JIUSEini OF COMPAKATIVE ZOOLOGY. 



121 



eral places, especially at Copper Falls, west of Houghton, and northwest 

 of Hancock. At the latter locality, marked slates on the map of the 

 Portage Lake district, by A. K. Marvine and L. G. Emerson/^- or, in other 

 words, at the bottom of the ravine below the curve, at the end of the 

 heavy grade of the Mineral Range Railroad, they were examined the 

 most thoroughly, as that locality seemed to be the most probable place 

 to find fossils, if any existed in the sandstone. Although our search 

 ■was unsuccessful, we think it very probable that, if one had the appli- 

 auces for more extended work, fossils might be found here. The con- 

 tact of the sandstone with the traps was not seen here. In the parts 

 nearest the latter it is a coarse, reddish-brown sandstone, composed of 

 reddish feldspar, quartz, and basaltic detritus (387, 388, 409). It is 

 composed of the same materials as the sandstone, interbedded with the 

 basalts, although it perhaps has more basaltic detritus than they do. 

 The enclosed pebbles appear to be trachyte (felsite porphyry), of the 

 same character as those found within the trappcan district near Ilau- 

 cock (3SD). 



As we recede from the traps, the sandstone becomes finer, or passes 

 into a shale composed of the same materials (3D0, 3U1). Lenticular or 

 rounded concretions occur in the shale, which closely resemble pebbles 

 (392). Little spherical concretions of sand, similar to those described by 

 Messrs. Foster and Whitney,! occur here (393, 394). In some of the 

 coarser portions of the sandstone, interstratified with the shale, little 

 fragments and scales of argillite were seen (395). Some of the shale 

 is fine and earthy (398), and in places shows rain-drop impressions (399, 

 400), ripple-marks (400, 401, 402), and mud-flows (403, 404, 405, 408)! 

 About two miles above Hancock the sandstone was formerly quarried, 

 on the shore of the hike. Its dip is N. 30^ W. 23^ The dip of the 

 conglomerates nearer Hancock, interstratified with the traps, is 40°. 

 Any inequality of the lava flows or of the shore deposits of sand and 

 pebbles would give rise to a change in the dip of succeeding beds. 



West of Houghton, sandstone and conglomerate of the same general 

 character was observed dipping N. 45° W. ,30°. It is probable that the 

 Laumontite('*red Zeolitic mineral") which Dr. Rominger describes as 

 occurring here, and also forming the cement of the conglomerates else- 

 where, 1: is the red feldspar of the trachytes (felsitcs). The material of 

 which the western sandstone is composed, and its junction with the 



* Gool. of Mich., I., Atlas, Plate XIV. a. 

 t Kxecntive Docs., 1st Sess. ;Ust Cong., 18t9 

 t Gcol. of Mich., I., Part HI. pp. D7, 93. 



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50, IX., Doc, 69, p. 112. 



