NEWARK ROCKS OF ROCKLAND COUNTY, N. Y. 



29 



south of the Rockland lake landing (&, fig. 4). 100 yards north 

 of the landing (c) a welded contact of fine grained trap resting 

 on highly metamorphosed shale is exposed near the water level in 

 the bed of a small brook. Just north of this, brown sandstone 

 outcrops at a higher level, showing that here again the trap 

 ascends at least 25 and probably 75 feet across the beds. Be- 

 tween these exposures north and south of the landing, the base of 

 the trap seems to be near the water level. The evidence appears to 

 show that there is no change of horizon at the gap just back of 

 the landing. This point is of importance in determining whether 

 or not the gap is located on a fault line. Though not conclusive, 

 the evidence is strongly against the fault hypothesis. 



JO Feet 



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1 I J>\ 1- 



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'V-i-ii-Miio 



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Fig. 3 Basal contact near the powder house one mile south of Rockland Lake landing. 



From Rockland lake landing northward the trend of the shore 

 constantly brings higher beds down to the level of the river. The 

 base of the trap must, therefore, soon be carried below sea level, 

 unless it changes to higher geologic horizons. At the locality 

 last mentioned the contact rises by crossing the beds to an ele- 

 vation of at least 75 feet above the river. (Thence it is in part 

 conformable to the shales and in consequence slowly descends to 

 about 25 feet above the river at the Cosgriff trap rock quarry 

 (d, fig. 4) at Trough Hollow. Whether in this interval of half a 

 mile it changes its horizon is unknown, as the actual contact is 

 not shown. 



