116 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 conclusions 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 

 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 prove that it is part of the eastern sand- 

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

 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 interbedded between sandstones which immediately 

 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 feldspathic constituents largely changed 

 into clay, and 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 interlaminated with the trap, except 

 so far as they are modified by the detritus of the latter. In many places 

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

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

 (518). Tiiis has also converted some of the finer beds into a fine-grained, 

 highly argillaceous sandstone or arenaceous clay, these beds having prob- 

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

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

 siliferous remains in the sandstone exposed to its effects. Considerable 

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

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

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

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

 quartz grains. Mici'oscopically it is seen to be a crystalline aggregate of 



* Senate Docs., 1st Sess. 31st Cong., 1849-50, III. 782; Executive Docs., 1st 

 Sess. 31st Cong., 1849-50, IX. Doc. 69, p. 67. 



