560 THE MARQUETTE IROKBEAEING DISTRICT. 



of limestone-building was too near shore and the water too shallow for a 

 pnrenon fragmental formation to be built up, especially as vigorous erosion 

 still continued on the adjacent land, and hence it is that even the purest 

 dolomite beds bear a greater or less quantity of fragmental material, while 

 they are frequently interstratified with shale, graywacke, and quartzite. 

 Because the sea had not yet overridden the lands of the central part of the 

 district, the Kona dolomite is limited to its eastern part. On the south 

 side of the district the westernmost exposures occur at Goose Lake, and on 

 the north side the most westerly exposures which clearly belong to this 

 formation are those at Morgan Furnace, although a belt of slates very 

 similar to those associated with the Kona dolomite occurs interstratified 

 with the quartzites east of Teal Lake. This belt feathers out about 1 mile 

 east of Teal Lake, and this suggests that here was the western limit of the 

 shore-line at the end of Kona time. 



As a consequence of the upbuilding of the Kona formation, combined, 

 perhaps, with a cessation of subsidence, the waters again became shallow, 

 and there followed above the Kona dolomite the Wewe slate. The inter- 

 mediate conditions favorable for mud deposits continued for some time. On 

 the south side of the district the western limit of the shore-line at this time 

 was in the eastern half of sec. 21, T. 47 N., R. 26 W., and on the north side 

 probably at or near Teal Lake. By the upbuilding of the beds the waters 

 became shallower and shallower until the waves of the sea were able to 

 transport sand throughout the area submerged. There is evidence that in 

 some localities the compacted mud arose near to or above the surface of the 

 water, so as to be cut by the waves and yield fragments to the succeeding 

 sandstone. The sandstone has been subsequently indurated to a quartzite, 

 and hence there follows above the Wewe slate the Ajibik quartzite. 



During the time of the deposition of the Kona dolomite and Wewe slate 

 the sea did not advance very rapidly, but erosion had been steadily wearing 

 down the highlands, and during the deposition of the sandstone following 

 these formations there was a rapid advance of the sea toward the west. 

 On the north the sea of Ajibik time pushed west to Michigaiume, and 

 on the south as far west at least as the Goodrich mine. The sea there- 

 fore gained farther at the north than at the south, the shore-line apparently 



