REPORT OF THE STATE GEOLOGIST ON THE MINERAL INDUSTRIES AND GEOLOGY OF VERMONT 1929-1930 SEVENTEENTH OF THIS SERIES GEORGE H. PERKINS State Geologist STAFF OF THE VERMONT GEOLOGICAL SURVEY 1929-1930 GEORGE H. PEinuNs, State Geologist. Director, University of Vermont. CONTENTS ELBRIDGE C. JACOBS, Assistant Geologist, University of Vermont. PAGE PHYSIOGRAPHY OF VERMONT, G. H. CHARLES H. RICHARDSON, Assistant Geologist, PERKINS ..................... 1 Syracuse University. A STUDY OF ALTITUDE AREAS IN VERMONT, H. F. PERKINS ......... 55 CLARENCE E. GORDON, Assistant Geologist, BIBLIOGRAPHY OF VERMONT PETROLOGY, MARION HUBBELL .......... 65 Massachusetts Agricultural College. THE aEOLOGY OF VERMONT OCHER DEPOSITS, FREDERICK A. BURT 107 Miss MARION HUBBELL, Assistant Geologist, MOUNT MONADNOCK III VERMONT, J. E. Worr ................... 137 Brooklyn, N. Y. LIST OF VERMONT MINERALS, G. H. PERKINS ..................... 151 FREDERICK A. BURT, Assistant Geologist, THERE GEOLOGICAL SERIES IN NORTHWESTERN VERMONT, H. W. Mechanical and Agricultural College of Texas. MCGERRIGI,E ............................................... 179 E. J. Fovus, Assistant Gologist, AREAL AND STRUCTURAL GEOLOGY OF SPRINGFIELD, VT., C. H. Rid- Rochester University. AEDSON................................................... 193 GEOLOGY OF GRAS-TON AND ROCKINGIIAM, VT., C. H. RICHARDSON .... 213 CONTRIBUTING GEOLOGISTS GEOLOGY OF EAST MOUNTAIN, MENDON, VT., E. J. FOYLES .......... 239 COMPRESSED MICA RESEMBLING GRAPTOLITES, E. J. FOYLES ........ 252 JOHN E. Woui, MINERAL RESOURCES OF VERMONT, G. H. PERKINS ................. 253 Harvard University. H. F. PERKINS, University of Vermont. H. W. MCGERBIGLE, Dartmouth College. LIST OF FIGURES PAGE 1—Map of Vermont showing surveyed areas 58 2—Map showing location of ocher beds in Vermont ............ 110 3—Section south of Forestdale ............................... 118 4—Section showing manganiferous clay ....................... 119 5—Generalized section of ocher area .......................... 120 6—Map showing position of ocher beds near Brandon .......... 122 7-01d mine drift, South Wallingford ......................... 125 8—Map showing position of ocher beds and kaolin near Ben. nington............................................... 125 9—Cross section of Rockwood and Vermont Company's kaolin beds.................................................. 126 10—Mount Monadnock, Vermont ............................... 137 11—Map showing position of syenite hills in Canada and New England.............................................. 138 12—Monadnock area in Vermont ............................... 141 13—Philipsburg series central sequence ....................... 182 14—Section east from Highgate Springs ........................ 183 15—Section at boundary line .................................. 190 16—Areal map of Springfield, Vt. .............................. 192 17—Cross section of terranes in Springfield, Vt . ................ 193 18—Cavendish schist and Gassetts schist, Springfield, Vt . ....... 197 19—Conglomerate dipping west, Springfield, Vt . ................ 200 20—Limestone and phyllite schist, Springfield, Vt . .............. 203 21—Quarry, granite-gneiss. Zenolith of Cavendish schist, Spring- field, Vt . ............................................. 205 22—Closely folded gneiss and schist, Springfield, Vt . ............ 206 23—Outcrop of metadiabase, Springfield, Vt . ................... 209 24—Much altered metadiabase, Springfield, Vt . ................ 210 25—Areal map of Rockingham, Vt . ............................ 214 26—Cross section in Rockingham, Vt. .......................... 215 27—Areal map of Grafton, Vt. ................................. 217 28—Cross section in Grafton .................................. 218 29—Anticline, phyllite sehist, Rockingham, Vt . ................. 226 30—Pegmatite dike cutting granite-gneiss, Bull Hill, Grafton, Vt 232 31—Djabase dike cutting Bellows Falls gneiss .................. 234 vi REPORT OF THE VERMONT STATE GEOLOGIST PAGE 32—East Mountain area showing section lines and topography... 238 33—Mendon between stations 7 and 8. Shows two stages in Green Mountain orogeny. Granite intrusion between two slopes 240 34—West-East section at north end, along line A-B .............. 241 35—East-West section along line B-A .......................... 242 36—West-East section through East Mountain along line C.D . - 242 37—West-East section through East Mountain along line E-F . - 243 38—West-East section through East Mountain along line G-H . - 243 39—West-East section along line I-J ........................... 