52 THE GEOLOGY OF MINNESOTA. 



[The Puckwunge conglomerate . 



stratification, is cut by a dike nine feet wide and is covered with a surface diabase 

 flow or a succession of flows. .It here embraces distinctly quartz-porphyry and debris 

 from the hardened elastics of the Animikie. The Animikie was therefore upturned 

 by eruptive disturbance and the whole series of red rocks which appear as a result 

 of fusion of the Animikie on the east flanks of mount Josephine and at the head of 

 Wauswaugoning bay, and on Pigeon point, had been produced prior to the date of 

 this conglomerate.* 



From the region of Grand Portage this conglomerate extends eastward under 

 the surface of lake Superior, reappearing at the southwestern end of Isle Royale, 

 where it is coarse and quartzose, and where it is in like manner overlain first by 

 some trap sheets (No. 562) and then by a hard sandstone. 



Towai'd the southwest it is believed to be at first less developed. Its upper 

 parts are apparently replaced by sandstones having a red color or by red laumontitic 

 conglomerates. As such it appears a short distance up the Baptism river, while 

 along the shore further east as far as to Little Marais and Manitou river are several 

 conglomeratic bluffs at the lake shore, which are probably representatives of the 

 same general horizon, separated by lava sheets and modified by an abundant supply 

 of igneous basic debris. 



The next that is known of it is in the valley of the St. Louis river, where it 

 affords conspicuous exposures, as described and illustrated in the chapter devoted to 

 Carlton county, and, according to the record of the deep well at Short Line park 

 (Duluth plate), is separated from the Thomson slates by a series of igneous rocks 

 having a thickness of ninety-one feet, although along the river it lies on those slates. 



At New Ulm, but on the north side of the Minnesota river, is an unequivocal 

 outcrop of the same conglomerate. It here lies on red granite, probably of the age 

 of the red granite, or red rock, of the gabbro age, and its pebbles are coarse and varied, 

 some of them being of the peculiar jasper called taconyte (Nos. 852B, 852C), a striking 

 and unmistakable index of parallelism with the Puckwunge conglomerate of the 

 northeastern part of the state. f It here lies below a large quartzyte formation 

 which is well known, both in Minnesota and Wisconsin, in the latter state having 

 been called Baraboo quartzyte, while it received from Dr. C. A. White, of the early 

 Iowa survey, the name Sioux quartzyte. 



In addition to these localities, Sweet has described it in T. 32-6 W., Wisconsin, 



*The reader is referred for a consecutive discussion of this interesting distinction to the following literature: 



Tenth Annual Sepnrl, Minnesota Survey (for 1879) [1882] pp. 45, 46. Description of the rock section 



Copper-Bearing Rocks of lake Superior. Mon. r, I'. S'. Geological Survey, 1883, pp. 297, 367, 405, and figure 16 on p. L X .I7. 

 The conglomerate is referred to the Auimikie by Irving. 



Note on the Keweenawan Rocks of Grand Portage island, north coast of lake Superior. American CJmlnijixl, xiii, p. 437. 

 Grant here shows that the conglomerate belongs in the Keweenawan, probably near the bottom. 



The anorthosytes of the Minnesota shore of lake Superior, Bulletin viii, Minnesota Survey ; and The Norian of the North- 

 west, an introduction to the last. Here is emphasized the necessity of separating the gabbro from the rest of the Kewuenuwan. 

 thus dividing the Keweenawan, as denned by Irving, into two parts. 



The eruptive and sedimentary rocks of Pigeon Point, Minnesota. Bulli-tin i-ij . I '. S. Oeol. Survey, 1893. Bay ley here shows 

 that the quartz-porphyry and red rock are formed by fusion of the Animikie by the gabbro. 



t A rational view of the Keweenawan. N. H. WINOHELL. American Geologist, vol. xvi, p. 150. 



