296 THE GEOLOGY OP MINNESOTA. 



[Diabase. Qabbro. 



No. 273. DIABASE. 



From a dike running N. 60 E., crossed by the vein No. 272, situated in S. W. J^ sec. 32, T. 64-7 E. 

 Ref. Annual Report, ix, page 65. 



An ordinary diabase, with quartz and much apatite, considerably altered, spotted 

 with reddish brown. 

 One section. 



Age. Cabotian(?) N. H. w. 



No. 274. GABBRO. 



From near the trail to Parkerville.* About three-quarters of a mile north of the lake shore, near the north 

 line of sec. 32, T. 64-7 E. This rises in a low hill, just north of the point where the trail runs over a stony beach 

 fifty-two feet above lake Superior. 



Ref. Annual Report, ix, pages 66, 69, 70. 



Meg. Coarsely crystalline with porphyritic glassy feldspars. Sample much 

 decayed. Probably a hornblende gabbro, like the rock at the extremity of Pigeon 

 point (No. 291). The section is worthless for examination. 



Age. Cabotian. N. H. w. 



No. 275. DIABASE (with olwine). 



From the dike at the brink of Pigeon River falls, running north 50 E. 



Ref. Annual Report, ix, page 66; Annual Report, x, page 140; American Association for the Advancement 

 of Science, vol. xxx, page 163. 



This rock is an ordinary ophitic diabase, with considerable magnetite. 

 One section. 



Age. Cabotian (?) N. H. w. 



No. 276. DIABASE (with olivine). 



From a dike just below Pigeon River falls, running east 10 north. These two dikes seem to converge 

 toward the hill where No. 261 was obtained. 



This rock is not different from No. 275, as evinced by the thin section with that 

 number. Yet the specimen bearing that number is coarse and rough with the ophitic 

 augites. N. H. w. 



No. 277. DIABASE. ( Porphyritic. ) 



" Porphyritic basalt, from a small island west of Governor's (or Susie)f island, south of the island which 

 furnishes No. 269. This island is caused by this dike, but has the country quartzyte on the flanks. On the east 

 and north side, it dips a little east of south, or as the slates at Pigeon River falls. It rises about twenty-five feet." 

 This is from the island called Oley island, in the northwest corner of sec. 5, T. 63-7 E. 



Ref. Annual Report, ix, page 66. 



Meg. A fine or medium-grained diabase, black and heavy and apparently some- 

 what altered. It contains small porphyritic plagioclases and a few reddish areas. 

 No section. 

 Age. Cabotian(?) u. s. G. 



* Parkerville was the name given originally to a settlement at the mouth of Pigeon river. It embraced but two or three 

 buildings and has now entirely disappeared. 



t The islands of the Lucille group have received two sets of names ; one by Dr. Hanchett, state geologist in 1864, and the other 

 by the officers of the U. 8. Lake Survey in 1870. The former having priority have th& first claim to acceptance. 



