PBTROGRAPHIC GEOLOGY AND DESCRIPTIONS. 221 



Diabase. Basalt . ] 



No. 140. DIABASE (with olivine). 



Second fall of Baptism river. This fall is divided into two parts, and the samples are from the top of the 

 first part of the fall. Dip northwest, but less than further up the river. 

 Ref. Annual Report, is, page 37. 



Meg. A medium-grained, brownish gray basic. 



Mic. The minerals are evident and rather well preserved, though not intact, 

 the thickness of the section being such that they are considerably obscured by the 

 included impurities. In this respect the rock is more like an offshoot from the 

 great Beaver Bay diabase than like the strata with which it is associated. The 

 olivine is much affected by magnetite inclusions, but some of the grains still preserve 

 their power to polarize light, a fact which has not yet been found to prevail in the 

 older Cabotian effusives. 



One section. 



Age. Cabotian. N. H. w. 



No 147. BASALT. 



One of the fine-grained alternating trap-sheets, lying between amygdaloidal sheets about one-fourth mile 

 below the second fall of Baptism river. From the layer which slopes into the river from the left bank at an 

 angle of about 15 toward the west, 15 north. Above this rises a bluff about eighty feet, composed of trap 

 and amygdaloid beds. 



Ref. Annual Report, is, page 38. 



Meg. This rock is hard, fine-grained, but somewhat amygdaloidal in places, 

 with launioutite. 



Mic. The augite and olivine are replaced by ferruginous impurities and can 

 only be identified by their forms. The feldspar microliths cut through the ground- 

 mass in the usual independent manner. 



One poor section. 



Age. Cabotian. N. H. w. 



No. 148. DIABASE (with olivine). 



At the first fall of Baptism river. There is an apparent anticlinal axis, and this rock is from the lowest 

 stratum over which the other strata seem to pass, dipping in opposite directions. The dip changes here from 

 northwest to southeast. This presents a somewhat basaltiform structure. Below the fall the bluffs are about 

 100 feet high. 



Ref. Annual Report, ix, page 38. 



Meg. A medium-grained, dark gray, heavy rock. 



Mic. Presents the usual characters of an olivine diabase, but it also has the 

 ophitic relation between the plagioclose and the augite, i. e., it is lustre-mottled, the 

 latter mineral embracing several crystals of the former. 



Age. Cabotian. 



Remark. This rock is probably the equivalent of Nos. 150 and 141. In the 

 form of an offshoot it probably forms the dike represented by No. 152, and by means 

 of a fault it is also raised to constitute the brink of the first fall of Baptism river, or 



