Willamette River Gravel Rocks! EarthCache
Willamette River Gravel Rocks!
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Gravel rocks for companies that mine or quarry it! This geocache is on the edge of a river where the gravel has built up for centuries! This rock used to be in the mountains but has washed down the Willamette River for ages!
To the west and east of this spot are two local gravel & sand companies that remove the aggregate on a daily basis! Look around in a full 360 degrees and you will note two gravel pits, gravel along the river and the gentle turn in the river. This popular boat area is often filled with people fishing, boats being loaded/unloaded, dogs splashing in the water, and geocachers! Before going to the spot, take a moment and look at the Google map option through Geocaching.com. Click on the “satellite” button and look closely at the mining operations, the sand/gravel bar, and the Willamette River!
Gravel is made up of small rocks of different sizes. It is often a collection of sand, clay, and small pieces of rock. It is a sedimentary rock and is often found in rivers, lakes, ocean beaches, and glaciers. You happen to be standing on a boat launch area of Willamette River that is know for its sand and gravel.
Gravel is collected by open-pit mining and quarrying. Both of the nearby companies use open-pit surface mining techniques.
(visit link) (picture)
What is GRAVEL & SAND?
Size Matters when speaking about rocks!
Gravel is a category of rock that has a range of sizes. To be in the gravel category, the rock pieces must be ‘loose’ and larger than 2 millimeters. Gravel is then divided into subcategories of cobble, pebbles, and granuals. Smaller than gravel is the category of sand.
GRAVEL:
Cobble: Geologically speaking, cobble is the largest size of the ‘gravel’ measures. Cobble ranges from 63 millimeters to 256 millimeters (a range of 2.5 inches to 10 inches!). The smaller size is that of a golf ball and the larger the size of volleyball! Cobbles are larger than pebbles but smaller than boulders.
Pebbles, on the other hand, are between 4-63 millimeters in size.
Granules: Granules are the smaller than pebbles but larger than sand. Granules are between 2-4 millimeters!
Even smaller is sand, which is greater than 0.062 millimeters to 2 millimeters in size. Sand particles are larger than silt particles but smaller than pebbles.
To learn more about the many levels of sand and muds, check out this page: (visit link)
In the PAST:
In the late 1800’s local gravel companies, such as Eugene Sand & Gravel just across the Willamette River from where you are standing, extracted grave (aggregates) from the river channel. When the river flooded, or ran high, it brought more gravel and rock material to the river channel, thus given the locals more to remove and sell.
NOW:
Many of Eugene’s concrete streets were paved with the sand and gravel from the local companies. Thousands of local residents and businesses use gravel and drive the need to mine/quarry.
YOUR TASK IN ORDER TO LOG THE CACHE
1) Find a sample of cobble, pebble and some sand and examine them closely. OPTIONAL: You have an option to take a photo and sharing it on the Geocaching site. As of 2011, photographs are no longer allowed to be a required part of an Earthcache. .
2) Look at the river height and estimate the distance between the first bridge support beam that (look for the one that is IN THE RIVER) of the bridge and the beach. The higher the river, the greater the distance will be.
3) Think of at least one way that you use gravel near your dwelling. Describe the use!
Sources of information:
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Additional Hints
(Decrypt)
Lbh pna ragre gur nern sebz rvgure fvqr bs gur oevqtr.