CONTENTS

Page.
[I. Introduction.]
[1. Location and area]5
[2. Statement of work]5
[3. History of development]6
[II. Summary and Conclusions]8
[III. General Character of District]10
[1. Means of access]10
[2. Topography]11
[3. Drainage]14
[4. Flora and fauna]15
[IV. General Geology]16
[1. Outline of Geological history]16
[2. Table of formations]18
[3. Keewatin]18
[General features]18
[Obushkong area]18
[Duncan Lake area]20
[Pigeon lake area]21
[Unfinished areas]22
[4. Laurentian]23
[General features]23
[Relations to other formations]24
[5. Huronian]25
[General features]25
[Basal conglomerate]26
[Greywacke slate and quartzite]27
[Upper conglomerate]27
[Arkose]28
[Structural features and disturbances]28
[Relations to other formations]29
[Origin and correlation]31
[6. Post-Huronian eruptives]32
[Quartz diabase]32
[Character of intrusion and distribution relative to older systems]32
[Macroscopic character]33
[Microscopic character]34
[Local description]36
[Age]37
[Olivine diabase]38
[7. Pleistocene]38
[V. Economic Geology]40
[1. Silver]40
[Distribution]40
[Surface indications]40
[Structure of veins]41
[Composition of veins]41
[Local description]42
[Future possibilities]44
[2. Copper]45
[3. Iron ores]45
[Hematite]45
[Magnetite]46
[4. Asbestos]46
[Distribution]46
[Origin]47
ILLUSTRATIONS.
[1. Frontispiece—View at Foot of Duncan Lake]5
[2. Diagram illustrating the structure of large hills]12
[3. Diagram illustrating geological relationships]16
[4. View looking north from middle of Duncan Lake, 550 ft. hill in distance]20
[5. West Branch Montreal River, near Mosher Lake]22
[6. Fifth portage on West Branch of Montreal River, showing Huronian slate]30
[7. Inclined Huronian Beds, Duncan Lake]32

R. W. Brock, Esq.,

Director Geological Survey Branch,

Department of Mines.

Sir,—I beg to submit the following preliminary report upon work done in the Gowganda Mining Division during the field season of 1908.

I have the honour to be, sir,

Your obedient servant,

W. H. COLLINS.

Chicago, March 8, 1909.

Fig. 1. View at foot of Duncan Lake.

PRELIMINARY REPORT

ON

GOWGANDA MINING DIVISION

DISTRICT OF NIPISSING, ONTARIO

BY

W. H. Collins.