78 LOWER PENINSULA. 



all of which was through bluish shale, with only a few intermediate 

 strata of sandstone. At 1120 feet are bright-red and chocolate- 

 colored shales 40 feet thick, while from there to 1225 feet is white 

 sand rock saturated with brine ; underneath lie shales again. 



Inland from the shore line, whose geological structure has been 

 described in previous pages, we find the greatest part of the 

 surface of Huron County covered by deep drift deposits. The 

 upper coarse-grained sand rock comes to the surface in Bingham 

 township, near the head-waters of Cass River. Similar outcrops are 

 found in the northwestern towns of Sanilac County, in Greenleaf 

 and Argyle, and in Tuskola County, in the towns of Elkland and 

 Novesta, where the bed of Cass River is formed by the upper 

 coarse-grained sand rock inclosing vegetable [remains, Lepidoden- 

 dron. Further up the river, at Indian Rapids, in Town. 13, R. 12, 

 Sect. 7, some lower beds of finer-grained sand rock interlaminated 

 with shale form vertical bluffs about 20 feet high on both sides 

 of the river. One of the interlaminated seams is soft, almost en- 

 tirely composed of mica scales and carbonaceous vegetable sub- 

 stance. The sand rock is mostly thin-bedded, and without fossils 

 as far as observed. 



On the north^side of Saginaw Bay an outcrop of the upper sand- 

 stones of the Waverly group forms the bed of Rifle River for the 

 distance of a mile. The locality is in Town. 21, R. 3, Sect. 16. The 

 rock is coarse-grained, whitish or greenish, with ferruginous spots, 

 moderately soft and irregularly stratified in discordant bedding. 

 Its thickness can not well be estimated, but 30 or 40 feet of the 

 strata are distinctly seen successively rising to the surface. No 

 fossils were observed in it. The hills on both sides of the river are 

 all composed of drift. The strata dip southward, and a few miles 

 lower down calcareous beds of the next higher formation, having 

 the same southern dip, form rapids in the river, but the imme- 

 diate contact between the Waverly rock and these limestones is 

 not seen. 



In this upper portion of the peninsula, no other natural out- 

 crops of the Waverly group are known to me, but the formation 

 has been found in several deep borings made for salt ; two made 

 in Tawas City and one lately at Sable City. Of the latter boring 

 I have no details, being only informed of their success in finding a 

 good supply of brine. Of one of the borings at Tawas, in the 



