Proceedings of the Boston Society of Natural History, Band 23

Boston Society of Natural History., 1888

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Seite 390 - Hydrichthys and the fixed hydroid closely related to it are the resuit of its peculiar mode of life? I believe it is. I believe that the modification in the hydroid Hydrichthys, the loss of tentacles, the polymorphism, and the increase in prominence of the sexual bodies, are exactly what we should expect to find a priori if a degradation had taken place in its structure.
Seite 426 - The gravel in which they [Dr. Abbott's implements] are found is glacial gravel deposited upon the banks of the Delaware when, during the last stages of the Glacial period, the river was swollen with vast floods of water from the melting ice. Man was on this continent at that period when the climate and ice of Greenland extended to the mouth of New York Harbor.
Seite 351 - FREDERICK M°CoY, FGS One vol., Royal 410. Plates, /i. is. A CATALOGUE OF THE COLLECTION OF CAMBRIAN AND SILURIAN FOSSILS contained in the Geological Museum of the University of Cambridge, by JW SALTER, FGS With a Portrait of PROFESSOR SEDGWICK.
Seite 431 - ... oblong. Some of them are from one to three feet in length. These abound for the upper twenty feet of the section on the east side toward the river. One granitic bowlder noticed was about two feet in diameter.
Seite 443 - But in spring, autumn and winter, or, in exceptional years, through much of the summer, it seems probable that the river was confined to a channel, being of insufficient volume to cover its flood-plain. At such a time this plain was the site of human habitations and industry.
Seite 435 - The find reported by Prof. Winchell consists of chipped objects of a class generally ascribed to what is called the rude stone age. Of these many appear to be mere refuse, while others are regarded as finished and unfinished implements. The Winchell specimens have been assigned, upon geological ground, to a prehistoric era antedating that of the mound-building races, and reaching back to a time when the drift material of the terrace-plain was just receiving its final superficial deposit. It is found...
Seite 443 - After the complete disappearance of the ice from the basin of the upper Mississippi, the supply of both water and sediment was so diminished that the river, from that time till now, has been occupied more in erosion than in deposition, and has cut its channel far below the level at which it then flowed, excavating and carrying to the Gulf of Mexico a great part of its glacial flood-plain, the remnants of which are seen as high terraces or plains upon each side of the river.
Seite 444 - When we compare the facts now known from the eastern side of the continent, with those of the western side, they seem to force upon us to accept a far longer occupation by man of the western coast than of the eastern ; for not only on the •western side of the continent have his remains been found in geological beds unquestionably earlier than the gravels of the Mississippi, Ohio and Delaware valleys, but he had at that early time reached a degree of development equal to that of the inhabitants...
Seite 336 - As slab slips on slab, the formerly horizontal beveled surface of every one is canted over, so as to dip in one direction at an angle equal to the change of the inclination of the slabs ; and the surface of every slab is separated from that of its neighbors by faults with upthrow on the side of the direction of dip. The Triassic cover is not strong enough to bridge across from ridge to ridge of the uneven surface thus produced ; its weight is much greater than its strength can bear, and it perforce...
Seite 218 - Head, does not belong to the present or any recent period, but is due to the peroxidation of iron in Triassic and Tertiary times. On the other hand, one of the most striking features of the scenery of the Southern States, especially for Northern eyes, is the bright red color of the soil, and the general predominance of this color over the brownish and yellowish tints. This begins to be noticeable in the latitude of Southern Pennsylvania, and becomes more and more marked as we cross Virginia into...

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