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The Geology of Mayne Island
November 24, 2021 @ 7:00 pm - 8:00 pm
During the event, Rebecca mentioned a drilled well information resource. The web resource for information about drilled wells can be found here: Groundwater Wells and Aquifers – Province of British Columbia (gov.bc.ca)
U of Calgary PhD student Rebecca Englert presents findings from research on the sedimentary rocks that make up Mayne Island.
Rebecca has a B.Sc. in Integrated Science (2015) from McMaster University and a M.Sc. in Geology (2017) from the University of Calgary. She is currently in the final year of completing a Ph.D. in Geology at the University of Calgary where her research focuses on seafloor processes and how they are recorded in deep-water sedimentary rocks. For her M.Sc. and Ph.D. she has spent several months doing fieldwork on the Gulf Islands as well as in Patagonia, Chile.
About the Research
Since 2013, graduate students and researchers from the Department of Geoscience at the University of Calgary have been studying the geology of the Gulf Islands. Their work has focused on the sedimentary rocks that make up Hornby, Denman, Gabriola, Galiano, Mayne, and Saturna Islands. The group of researchers visits the islands every summer and spends weeks exploring their beautiful coastlines. Through detailed mapping and lab analysis, they now have a better understanding of how the rocks that make up the Gulf Islands formed and their ages. On November 24th, Rebecca will be giving a presentation to share some of the findings of that research. The presentation will focus on the geology of Mayne Island, although rocks with very similar ages and histories also make up the other Gulf Islands.
Our Rocky Island
Rock types that make up Mayne Island include conglomerates, sandstones, and mudstones, which can be seen in cliff faces and in the intertidal zone along the island’s shoreline. These rocks were formed millions of years ago, at hundreds of meters below sea level, and from sediments such as sand, gravel and mud that made up an ancient seafloor. Underwater channels, which are similar to the river channels like the Fraser River seen on land, were present on this ancient seafloor and their courses controlled the distribution of different types of sediment. These sediments were eventually buried and compacted into rocks and later tilted, uplifted, and eroded to form the series of islands (the Gulf Islands) present in the Strait of Georgia today.
The oldest rocks on Mayne Island are 80 million years old and are found on the southwest shore including those that make up St. John’s Point. Rocks become progressively younger to the northeast and those seen on the northeast shore of the island, such as at Georgina and Edith Points, are 68 million years old. This means that the rocks on Mayne Island span 12 million years of Earth’s history! We’ve been using this incredible record of the past to understand the geologic history of western British Columbia and seafloor processes such as the burial and storage of organic carbon (dead plant matter) and its effect on climate.
Learn more about this interesting research by joining our Zoom event.