Massive Crystalline Rocks. 167 



schist or slate has been mentioned on page 24, vol. xx. Am. Jour. Sci.) 

 These facts are all in favour of the conclusion that the norite was 

 once a stratum conformable to the Peekskill limestone areas. 



(3) Vicinity of the Verplanck Limestone belt. — The Yerplanck 

 limestone belt follows the border of the river from a point just 

 north of the foot of Broadway, and has the usual strike for the 

 county, north-eastward. Like the Cruger limestone area, it has, on 

 the landward side, with a small exception, a border of ordinary mica- 

 schist or micaceous gneiss, a fine-grained arenaceous rock, the fel- 

 spar of which is mostly orthoclase. This schist extends to the point 

 marked d on the map : at c the rock is massive norite, but no junc- 

 tion of these two rocks is here in sight. 



The exception referred to is at the south-west extremity of the 

 belt on the river. Here there lies against the eastern side of the 

 limestone a great mass of greyish or brownish-black rock of the 

 Cortland series. It is mostly pyroxenite, moderately coarse in grain, 

 but varies to a kind in which the augite individuals are half an inch 

 broad, and, on the other hand, to a fine-grained variety ; and it con- 

 tains, besides augite, a little hornblende, quartz, calcite, and apatite. 

 But portions of the mass consist of coarsish hornblendite ; and a 

 small part of micaceous augite-norite ; and there are also broad and 

 narrow bands of very fine-grained black hornblendic mica-schist, not 

 showing well a schistose structure, part of which are conformable in 

 strike and dip with the beds of the limestone, while others are in 

 other positions. All the material is very pyrrhotitic. Besides, it 

 contains the remarkable limestone breccia, of which a portion three 

 feet square is represented on p. 111. 



This singularly-constituted mass shows no appearance that looks 

 like a subdivision into dykes or veins, except in the bands of horn- 

 blendic mica-schist ; one of these bands has a border of the mica- 

 ceous augite-norite just mentioned. In the limestone just north of 

 tliis mass, facing the river, occur the supposed dykes or veins 

 mentioned on page 111. Some of them consist of pyroxenite; 

 others of coarsish hornblendite; very fine-grained hornblendic rock 

 looking like hornblende schist (Ae) ; very fine-grained hornblendic 

 mica-schist ; augite-norite. 



As already admitted, there is here abundant evidence of a former 

 plastic state in at least part of this augitic and hornblendic material. 

 Still, there are strong reasons for questioning the idea of its deep- 

 seated origin. 1. The variety in the constitution of the mass border- 

 ing the litaestone and in the supposed dykes or veins is very unlike 

 what is ordinarily found in regions of igneous eruption. 2. The 

 supposed veins or dykes are for the most part conformable with the 

 bedding of the limestone, and partake in its flexures, just as if they 

 had been originally beds alternating with the limestone depositions. 

 3. The impregnation of the limestone along the junctions with 

 pyroxenic or hornblendic material, sometimes minute crystals, looks 

 as if it may have been in part at least a result of mixture attending 

 original deposition. 



Further (4), there is the decisive fact that these intercalated masses 



