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BULLETIN OF THE 



do,- on account of their origin. Whether this is the spot or not, it is 

 evident from the language of Mr. Agassiz's paper that the gentlemen 

 took their facts and drew their concUisions while they were within the 

 trappean belt, not having found the junction at all, it being some dis- 

 tance below the falls, not at them. From Prof. Pumpelly's state- 

 ment it would seem that he had made the same mistake, as likewise 



J 



Mr. Foster had done years before.* Something more is necessary to 

 be observed than simply to find a sandstone or conglomerate on the 

 eastern side ; it is necessary to pi'ove that it is part of the eastern sand- 

 stone, and not a bed intercalated' in the trap. The sandstone and mela- 

 phyr, a short distance below the dip last given, has a dip of 20°, still 

 inclining to the northwest. The last melaphyr sheet underlies a sand- 

 stone dipping at this angle, and is itself underlaid by another sandstone 

 having the same dip. In other words, the last trap on the eastern side 

 of Keweenaw Point is a thin flow of only some two feet in thickness, at 

 this locality, and is intcrbedded between sandstones which innncdiately 

 above and below^ it have the same dip that it has. As the river is fol- 

 lowed- downwards the dip gradually declines in steepness, although still 

 dipping northwest. The last dip measured was N, 45° W. 5^ The 

 conglomerate and sandstone below the first basaltic flow, i. e. that near- 

 est to Torch Lake, has apparently been acted upon by hot waters. The 

 sandstone has been leached, its fcldspathic constituents largely changed 

 into clay, luul the pebbles are greatly altered and kaolinized. The con- 

 stitution of the sandstone and conglomerate appears to have been origi- 

 nally the same as that of the bands intcrlaminatcd with the trap, except 

 80 far as they fire modified by the detritus of the latter. In many places 

 tliis hot-water action has bleached the sandstone and leached out of it 

 all the argillaceous material, leaving it a nearly pure siliceous sandstone 

 (518). This h:is also converted some of the finer beds into a fine-grained, 

 hio-hly ar^/dlaccous sandstone or arenaceous clay, these beds having prob- 

 ablv arrested the progress of much of the argillaceous material (519, 

 520). This water action would certainly account for the absence of fos- 

 siliferous I'emains in the'sandstone exposed to its effects. Considerable 

 mica in fine scales was seen in the argillaceous bands. Specimeus of 

 the various pebbles were taken from the conglomerate (513, 514, 515, 

 516, 517). No. 517 is a grayish and rcddishdjrown granitoid-looking 

 rock, and under the lens is apparently composed of feldspar holding 

 quartz grains. Microscopically it is seen to be a crystalline aggi'egatc of 



* Smiatc Docs., 1st Sess. 31st Cong., 1849-50, 111. 782 ; Executive Docs., Ut 

 Sess. 31st Cong., 1849-50, IX. Doc. G9, p. G7. 



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