DEPARTMENT OF THE INTERIOR CHAPTER I.—INTRODUCTION..............................................10 Scope and date of work done ......................................10 Acknowledgments ........................................................10 MONOGRAPHS Limits of the Menominee area......................................11 OF THE Relations to other iron-bearing areas...........................11 United States Geological Survey Shape and size of the Menominee tongue ..................11 Economic importance of the district .............................11 VOLUME XLVI Previous work in the district .........................................12 Method of work.............................................................12 Classification of formations ..........................................13 Names of the formations ..............................................13 References to Marquette monograph ..........................13 CHAPTER II.—BIBLIOGRAPHY AND ABSTRACT OF LITERATURE.......................................................................13 CHAPTER III.—PHYSIOGRAPHY...........................................47 Topography. .................................................................47 Drainage.......................................................................48 Origin of the Topography. ............................................48 WASHINGTON Pre-Cambrian Topography.........................................49 GOVERNMENT PRINTING OFFICE 1904 CHAPTER IV.—THE ARCHEAN SYSTEM...............................49 UNITED STATES GEOLOGICAL SURVEY Section 1. Quinnesec schists......................................49 CHARLES D. WALCOTT, DIRECTOR Relations to overlying formations. ......................... 49 The southern area. ................................................ 50 Distribution. ................................................................50 THE Topography................................................................50 Composition and structure of the rock series. ............51 MENOMINEE IRON-BEARING DISTRICT OF Lithology.....................................................................51 MICHIGAN Greenstone-schists and associated greenstones...51 Coarse-grained varieties. ...................................52 BY Gabbros and their derived schists ..................52 WILLIAM SHIRLEY BAYLEY Diabases and their derived schists.................53 Diorites and their derived schists....................53 Fine-grained varieties.........................................54 Origin of the schistosity ..................................54 CHARLES RICHARD VAN HISE, Geologist in Charge Basic lavas and their derived schists..............54 Basic tuffs and their derived schists ...............55 Chlorite-schists.......................................................55 Amphibolites...........................................................56 Origin of the basic schists. .....................................56 Acid intrusives and their derived schists. ...............57 Gneissoid granite and granite-gneisses .........57 Porphyries and felsites and their schistose phases............................................................59 Sericite-schists.......................................................59 Interesting localities....................................................59 Sturgeon Falls ................................................59 Little Quinnesec Falls .....................................60 Big Quinnesec Falls .......................................60 Horserace Rapids...........................................60 The western area................................................... 61 WASHINGTON Distribution. ................................................................61 GOVERNMENT PRINTING OFFICE Topography................................................................61 1904 Lithology.....................................................................62 Fine-grained greenstones and their derived schists ............................................................62 CONTENTS. Coarse-grained greenstones and their derived schists ............................................................64 LETTER OF TRANSMITTAL..................................................... 3 Fragmented schists ........................................64 Origin of the rocks......................................................64 OUTLINE OF MONOGRAPH.................................................... 3 Interesting localities....................................................65 Monographs of the USGS Vol. XLVI – Chapters 1-5.1 – Page 1 of 111 Upper Twin Falls.............................................65 Quinnesec fold ...........................................95 Lower Twin Falls.............................................65 Norway fold ................................................96 Fourfoot Falls..................................................65 Aragon fold .................................................96 Section 2. Northern Complex. .................................... 65 Other secondary folds at the southern Distribution. ................................................................65 margin ........................................................98 Topography. ...............................................................66 Secondary folds at the northern margin .....98 Sequence of rocks......................................................66 Interior folds....................................................98 Lithology. ....................................................................66 Thickness...................................................................99 Gneissoid granites..............................................66 Relations to adjacent formations................................99 Banded gneisses. ...............................................67 Relations to underlying Sturgeon Hornblende-schists.............................................67 quartzite..................................................99 Intrusives. ...........................................................67 Relations to overlying Negaunee Acid intrusives ................................................67 formation ..............................................100 Basic intrusives...............................................68 Relations to basal member of the Upper Interesting localities....................................................68 Huronian...............................................100 Relations to other formations................101 CHAPTER V.—THE ALGONKIAN SYSTEM............................. 68 Interesting localities..................................................101 General character and definition.................68 In the northern belt. ..............................................101 Unconformity within the system ..................68 Northeast quarter of sec. 3, T. 40 N., Section 1. Lower Menominee series. ......................... 69 R. 30 W ....................................................101 Succession and distribution ........................69 Northeast quarter of sec. 14, T. 40 N., R. 30 W ....................................................101 Sturgeon quartzite..................................................69 In the central belt..................................................102 Distribution and topography........................................69 Southwest quarter of sec. 22, T. 40 N., R. 30 Lithology. ....................................................................70 Conglomerates. ......................................................70 W..............................................................102 Arkoses and graywackes........................................71 Iron Hill .....................................................102 Quartzite.................................................................71 In the southern belt. .............................................103 Dolomitic quartzite..................................................72 Southeast side of Lake Antoine................104 Veins and dikes in the quartzite..............................72 Southeast quarter of sec. 32 and southwest quarter of sec. 35, T. 40 N., R. 30 W........104 Folding........................................................................73 North and northeast of Quinnesec............105 Thickness. ..................................................................73 Northwest quarter of sec. 9, T. 39 N., Relations to underlying formations. ............................74 R 29 W .....................................................106 Relations to underlying formations. ............................74 Secs. 12 and 13., T. 39 N., R. 29 W.........108 Interesting localities....................................................75 The “rock dam” on Pine Creek....................75 Negaunee formation............................................109 Black Creek ................................................76 Distribution. ..............................................................109 North half of sec. 7, T. 39 N., R. 28 W........77 Lithology...................................................................109 West half of sec. 8, T. 39 N., R. 28 W.........77 Relations to adjacent formations..............................110 Falls of the Sturgeon...................................77 Conclusions from foregoing study. ...........................111 Randville dolomite..................................................79 Distribution and topography........................................79 The northern