1884-1 177 [Wadsworth. 



in geological age in sandstone formed fifteen minutes before the 

 beginning of these eruptions. However, it was pointed out by me 

 in 1880 that the eastern sandstone (now admitted to be such) did 

 contain this debris on the Hungarian River 1 and elsewhere. 



It was also pointed out that the colorless condition and the ab- 

 sence of argillaceous material in the eastern sandstone at some 

 points was due to bleaching by thermal waters which had likewise 

 bleached and destroyed the felsitic material in portions of the 

 cono'lomerates and sandstones now admitted to belong to the Ke- 

 weenawan series (1. c, pp. 116, 117). 



It was further pointed out at the Sandstone Quarry near Torch 

 Lake, that while the sandstone was composed in part of the same 

 materials as those found in the sandstone in the Marquette district, 

 that it also contained a large proportion of short hexagonal crys- 

 tals of quartz, terminated b}^ pyramids at both ends, the same as 

 the quartz grains are in the old rhyolites (quartz porphyries) in the 

 Keweenawan series. It was further shown that the horizontal so- 

 called bedding planes of this sandstone were joint planes, while 

 the true bedding planes were determined by numerous coarser 

 layers of sand, pebbles, clay masses, etc., which extended long 

 distances approximately parallel to one another at an average 

 dip of N. 45,° W". 15.° It was again stated that this sandstone 

 had been subjected to thermal waters and the felsitic 2 material had 

 been converted into clay or removed. 



While part of the clay masses are distinctly altered pebbles, 

 others which were not taken into account in determining the dip 

 are probably formed from infiltrated clay. Irving throws doubt 

 on the correctness of the above observations by stating he cannot 

 find the same evidence and claims that while he finds traces of the 

 trappean material in the sandstone he finds none of the porphyry 

 material belonging in the conglomerates of the Keweenawan series. 

 This last proves too much, for if as he claims this sandstone must 

 have been deposited against the mixed lava flows and detrital rocks 

 and made up of their ruins, then it should be full of their debris, 

 and the old rhyolitic and trachytic material ought to be far longer 

 retained than the more easily perishable basaltic material. The 

 basaltic debris, indeed, is comparatively rare even in the midst 



1 Ivving admits this in his Final Report, p. 354. 



2 Misprinted feldspathic in Bull. Mus. Comp. Zool., 1880, VII, p. 117. 

 PROCEEDINGS B. S. N. H. VOL. XXIII. 12 NOV., 1SS5. 



