I46 NEW YORK STATE MUSEUM 



and south of Port Henry and as much to the west and is bordered 

 by bathylithic masses of syenite and granite. Of this particular 

 locality he makes the following mention : 



Along the Delaware and Hudson Railroad tracks on the lake shore north 

 of Port Henry where there is an irruptive contact of gabbro and basic syenite 

 and limestone one can see the igneous rock tonguing out into the limestone 

 and apparently pinched off at times by the dynamic disturbances. While it is 

 entirely possible that the hornblendic rocks have been derived from aluminous 

 bands in the original sediment, which might yield greater or less amounts of 

 hornblende, yet we are dealing with a district in which are numerous intru- 

 sions of gabbro and basic syenite and where apophyses are abundant. The 

 marked plasticity of the limestone under pressure tends greatly to disguise 

 the relationship and to render a demonstration difficult. Igneous phenomena 

 and their expiring effects must have been very general and have probably 

 occasioned widespread recrystallization. Undoubtedly they have set in migra- 

 tion many heated solutions. 



The limestone at times becomes extremely small in amount and may be 

 represented by little more than calcareous streaks amid more siliceous rocks, 

 such as mica schist and quartzite bands. The more resistant silicates having 

 been involved in a plastic medium like calcite have been bent into shapes that 

 seem almost beyond the power of brittle minerals to assume. The presence, 

 however, of the limestone is indicated by the pitted and cavernous 

 weathering. 



Along the lakeside for the first mile or so north of Port Henry 

 the Paleozoic beds alone are exposed, the strata representing a 

 triangular block of which the western edge runs diagonally to the 

 lakeshore and comes out to the lake in a little cove known as Craig 

 harbor. Here they terminate suddenly in a single great fault which 

 brings the Beekmantown beds on the south side in line with the 

 Precambrian on the north side of the cove. The faulted beds dip 

 toward the crystallines at a low angle. The two series are separated 

 by the width of the cove, but the well-marked escarpment on the 

 north side probably corresponds nearly to the plane of the fault; 

 while the interval is represented by brecciated Beekmantown 

 which by its rapid weathering has formed the embayment. A 

 view of the fault-scarp on the north side of Craig harbor is shown 

 in plate 1. This reveals the Grenville limestone in heavy beds 

 resting Upon a gneissic hornblende rock which at a little distance 

 from the contact grades into recognizable gabbro. The contact, 

 therefore, is igneous, but there is nothing to show the intrusive 

 nature of the gabbro in the way of reaction effects upon the lime- 

 stone or of offshoots of the gabbro into the latter. It is very likely 

 that movement has occurred along the contact through underthrust- 

 ing of the block of gabbro, causing the less resistant limestone to 



