The next up in our Drunk on Geology series is the Volcanic Hills Magma Red from the Volcanic Hills Winery. The Volcanic Hills Winery is located in the Okanagan Valley, BC, Canada.
"Since 1978 my family and I have been growing grapes in the Okanagan Valley. Our winery is situated on the south eastern slope of a 60 million year old dormant volcano - Boucherie Mountain, which inspired the name "Volcanic Hills". "
|The north face of Mount Boucherie. Image courtesy of Stéphane Charette and available on Wikipedia. |
The Okanagan Valley is what is known as a rift valley. This is where essentially the plate starts to tear itself apart. Think of pulling apart some raw dough. As the center area stretches out it starts to get thinner. This thinning of the crust causes the hot mantle down below the crust to come closer to the surface. As the crust gets thinner, the hot mantle is then able to heat up the rocks near the surface, melting them and forming volcanoes. That is what happened in the Okanagan Valley.
|Geology of the Okanagan Valley rift zone. Image courtesy of Okanagan Landscape.|
Starting ~57 million years ago, the rifting occurred along the Okanagan fault that runs up the center of the valley. Erupting within the valley around 50 million years ago are several volcanoes including Knox Mountain, Dillworth, as well as the afore mentioned Mount Boucherie. Mount Boucherie is a type of volcano known as a stratovolocano. A stratovolcano is a volcano that slowly builds itself up over time with layers of lava flows and ash layers intermixed together. Typically these are more felsic in composition (higher quartz content), meaning that they are more explosive in nature. This remains true for Mount Boucherie, which is mainly composed of rhyolite (a very thick, high silica/quartz content, felsic volcanic rock) and andesite (an intermediate, medium silica/quartz content, volcanic rock). These volcanic rocks formed likely during explosive volcanic eruptions within the area. However, since Mount Boucherie hasn't erupted in several millions of years, and isn't likely to erupt again, it is considered an extinct volcano.