REPORT OF THE DIRECTOR I916 297 



influence of heat and pressure and consequently is found in meta- 

 morphic areas that accompany mountain-making and igneous intru- 

 sions. In New York State this form occurs in the Adirondacks in 

 the north and the Taconic-Highlands region in the southeast. It is 

 thus of early geological age, since the period of crustal movement 

 and metamorphism in the Adirondacks was terminated before the 

 beginning of Cambrian time, and in southeastern New York was 

 completed with the Paleozoic. 



In the Adirondack region the crystalline limestones useful for 

 quarry materials are most abundant on the western border in 

 Jeflferson, Lewis and St Lawrence counties where they occur in 

 belts up to 4 or 5 miles wide and several times that long, interfolded 

 and more or less intermingled with sedimentary gneisses, schists 

 and quartzites. They are found in smaller and more irregularly 

 bounded areas in Warren and Essex counties on the eastern side, 

 but have little importance elsewhere. The serpentinous marbles 

 that have been quarried at different times belong to the same series. 

 The marbles of the Adirondacks comprise both calcite varieties 

 with little magnesia, and magnesian varieties ranging into true 

 dolomites, with 40 per cent of more of magnesium carbonate. No 

 definite relations seem to underlie their respective occurrence and 

 both calcic and dolomitic marbles are found in the same belts and 

 sometimes in close association. 



The southeastern New York marbles occur in belts which follow 

 the north-south valleys that parallel the ranges of hills to the east 

 of the Hudson from Manhattan island north to Columbia county. 

 On the west side of the river in Orange county are found a few 

 smaller belts. In this region the marbles mostly belong to the 

 dolomite class. They are interfolded with schists and quartzites, 

 the whole series having steep dips like those of strongly com- 

 pressed strata. The geologic age of the southern belts may be Pre- 

 cambrian, but on the north and east within the Taconic area they 

 are perhaps Paleozoic. Individually the marbles range from very 

 coarse to fine-grained rocks, white to grayish in color, rarely show- 

 ing color pattern and are either magnesian marbles or- true 

 dolomites. 



Some compact granular limestones that are capable of taking a 

 good polish are classed as marbles in the trade. They lack the 

 brilliancy of the crystalline varieties, but may possess an attractive 

 color or a variety of pattern such as is lent by the presence of fos- 

 sils. In some instances a subcrystalline texture has been developed 

 as a result of solution and precipitation of the carbonates by ground 



