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The Occurrence of Algonkian Rocks in Vermont and the Evidence for their Sub-Division.

Published with permission of the Chief Geologist, United States Geological Survey.

Contents.

Geography.
Topography.
Geology.
- Outline of the views previously held regarding the structure and age of the Green Mountains.
The Problem Outlined.
Reasons for Refering these Rocks to the Algonkian.
The Upper or Mendon Series of the Algonkian.
The Lower or Mount Holly Series of the Algonkian.
Evidence of Discordance Between Mount Holly and Mendon Series.
Review.

Geography.

The area of the Pre-Cambrian rocks forming the subject of this paper^[1] is quite limited in comparison with the probable extent of these rocks in Vermont. Personal reconnaissance work has detected them existing from the town Stratton on the south to Rochester on the north, a distance of fifty miles. In only a part of this area has detailed work been done, viz.; from Weston to Chittenden. On the east the district is bounded by Plymouth Valley; on the west by Rutland Valley, an area of about 240

↑ The work, of which this paper forms a partial result, was done under the immediate supervision of Mr. Raphael Pumpelly, then in charge of the Archæan Division of the United States Geological Survey, to whom my greatest thanks are due for useful counsel and advice. It is not to be understood that he is necessarily in perfect accord with me in any views advanced here.

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[1] The work, of which this paper forms a partial result, was done under the immediate supervision of Mr. Raphael Pumpelly, then in charge of the Archæan Division of the United States Geological Survey, to whom my greatest thanks are due for useful counsel and advice. It is not to be understood that he is necessarily in perfect accord with me in any views advanced here.

[1]