AMERICAN JOURNAL OF SCIENCE. 
[THIRD SERIES.] 
Art. LIV.— Geological relations of the Limestone Belts of West- 
chester County, New York; by JAMES D. Dana. Witha map 
(Plate XIX).* 
4. Southern Westchester County and Northern New York Island. 
In the account, on former pages of this memoir,t of Southern 
Westchester County and the adjoining part of New York or 
Manhattan Island, many facts of general interest were omitted. 
e developments which have been announced have given the 
region great geological importance, since they. prove, on evi- 
ence both stratigraphical and paleontological, that the lime- 
Stones, gneisses and mica schists are part of the long north-and- 
south line of the Green Mountain formations, and also part of 
the Lower Silurian series which spread westward over the con- 
tinent.{ I propose here to describe, more fully than has been 
. done, the positions and relations of the limestone areas, and the 
flexures in these and the adjoining rocks. Toward this end 
* For the earlier parts of this memoir, see pages 21, 194, 359 and 450 of the 
last ae 
West of the chief line of the Green Mountains. 
Am. Jour. Sc1.—Tuinp Series, VoL. XXI, No. 126.—Junn, 1881. 
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