an outlet without a definite...
Page 47 - that the river is flowing through it (the delta region) in a channel belonging to a geological epoch antecedent to the present.
Page xv - Landing, 1? miles below. Its lower half is washed, and continually encroached upon, by the river ; its upper portion is now inland of an extensive sandbar. The strata are disposed horizontally or basin fashion, and vary a good deal both in thickness and materials, as shown in the subjoined profiles, situated about a mile apart ; the correspondence of strata is ascertained by actual tracing of the stratification lines. At the stage of extreme low water prevailing at the time, the stump-stratum No.
Page xviii - Island, and in its general structure much resembles the latter, to which it is slightly inferior in size, and about equal in elevation ; its highest point, " Prospect Hill," on the north side, being 160 feet above tide-level. An elevated ridge connects Prospect Hill with another high point near the southern slope of the island ; and near the west end a ridge, on which Judge Avery's house stands, falls off steeply toward the Bayou Petite Anse. These three points inclose the valley in which the salt...
Page 49 - Louisiana coast, apart from bejug rather an unpleasant trysting-ground, do not offer to the amateur collector those brilliant inducements which, while in the main conducive chiefly to parlor ornamentation, yet collaterally bring about very frequently the discovery of species heretofore overlooked by professional naturalists. So far from considering the subject in hand exhausted, I intend to pursue it further to the utmost extent of my ability, aided, as I hope, by additional borings into the strata...
Page 54 - But there is yet a wide difference between such effects and the legerdemain machinery of " local upheavals," which is so readily resorted to by amateurs for the explanation of any unusual phenomenon. The geology of the northern Gulf coast has been traced with no pointed graver, but has the rough, broad dashes of a charcoal sketch ; and no mere presumptions based upon partial data can be allowed to upset the general order of things. The difficulty of explaining the presence of a truly " pleiocne stratum...
Page 54 - ... data alone, the question assumes at times somewhat of the aspect of scholastic disquisitions of the olden time. And whether we hold the Darwinian view of the origin of species, or that of Owen, or even the old one of successive independent creations, it is not at all likely that in different localities there should have been simultaneously an equal or similar accretion or extinction of species, at a time when differences of climate were already as strongly defined as now, or even more so.

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