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Cannonball Wash and the Diablo Formation EarthCache

Hidden : 11/15/2006
Difficulty:
1 out of 5
Terrain:
3.5 out of 5

Size: Size:   not chosen (not chosen)

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Geocache Description:

Large and small, sometimes-round, sometimes very oddly-shaped concretions tumble down the steep hillsides above this wash.


In this wash, which is accessible by 4WD vehicles, off-road motorcycles, or ATVs, you will see an amazing collection of concretions which are sometimes spherical, but often oddly-shaped rocks comprised of mineral matter different from the surrounding substrate, which is sedimentary in nature.

Concretions are hard, compact accumulations of mineral matter that grow inside sedimentary rocks such as shale and sandstone.They are often comprised of a carbonate mineral such as calcite. However, they can be composed of other sedimentary minerals including ankerite, barite, dolomite, gypsum, pyrite, and siderite.

Concretions get their start when an appreciable amount of cementing material precipitates around an often-organic nucleus. This nucleus could be a piece of shell or fossil, or even a leaf or tooth. The process could be likened to how a pearl gets its start around a grain of sand in an oyster.

Ground water moves these hard masses into place.

In this location, the concretions range in size from very small to cannonball size and larger. In other locations, concretions can be huge and weigh several hundred pounds.

The hardness of the concretions varies and some show more erosion than others which is what leads to the creation of very odd shapes.

The etymology of the word "concretion" is from the Latin "con," which means "together," and "cresco," which means "to grow." Concretions often protrude from weathered cliffsides, as you will see at this location. In other areas, concretions are found along bedding planes or randomly distributed over mudhills. Sometimes they are found perched perilously on soft pedestals.

Access to the area is off S-22 near N 33° 16.017 W 116° 01.168. There are many twists and turns in the canyon and sometimes the correct route can be difficult to follow. Near N 33° 16.111 W 116° 02.446, bear left into the canyon.

I hope you enjoy your visit to this location. Do not disturb the concretions or take any samples.

To log this Earthcache, count the number of concretions in a 3' square area near where the coordinates lead you. Also, if possible, take a picture of one of the oddest-shaped concretions in the area with your GPSr in the picture.

Additional Hints (No hints available.)