258 THE GEOLOGY OP MINNESOTA. 



[Diabase. 



alteration products. Some secondary quartz is also present. At one edge of the 

 slide is a small area which probably represents part of one of the fragments noticed 

 in the hand specimen. It is composed of quartz, feldspathic material, augite, and 

 confused alteration products. The quartz is in poikilitic areas. 



One section. 



Affe. Cabotian. u. s. G. 



No. 207. DIABASE ( with olivine) . 



From a dike about 200 feet wide cutting the rock No. 203. There are six such dikes within the distance 

 of a mile. They run E. 15 S.; a short distance east of Grand Marais. 

 Ref. Annual Report, ix, page 53. 



Mey. Coarse, dark-gray diabase. 



Mic. Similar to No. 199, of which it probably is a cotemporary. The large 

 augites embrace the earlier feldspars in an ophitic manner. 



One section. 



Age. Cabotian; probably an apophysis of the great gabbro outbreak which 

 exists in full force in the hills further north. N. H. w. 



No. 208. DIABASE (with olivin?.). 



East of Grand Marais; just beyond the mouth of the third little creek represented on the Lake Survey 

 chart. 



Ref. Annual Report, ix, pages 53, 54, 56. 



Meg. Two rocks, or two forms 'of the same rock, are designated by this number. 

 One is tine grained, brown and heavy, outwardly resembling the Two Harbor rock 

 (compare Nos. 117 and 176), but the other is coarser and has a greenish-gray color. 

 It is less heavy than the former. 



Mic. These are both essentially olivine diabases, but the finer-grained one con- 

 tains much more olivine than the other. 



Two sections. 



Remark. " This rock occurs much like a dike, at first, with perpendicular 

 jointage, or basaltic structure in beds, but soon larger bedding, crossing these, cuts 

 it and causes the rock to all appear bedded. This is fine grained and brown, and 

 is about twenty-five rods from the last of the dikes already mentioned. This becomes 

 a bedded rock like similar beds seen before, having sometimes the appearance of the 

 Two Harbor rock. It slopes toward the water. Just beyond the mouth of the third 

 little creek (on the Lake Survey chart) these beds become disturbed and brecciated, 

 and even tipped in the other direction (southwest), and are crossed by a dike of 

 doleryte, like No. 207, about eighteen feet wide. Previous to this (further west), 

 they show patches amygdaloidal ; but just on the east of this dike there is much 

 amygdaloid with laumontite. Just before reaching the mouth of the fourth creek, 

 another dike like No. 207 crosses these beds, running in the same direction as those 



