Wrangellia (Vancover Island crustal plate)

The beginning of Wrangellia started about 380 million years age. At this time it was a broard, deep oceanic lava plain that supported chains of volcanic islands (island arcs) e.g. Aleutions. This chain move from the tropics to became part of British Columbia by 100 million years age.

Show Wrangellia joining North America (Amimation)

Physiography and Origins of B.C.(presentation)

Cascadia Subduction Zone (Dynamic earth)


Bibliography
  • The Geology of Southern Vancouver Island, A Field Guide. by C.J Yorath and H.W. Nasmith. Published in 1995 by the Pacific Section , Geological Association of Canada. Orca Book Publishers, Victoria, B.C., Canada.
  • West Coast Fossils Second Edition by Rolf Ludvigsen and Graham Beard, published in 2001 by Harbour Publishing, Madeira Park, BC.

Formation of Gabriola Island

Map of Geology of Gabriola Island and area

Gabriola island rocks are made up from the Nanaimo group of sedimentary rocks. The Nanaimo Group is a series of Upper Cretaceous clastic sediment formations desposited in a shallow-to-deep basin between Vancouver Island and the mainland.

Nanaimo Group strata overlie Wrangellia (Gabriola Island is part of this area) to the west, the Coast Belt to the east, and to the southeast they are in fault contact with the San Juan thrust system. The lower one third of the Nanaimo Group is a complex mix of nonmarine alluvial and mostly shallow-marine fine-grained sedimentary rocks, whereas the upper two-thirds is composed of mudstone and thin-bedded sandstone turbidites of dominantly deep-marine origin. This upper section includes conglomerates deposited in submarine fan systems.

Nanaimo rock formations

Gabriola formation

Spray (Mayne) formation

Geoffrey (Galiano) formation

Northumberland formation

De Courcy formation

Cedar District formation

Protection formation

Pender formation

Extension formation

Haslam formation

Comox (Benson) formation