5§ NEW YORiC STATE MUSEtJM 



The latter have been employed largely in the manufacture of terra 

 cotta. A plant producing this material is located at Tottenville. 

 Fire brick and pressed brick are made at Kreischerville and common 

 brick at Green Ridge. 



Hudson valley. The clays of this region are of great economic 

 value. They are found on either side of the river, as far south as 

 Rockland and Westchester counties, in terraced deposits arranged 

 at elevations up to 300 feet or more above sea level. They are 

 usually overlain by delta sands and gravels with a soil capping. 

 The workable beds attain a thickness in some instances of 100 feet. 

 Thin layers of sand alternate with the clay and the whole series is 

 well stratified. The clay normally has a blue color, but where 

 unprotected by overlying beds it is weathered to yellow, the weath- 

 ering often extending to a depth of 15 feet. The oxidation of the 

 iron components which produces this change is facilitated by the 

 sandy loosely textured nature of the upper beds which permits the 

 percolation of water from the surface. The blue clay is more 

 plastic than the yellow, and both contain from 3 to 6 per cent lime 

 carbonate, thus belonging to the class of marly clays. 



The Hudson river deposits are employed solely in brickmaking. 

 There are over 100 plants engaged in this industry and the annual 

 output amounts to more than 1000 million brick. Some of the 

 leading centers of manufacture are Haverstraw, Croton, Stony 

 Point, Verplanck, Peekskill, Cornwall, New Windsor, Dutchess 

 Junction, Fishkill, Roseton, Poughkeepsie, Kingston, Saugerties, 

 Catskill, Hudson and Albany. 



Lake Champlain. The deposits are somewhat similar to those 

 in the Hudson valley. Terraces occur along the lake from White- 

 hall, at the southern end, to beyond the limits of New York State. 

 They are of variable width, narrowing southward, where the Adi- 

 rondack ridges rise steeply almost from the shore line. At the 

 lower end of the lake the deposits are largely of marine character 

 and were laid down on the receding shores of the sea which invaded 

 the region after the withdrawal of the glacial waters. At Beauport 

 and Port Kent the section shows yellowish brown sand, yellowish 

 brown clay and stiff blue clay, the latter being calcareous. The 

 formation has a thickness of 15 feet. The clays are used for brick, 

 principally around Plattsburg. 



Interior of the State. Clay beds are widely distributed, but 

 their economic utilization is confined mostly to the vicinity of the 

 larger towns and cities. 



