. Annals of the New York Academy of Sciences. Science. r MOOK, STUDY OF THE MORRISON FORMATION 167 Grabau makes the following statement regarding flood-plain sediments: "From the nature of the deposits on river flood plains, perfect and often very fine stratification is to be expected. This may be considered as char- acteristic of typical flood ; The Po, Ganges and Hoangho are given as examples. Davis (1900, 9) states that the proportions of fine to coarse materials in these rivers is very great. In general, levelness of surface is a characteristic of flood-plains; the materia
. Annals of the New York Academy of Sciences. Science. r MOOK, STUDY OF THE MORRISON FORMATION 167 Grabau makes the following statement regarding flood-plain sediments: "From the nature of the deposits on river flood plains, perfect and often very fine stratification is to be expected. This may be considered as char- acteristic of typical flood ; The Po, Ganges and Hoangho are given as examples. Davis (1900, 9) states that the proportions of fine to coarse materials in these rivers is very great. In general, levelness of surface is a characteristic of flood-plains; the material may vary from coarse to fine, the former usually occurring in greater abundance near the source and the latter at a distance from the. Fig. 94.—A trihutary of the Grand River, near Mack, Colorado. Streams of this character were probably abundant in the Morrison area during the deposition of the formation. source; and overlap away from the source of supply is characteristic. The strata deposited will often approach horizontality over considerable areas. Thinning out and replacement of beds is com~mon. Footprints and similar structures are often found. Color of Sediments In moist or pluvial climates with moderate vegetation, the soil is apt to be bluish. Vegetation prevents a high degree of oxidation. "In seasons of dryness, when the amount of vegetation is small, the iron of the sediments of deltas and alluvial fans may become thoroiighly Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original New York Academy of Sciences. New York, New York Academy of Sciences
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