Layering is expressed as thin layers separated by thick layers
exposed along a weathered fault scarp. The compositions of the
thick and thin layers are geochemically very similar. The thin
layers represent veins generated during crystallization of the
lava. The thin layers formed when the molten material contracted
(shrunk) while cooling. Material was allowed to flow into the
cracks formed by cooling. The material in the cracks further
fractured when it cooled, and liquid material was allowed to enter
the veins. The resulting rock was formed with a slightly different
composition. The altered thin layers weather faster, thus visually
showing the small primary chemical differences between thick and
thin layers.
Approximately 50 million years ago, volcanoes erupted in the
Kelowna area and along the Okanagan Valley. Since that time,
erosion by large streams removed much of the volcanic bedrock,
carving a broad deep valley along where Mission Creek now flows.
The Ice Age eroded and carved the land by several glaciers during
different times in the last one to two million years.
The last of these glaciers started to advance about 25,000 years
ago and filled the valley higher than any of the mountains of the
Okanagan today. It began to melt away about 15,000 years ago and
finally disappeared about 10,000 years ago.
As the Glacier melted in the Mission Creek Valley, the valley
was blocked or dammed for some time by large blocks of ice and
debris in Gallagher's Canyon. Material deposited from the ice
served to partly infill the ancient valley. But lots of ice
remained and the ice was still melting. This produced a lot of
water. The water could not escape because of the ice dam in the
canyon. Therefore, a large lake was formed along the upstream part
of Mission Creek Valley. The flat topped terraces along the present
valley sides were on the bottom of this ancient lake.
Water built up in the glacial lake behind the ice dam and
finally the dam burst about 10,000 years ago, and a catastrophic
flood occurred. All of this rushing and turbulent water was
responsible for cutting a steep-sided gorge along the face of Layer
Cake and eroding what we now call Gallagher's Canyon. One side (the
north side) of this gorge was the steep face of Layer Cake Hill.
The south side does not show this erosion effect because it was
still covered with a thick layer of ice and debris.
During this time when the lake was being drained at a very high
rate, high flows of melt water were also arriving here from the KLO
Creek valley. The combination of these water flows must have
created a huge whirlpool that swirled around carving out a portion
of Layer Cake Hill and finally forming a pinnacle of rock that we
call the "Pinnacle" today.
In order to log this earthcache you must do the
following: Email us with your estimate of the height of each of
the thin and thick layers and the height of the pinnacle
itself.
Failure to comply with these requirements WILL result in
log entry deletion.
Please take a picture, with your GPSr or your group in view of
the hill and post it with your log entry.