This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 Excerpt: ...sand as a matrix. When in quantity the sand may be more or less cross-bedded; the grains vary from angular to rounded. The component pebbles of the rock are usually of material of local origin; they are uniform in size and are ordinarily well rounded. The stratification of marine conglomerates is usually well marked ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 Excerpt: ...sand as a matrix. When in quantity the sand may be more or less cross-bedded; the grains vary from angular to rounded. The component pebbles of the rock are usually of material of local origin; they are uniform in size and are ordinarily well rounded. The stratification of marine conglomerates is usually well marked and crossbedding may be more or less perfectly developed. In the normal cycle of sedimentation, following an encroaching sea, finer material will overlie the coarse and may locally interdigitate with it. Local unconformities and irregularities may be expected along the dip but great persistence and uniformity is common along the strike. In general, true marine conglomerates are not thick; Barrell11 states that their thickness is usually less than one hundred feet. Mansfield has cited the Cretaceous of Texas as a typical example of a series of marine deposits. The Trinity sands, described by Hill,12 as the basal formation, have as their lowest member a fine pebble conglomerate, consisting of small masses of the adjacent pre-existing rocks in a cement of ferruginous yellow and red gritty sand. Most of the coarser material is well rounded and sorted, though in some localities it is predominantly subangular with only the more resistant quartz, which has travelled a long distance, well rounded. The basal conglomerate grades upwards into sands, grits, and silts; it is seldom over two hundred feet thick. Both massive and well-bedded deposits occur in the formation; sands and clays are interstratified with the conglomerate in places, while elsewhere the beds are dominantly coarse. Other typical marine conglomerates, deposited in an encroaching sea, are abundant in the stratigraphy of the western part of the United States. Among them might be mentioned t...
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Add this copy of Age of Strata Referred to the Ellensburgh Formation in to cart. $56.24, good condition, Sold by Bonita rated 4.0 out of 5 stars, ships from Newport Coast, CA, UNITED STATES, published 2011 by Nabu Press.