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The Abdominal Method of Sinpring and 

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 By Clifton E. Wins, M.D. Boston. Pp.8. 



Abridgment of the Nautical Almanac for 1881. 

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The Geological and Natural History Survey 

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Drainage for Health, or Easy Lessons in San- 

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Report of the United States Fish Commis- 

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Introduction to the Study of Indian Lan- 

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 to be collected. By J. W. P.)well. Washing- 

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 1880. Pp. 328. 



James Smithson and his Bequest. By Wil- 

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Sketches and Reminiscences of the Radical 

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The Logic of Christian Evidences. By G. 

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Extracts from Chordal's Letter. American 

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 1880. Pp.320. $1.50. 



Elementary Projection Drawing. By S. Ed- 

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A Text-Book of Elementary Mechanics. By 

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POPULAR MISCELLANY. 



The Age of tbe Trenton Gravels, The 



age of the gravel in which flint implements 

 have been found at Trenton, New Jersey, is 

 carefully discussed by Mr. Henry- Carvill 

 Lewis, in a paper read by him before the 

 Academy of Natural Sciences of Philadel- 

 phia. Mr. Lewis divides the surface for- 

 mations of southeastern Pennsylvania into 

 five clays and four gravels, of which nine 

 deposits the Trenton gravel, as he calls the 

 implement-bearing formation, is, except the 

 recent alluvium, the most recent. At Phil- 

 adelphia it is called the river-gravel and 

 sand, and contains pebbles which are made 

 exclusively from the rocks forming the up- 

 per valley of the Delaware River, and which 

 have the flat shape characteristic of all true 

 river-gravels. It is confined to the imme- 

 diate vicinity of the river, and has been 



traced as far up as the Water-Gap. Through- 

 out its whole course it lies within a channel 

 previously excavated through the bowlder- 

 bearing Philadelphia brick-clay and its red 

 gravel, which have been shown to belong to 

 the Champlain epoch. It is therefore later 

 than those formations. The deposit is spread 

 out to its greatest extent at Trenton, where 

 the long, narrow valley of the Delaware, 

 with its precipitous banks and continuous 

 downward slope, opens out into the wide, 

 alluvial plain at a lower level. The fluvia- 

 tile character of this gravel is shown by 

 evidence of various characters, as by the 

 exposures of the " flow-and-plunge struc- 

 ture," in which the layers are seen to dip 

 up-stream, as would be expected to result 

 from the action of downward-flowing wa- 

 ter, while the tertiary gravels show in their 

 layers, dipping southeast, evidence of their 

 deposition by incoming oceanic tides. It 

 frequently, also, instead of lying in a flat 

 plain, forms banks with a higher ground 

 close to the present river-chainnel, and slop- 

 ing down toward the ancient bank, as often 

 takes place according to the laws of river 

 deposits. The formation can not, however, 

 have been made under the operation of any 

 such flood as has been known within the 

 historical epoch, for no such flood has sup- 

 plied the amount of water which would be 

 required. It also bears marks of ice-action. 

 It may then be ascribed to a glacier ; not to 

 the great glacier of the glacial period, for 

 that glacier at its melting deposited the 

 much older brick-clay and red gravel, but 

 to another more recent glacier whose flood 

 flowed through a channel excavated in the 

 deposits of the first glacial period. This 

 second glacier was much smaller than the 

 first, had its southern extremity confined to 

 the valley, and probably corresponded with 

 the age which European geologists style 

 the Reindeer period. From the fact that 

 the palaeoliths found here are similar to the 

 stone implements found among the Esqui- 

 maux, Mr. Lewis thinks that they may be 

 the relics of an Esquimau race who once 

 lived in the valley, and he suggests the Es- 

 quimau period as a suitable name for their 

 age. Finally, he sums up his conclusions as 

 follows: "1. That the Trenton gravel, the 

 only gravel in which implements occur, is a 

 true river deposit of post-glacial ago, and 



