GEOLOGICAL AND NATURAL HISTORY SURVEYS. 307 



determined satisfactorily the age of certain limestones, slates, and 

 sandstones in the Connecticut Valley. 



Later interpretations, by Professor Hitchcock included, after 1878, 

 the study of the crystalline schists which attracted considerable at- 

 tention. Locally the plan of measuring sections in New Hampshire 

 and Vermont in east and west directions was resumed. Dartmovith 

 College came into possession of the collections amassed originally for 

 the State agricultural college and authorized additional work upon 

 them, increasing the number of the sections from 13 to 18, one of 

 which lay chiefly in Quebec and another in Massachusetts. Professor 

 Hitchcock was constantly revising the conclusions of tlie earlier 

 reports and collecting new specimens of all sorts up to 1908, when 

 his official connection v/ith the college ceased. Complete catalogues 

 of all the sectional and petrographical collections, arranged in accord- 

 ance with the latest conclusiofts, were left behind in the cases accom- 

 panied by colored profiles and a large relief map. The localities of 

 all the specimens upon the sections are indicated both upon the 

 profiles and accompanying quadrangles. 



Some of the later conclusions are the following: 



1. The Green Mountain axis is clearly proved to be post-Cambrian. 

 Kelated to this is a short range of gneiss from Halifax to Reading, 

 Vermont. The Connecticut-lMerrimack watershed is underlaid by a 

 well -characterized gneiss, connected in Massachusetts with what some 

 call Algonkians, and passing into Maine north of the White Moun- 

 tains. Others similar are the Winnipiseogce range running into 

 western Maine, the Manchester range cutting across the southeast 

 part of New Hampshire, and short, parallel ranges in Essex Coimty, 

 Massachusetts. 



2. The hydromica-chloritic formations of middle Vermont and the 

 upper Connecticut Valley may be Cambrian or Ordovician. 



3. The mica schists, partly calciferous, of eastern Vermont, carry 

 the graptolites of the lower Trenton both in Vermont and Canada, 

 and others are closely related to some of the Montalban areas. 



4. The areas of the upper Silurian upon the Connecticut and its 

 tributaries have been enlarged and multiplied, and pass into the 

 Devonian. 



5. Patches of the Carboniferous are anticipated. 



6. Igneous protrusions occur at several horizons all through the 

 Paleozoic. 



NEW JERSEY. 



FIRST SURVEY UNDER HENRY D. ROGERS, 1835-183 7. 



Organization. — As early as 1832, Gov. Peter D. Vroom, in his 

 message to the legislature, advocated the establishment of a geological 