244 STATE OF VERMONT OFFICE OF STATE GEOLOGIST BURLI NGTON To His Excellency, John E. Weeks, Governor: Sir:—In accordance with Act 405 of the General Laws of Vermont I herewith present my Seventeenth Report as State Geologist. This Report includes a discussion of various geological fea- tures as found in Vermont, written for this volume by a number of competent geologists, as is shown in greater detail in the Intro- duction which follows. As heretofore in these Reports, articles of value to students of Vermont Geology are presented. Respectfully submitted, GEORGE H. PERKINS, State Geologist. DECEMBER 1, 1930. INTRODUCTION This is intended only as a brief summary of what is contained in the following pages. As has been noticed in preceding volumes of these Reports the geology of \Termont is for the most part exceedingly complicated and can be clearly understood only after extended and careful study. To elucidate as far as possible the history of the rocks of the Green Mountain mass as well as that of the rest of the State and to present the results and conclusions reached by such study is the main purpose of these Geological Reports, which have been issued biennially for over thirty years. As far as it has been attainable, all that could he found that helped to a good understanding of Vermont geology has been included in the volumes published. As in most of the former volumes, so in this, the aid of stu- dents of Vermont geology has been sought and, as the contents of the volumes shows, in many cases obtained, so that in a file of these Reports most that has been published in respect of Vermont geology can be found, in most articles as original contributions, in some as reprints. "The Bibliography of Vermont Petrology," by Miss Hubbell, shows in a very useful fashion what has been written upon this subject; besides this considerable material not within the scope of Miss Hubbell's paper is yet unpublished. As far as possible it is desired that the discussions in these Reports shall be as free from technicalities as may be so that the various papers included shall be as intelligible as they can he to readers who have little geological training. In some cases the use of technical terms is unavoidable, for none other are in existence. In the first paper on "The Physiography of Vermont," by the Geologist, the physical features of the State, lakes, mountains, rivers, etc., are more or less fully described, the object, as in- dicated in the paper, being to interest Vermonters in the more obvious features of the State and to some extent to understand how they came to be as we now see them. Connected with the surface features of Vermont, really form- ing an important part of them, are the altitudes of towns in the State. Some idea of the great irregularity seen in the surface of x REPORT OF THE VERMONT STATE GEOLOGIST Vermont is shown by the facts given in the second paper, by H. F. Perkins, which presents a summary of a careful study of the surface, as determined by the U. S. Topographical Survey now PHYSIOGRAPHY OF VERMONT well towards completion. G. H. PERKINS Miss Marion Hubbell has placed all future students of Ver- mont geology under obligation by means of her "Bibliography of In the Eleventh Biennial Report on Vermont Geology, 1917- Vermont Petrology." Beds of ocher are found in several localities 1918, the writer published an article having the above title. As in the State and a very interesting and complete account of them there has been considerable demand for information upon this will be found in Professor Burt's paper. Professor Wolff has subject and as the volume above mentioned has for several years kindly given permission to reprint his paper on a "Monadnock been out of print, it has seemed best to give in this Report a in Vermont." As a supplement to a paper on "The Rocks of revised and enlarged republication of the former article. The Physiography of Vermont means, in this article at least, Vermont," published in the last Report, the Geologist here gives the Surface Geology, that which most obviously appears as one a brief account of "The Minerals of Vermont." Professor Mc- looks about him and sees the mountains, hills, rivers, lakes, plains Gerrigle adds to our knowledge of the geology of northwestern and all other natural features that may be spread before him. Vermont by his article which gives the results of his recent study It is the most recent phase of the geological history of the State. of the region, the geology of which is by no means well under- But if one wishes to know why these features are what they are, stood, or until lately has not been. Professor C. H. Richardson how they have come to be what he sees, he will not be content with a merely superficial investigation. The why is this or that continues his excellent study of Vermont geology southward into part of the landscape evidently involves vastly more than what is Springfield, Grafton and