Hummocks and Hillocks EarthCache
This cache has been locked, but it is available for viewing.
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Difficulty:
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Terrain:
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Size: 
(other)
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The upper grasslands of Lac du Bois Provincial Park invite hikers
and geocachers to investigate the natural history of the area. The
area near the cache site is a treeless grassland, punctuated with
hillocks, hummocks, moraines, rills, kettles, kames, and drumlins.
You will enter the area and stand on a hillock to observe these
features. You are encouraged to go up and down adjacent hummocks
and hillocks to observe the landscape.
The area is mostly covered with igneous rock with some sedimentary
deposits. Bachelor Ridge on the east side is mostly 280 million
year old igneous rock. Most of Lac du Bois Park though, area is
composed of igneous rock formed between 30 million and 25 million
years ago. The surface features were formed about 25000 years ago
when ice sheets covered the valleys of the Interior of BC. The ice
depth ranged from 2000m in the deepest valleys to 500m thick on the
highest uplands.
The ice generally moved in a southeast direction, with ice moving
slowly or more quickly depending on the underlying slope, the
weight of the ice mass and the pressures of competing ice sheets.
The valley glaciers generally moved from the higher areas to the NW
towards the southeast, scraping, bulldozing, and reshaping the
land. Erosion features like drumlins were formed under the
ice.
As the glaciers retreated about 10 000 years ago, a surface layer
of glacial till was left behind, in some cases as deep as several
metres.
Glaciers deposited some loose rocks and fragments in a random
fashion which we call ablation till. Glaciofluvial deposits were
laid down in layers by meltwaters. They are characterized by being
sorted to size/type in a layer of strata.
As the glaciers retreated, they deposited moraines, boulders, and
till material into shapes.
- Terminal, lateral or ground moraines deposited by the
retreating glaciers leave ridges and hummocks.
- Kames were formed by meltwater flowing into depressions in the
ice and then are left as mounds or small hills. Kame Terraces are
found on hillsides.
- Alluvial fans are wide fan-shaped deposits at the base of hills
where the debris from an outwash has been deposited.
- Eskers are winding ridges of depositional debris following the
channel of a stream flowing beneath the ice.
- Erratics are boulders carried on top of the ice and deposited
in unlikely spots.
- Drumlins have a stream-lined teardrop shape with the steep side
facing the direction from which the ice came.
This cache was placed in an area composed of tracts of hillocks and
depressions of variable size and shape, formed by glacial deposits
formed around bedrock. Park in the established BC Parks parking
area (see the waypoint listed). Climb on top of a hillock to
observe the terrain. You are encouraged to go up and down adjacent
hillocks and ridges to observe the landscape.
To complete this geocache, cachers are asked to:
- Take a photograph with your GPS in the forefront, showing the
glacial features from the cache and post it to the cache
(optional)
- Scan the area looking for kames or kame terraces. Identify
their location (bearing) and distance from the cache
coordinates.
- Scan or search the area for erratics.
- Look for eskers or drumlins.
- Look at the ridge to the east-northeast and decide if it is
shaped like an esker or drumlin.
- Note the long ridge running north-south. Speculate on how it
was formed.
- Summarize your findings in an email to the owner, but do not
include your findings in the cache listing.
Additional Hints
(No hints available.)