University of Washington Publications in Geology The Geology of the San Juan Islands

Cover

Introduction

Location and Area of the Region
Field Work and Acknowledgments
Bibliography
Outline of the Geography and the Geology

Topography

Relief
Islands
Channels
Drainage
Culture
Climate and Vegetation

Descriptive Geology

Sedimentary Rocks
   General Character
   Devono-Mississippian Systems
      Orcas Group
         Principal Features
         Lithology and Structure
         Age and Correlation
   Pennsylvanian-Permian Systems
      Leech River Group
         Principal Features
         Lithology and Structure
         Age and Correlation

Triassic System

Haro Formation
   Principal Features
   Lithology and Structure
   Age and Correlation
Lower Cretaceous System or Series
   Spieden Formation
      Principal Features
      Lithology and Structure
      Age and Correlation
Upper Cretaceous System or Series
   Nanaimo Series
      Principal Features
      Lithology and Structure
   Age and Correlation
Eocene System or Series    Chuckanut Formation
      Principal Features
      Lithology and Structure
      Age and Correlation
Quaternary Systems

Igneous Rocks

General Statement
Fidalgo Formation
   Petrographic Details
   Age Relations
Eagle Cliff Porphyrite
   Petrographic Details    Age Relations
Turtleback Complex
   Dunites of the Fidalgo Formation
   Eagle Cliff Porphyrites
   Wark Gabbro-Diorite
   Colquitz Quartz-diorite
   Diorite Porphyrite
   Rhyolite Porphy
   Acid Off-Shoots
   Lamprophyric Off-Shoots
   Age Relations

Structure

Historical Geology

Paleozoic Era
   Devonian Period
   Mississippian Period
   Pennsylvanian Period
   Permian Period
Mesozoic Era
   Triassic Period
   Jurassic Period
   Lower Cretaceous Period or Epoch
   Upper Cretaceous Period or Epoch
Cenozoic Era
   Eocene Period or Epoch
   Oligocene Period or Epoch
   Miocene Period or Epoch
   Pliocene Period or Epoch
Quaternary
   Pleistocene Period or Epoch
   Recent Period or Epoch

Mineral Resources

Limestone
Clay and Cement Materials
Gravel
Feldspar
Coal
Chromite
Building Stone
Water Resources

Areas of the San Juan Islands

Index (omitted from the online edition)

Map

Plate I. The Cone Islands

Plate II. (Upper) The eastern lobe of Orcas Island as seen from Cypress Island. (Lower) Eagle Cliff, Cypress Island

Plate III. Looking eastward from Mount Entrance

Plate IV. Looking up the shore of East Sound from a point near the entrance to Obstruction Pass

Plate V. (Upper) Looking northeastward from Mount Constitution. (Lower) Looking northwestward from Mount Constitution

Plate VI. (Upper) Contorted chert belonging to the Orcas group, Orcas Island. (Lower) Chert belonging to the Orcas group, Orcas Island

Plate VII. (Upper) Devonian brachiopods in the Orcas Lime Quarry, Orcas Island. (Lower) Diallagite and hornblendite occurring as thin parallel stringers in the gabbro-diorite

Plate VIII. (Upper) Richardson, Lopez Island. (Lower) Looking eastward from Lookout Mountain

Plate IX. A storm on the Rosario Strait

Plate X. Looking northward from Obstruction Island

Plate XI. Aucella crassicollis Keyserling from the Spieden formation

Plate XII. Fossils from the Spieden and Haro formations

Plate XIII. The view across the islands as seen from the southwest slopes of the Turtleback Range

Plate XIV. (Upper) Looking northwestward from the slopes of Mount Constitution. (Lower) Honeycomb sandstone on the Sucia Islands

Plate XV. (Upper) Upper Cretaceous rocks along the north shore of Orcas Island. (Lower) A limestone ledge on the shore of East Sound, at the Foot of Mount Entrance

Plate XVI. (Upper) Point Disney, Waldron Island, showing the immense conglomerate bed overlain by fossiliferous shaly sandstone. (Lower) The Point Disney conglomerate

Plate XVII. Fossils from the Nanaimo series and the Leech River group

Plate XVIII. (Upper) The sandspit and lagoon at Argyle, San Juan Island. (Lower) The Upper Cretaceous rocks at Point Thompson, Orcas Island

Plate XIX. (Upper) Ellipsoidal Eagle Cliff porphyrite at the east side of Davis Bay, Lopez Island. (Lower) Ellipsoidal Eagle Cliff porphyrite near Cape St. Mary, Lopez Island

Plate XX. (Upper) Turtleback Mountain and Orcas Knob as seen from the entrance of West Sound. (Lower) Mount Baker as seen from Friday Harbor, San Juan Island

Plate XXI. (Upper) Roche Harbor, San Juan Island. (Lower) One of the quarries of the Tacoma and Roche Harbor Lime Company, Roche Harbor

Plate XXII. (Upper) Feldspar rock deposit at Deer Harbor, Orcas Island. (Lower) Feldspar rock deposit at Deer Harbor, Orcas Island

Fig. 1. Table of formation

Fig. 2. Outline map of James Island

Fig. 3. Outline map of the Barnes and Clark group of islands

Fig. 4. Outline map of Waldron and Skipjack Islands

Fig. 5. Outline map of Stuart, Satellite, and Johns Islands

Fig. 6. The Argyle Lagoon and sandspit

Figs. 7, 8 and 9. Three stages in the evolution of the Argyle Lagoon

Fig. 10. The lagoon and sandspit at the north end of Blakeley Island