374 REPORT OF NATIONAL MUSEUM, 1904. 



in 1836 has already been noted. Annual reports were issued regu- 

 larly during the period of its existence, but with one or two excep- 

 tions the results can be best summed up in a review of 

 survey of New York, the tinal reports as they appeared in 184:2-4:3. Of 

 these tinal reports, which were issued in quarto form, 

 Mather's, comprising 639 pages, with 46 plates, in part colored, and 

 including a geological map, was one of the most voluminous. 



The tirst geological district, to which Mather was assigned, embraced 



twenty-one counties, extending from the northeast of Washington 



County between lakes Champlain and George southwesterly to the 



Susquehanna River so as to include the counties of 



Ne a w h York Work ta Washington, Saratoga, Schenectady, Schoharie, and 



Delaware, and all of the State east and south of this line. 



Mather thought to have recognized seven periods of elevation and 

 disturbance of the strata, exemplified in the district assigned to him. 

 These he described as follows: 



First. One preceding the laying down of the earliest fossiliferous 

 rocks, which gave rise to the primary Highlands of the v Hudson and 

 the primary mountains of Saratoga and Washington counties. On this 

 he found the Potsdam and Calciferous sandstones and black limestone 

 resting unconformably. 



Second. One which preceded the deposition of the Helderberg 

 limestone, which he found lying unconformably on the upturned ear 

 Her rocks. This manifested itself mainly in the Hudson Valley and 

 included the Highlands and Westchester County. 



Third. One subsequent to the deposition of the rocks of the Onta- 

 rio division, the effects of which he thought to recognize from Green 

 Pond Mountain through Bellevale Mountain, Goose Pond, Sugar Loaf, 

 and Skunnemunk Mountains, and along the Shawangunk Mountains. 



Fourth. One subsequent to the deposition of the Catskill division 

 and even the coal formation. This disturbed all the pre-existing rocks 

 in New York east of the Delaware. To it he ascribed the bending 

 and wrinkling of the coal formations in Pennsylvania, Maryland, and 

 Virginia. The era of disturbance was regarded as between that of 

 the coal and the New Red sandstone. 



Fifth. A period of disturbance at the end of the deposition of the 

 Long Island division and before the deposition of the Quaternary. 



Sixth. A period between the drift and Quaternary by which the 

 land, without deformation, was lifted to about the level of the Qua- 

 ternary formations. 



Seventh. A period after the deposition of the Quaternary by which 

 a large part of the land was lifted 100 feet above the level of the 

 oceanic waters. 



He thought, also, to recognize four periods of metamorphie agency, 

 though, singularly enough, his metamorphism was that of contact by 



