Aldergrove Park Glacial Erratic EarthCache
Size:  (not chosen)
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I used to frequent this park a lot as a child and teen growing up in this area. My friends and I used to climb the rock and hang out when we were bored. We didn't do any of the graffiti though. There are trails that lead right up to the rock.
A glacial erratic is a piece of rock carried by glacial ice some distance from the rock outcrop from which it came.
Geologists identify erratics by studying the composition of rocks surrounding the position of the erratic and the composition of the erratic itself. Scientists have determined that erratics pointed to an ice age in Earth's past.
Geologists have suggested that landslides or rockfalls initially dropped the rocks on top of glacial ice. The glaciers continued to move, carrying the rocks with it. When the ice melted, the erratics were left in their present locations.
Erratics can range in size from pebbles to large boulders. The largest known Glacial erratic is the "Big Rock" erratic(16,500 tons) near Okotoks, Alberta, Canada. Other examples of glacial erratics include:
A fern-covered erratic the size of a garage is found on Cougar Mountain near Seattle. White Rock, British Columbia derives its name from a sea-side erratic the size of a garage found on the beach at Semiahmoo Bay, right at the US border with Washington State. The Foothills Erratics Train is a deposit of rocks of many sizes. These deposits stretch in a narrow belt for about 600 km from the Athabasca River Valley in Alberta to southwestern Alberta.
During the most recent North American glaciation, the Wisconsin glaciation (70,000 to 10,000 years ago), ice sheets extended to about 45 degrees north latitude. This Wisconsinian glaciation left widespread impacts on the North American landscape.
Ice Age sediments deposited during the Pleistocene Epoch (2 million to 11,000 years ago) underlie gently rolling uplands (15 to 250 m elevation) of the Fraser Valley. Most Ice Age sediments in the Vancouver area date to the last glaciation, about 25,000 to 11,000 years ago, and in particular to the period of glacier retreat when areas below 200 m elevation were covered by the sea.
In Eastern Canada and U.S., the Great Lakes and the Finger Lakes were carved by ice deepening old valleys. Most of the lakes in Minnesota and Wisconsin were gouged out by glaciers and later filled with glacial meltwaters. The old Teays River drainage system was radically altered and largely reshaped into the Ohio River drainage ystem.
Other rivers were dammed and diverted to new channels, such as the Niagara, which formed a dramatic waterfall and gorge, when the waterflow encountered a limestone escarpment.
In between ice ages, there are multi-million year periods of more temperate, almost tropical, climate, but also within the ice ages (or at least within the last one), temperate and severe periods occur. The colder periods are known as glacial periods, the warmer periods as interglacials. The Earth is in an interglacial period now, the last retreat ending about 10,000 years ago.
"As a huge Stone is sometimes seen to lie
Couched on the bald top of an eminence;
Wonder to all who do the same espy,
By what means it could thither come, and whence;
So that it seems a thing endued with sense:
Like a Sea-beast crawled forth, that on a shelf
Of rock or sand reposeth, there to sun itself."
W Wordsworth 1807 The Leech Gatherer
To log this cache, you must e-mail me some information regarding the site that you learned while there. This could be done by answering one or more of the following questions:
1) What is the rock's height, diameter, length, radius, circumference, etc. (Choose one or more)
2) You could also try and calculate the approximate mass of the rock. The density of granite is approximately 2600 kg per cubic metre. Using your size measurements (length x width x height) you can calculate the mass if you know the density. (I don't think this rock is actually made from granite I just chose granite because I don't know what the rock is made of so you can use granite or a different type of rock as long as you tell me what kind of rock you are using for your density calculations).
3) If you do know what type of rock this is, you could also use that as your answer.
To confirm that you visited the site you must also show a photo of you and or your GPSr with the rock. Any logs that do not meet the requirements will be deleted because Earthcaches are now meant to be educational.
Thank you for visiting my Earthcache.