THE LOWER HUEONIAN. 321 



Saganaga Lake and pebbles of greenstone and jasper. The jasper 

 evidently was derived from masses of the Soudan formation which were 

 presumably infolded in the Ely greenstone. This was not present in large 

 quantity and is now buried under the sediments, or, as the result of erosion, 

 it has all been removed and is now found only as pebbles in these sedi- 

 ments; at least no masses in situ have thus far been found. South of the 

 above-mentioned headland, where the conglomerate derived from the Ely 

 greenstone is penetrated by an occasional dike of the Saganaga granite, we 

 find that the pebbles are predominantly greenstone with only an occasional 

 granite pebble. Jasper is also wanting here. As we follow these two 

 belts westward they come closer and closer together, and petrographically 

 they also approach more nearly to each other as the result of the inter- 

 mingling of the granite pebbles and jasper pebbles, until, by the time we 

 reach the first-mentioned area at the west end of the lake, the two conglom- 

 erates are close together and are petrographically the same. Clearly this 

 was the place where the currents mingled the debris derived from the granite 

 on the north side and the greenstone on the south side of this great west- 

 ward-projecting headland, 



The relations of the conglomerate to the underlying rocks are clearly 

 shown by the fact that they consist of pebbles from these underlying 

 rocks, and this relationship can be seen at a number of locations, to which 

 reference has already been made in preceding pages (p. 268 et seq.). The 

 conglomerates have been found in actual contact with the greenstone and 

 with the granite, so that there can be absolutely no doubt as to their 

 actual relationship. Such a conglomerate, lying between the Knife Lake 

 slates and the great greenstone mass forming the Twin Peaks range south 

 of Ogishke Muncie Lake, was described by N. H. Winchell." 



The location of this conglomerate could not be determined from 

 Winchell's statement, but the contact along this range was followed out 

 for a long distance. In many places the slates were found in contact with 

 the greenstone. Where these first contacts were found the greenstone was 

 schistose, and no distinct conglomerate was observed. Eventually, 

 however, on the east slope of the prominent northward-trending hill of 

 this greenstone, at a point 840 paces south and 650 paces east of the 

 meander corner between sees. 27 and 26, T. 65 N., R. 6 W., the greenstone 



«Geol. and Nat. Hist. Survey of Minnesota, Fifteentli Ann. Eept., 1886, pp. 372-374. 

 MON XLV — 03 21 



