As a rule, caliche forms when minerals leach from the upper layer of soil and accumulate in the next layer. Usually consisting of carbonates in semiarid regions, less soluble minerals form caliche layers after all the carbonates have been leached from the soil in arid regions.
First, calcium combines with carbon dioxide dissolved in the soil’s water to form insoluble calcium carbonate which acts as a natural cement. Over time, soil particles become cemented together by calcium carbonate forming grains, then small clumps, then a distinct layer, and ultimately, a thicker, solid bed of deposits known as caliche. As it forms, the caliche layer gradually becomes deeper, and eventually moves into the underlying geological material which forms the next soil horizon.
Caliche occasionally forms in other ways: 1) water rising from capillary action in arid regions 2) plant roots taking up water through transpiration and leaving behind the dissolved calcium carbonate , or 3) trapped and evaporating water in porous rocks or fissures.
Caliche can range from white to light pink to reddish-brown in color, depending on the impurities present. In general, caliche deposition is a slow process, but if enough moisture is present in an otherwise arid site, it can accumulate fast enough to block a drain pipe.
Caliche is found worldwide: central and western Australia, India, Kalahari Desert, eastern Saudi Arabia, Andes Mountains, Sonora Desert, and western plains of USA. The uses of caliche vary with accessibility and percentage of calcium carbonate it contains. When purer forms of calcium carbonate are not available or financially feasible, it has been used in refining process for sugar. When fired, lime is produced which is used as a soil stabilizer, it has been used in production of Portland cement, and it its raw state can be used as mortar. It has been broadly used as base material for roads, and in rural areas of Southern Africa and Southwestern USA, where it is the cheapest and most readily accessible, it is very commonly used as road surface material. In the cache owners ancestral home area of the arid panhandles of Oklahoma & Texas, most of the rural roads are surfaced with a very white caliche taken from local "pits" that can be many feet deep/thick and extend laterally for miles!
Caliche beds can cause problems for agriculture. First, an impermeable caliche layer prevents water from draining properly, which can keep roots from getting enough oxygen. Salts can also build up in the soil due to the lack of drainage. Both of these situations are detrimental to plant growth. Second, the impermeable nature of caliche beds prevents plant roots from penetrating the bed, which limits the supply of nutrients, water, and space so they cannot develop normally. Third, caliche beds can also cause the surrounding soil to be base (as opposed to acidic). The base soil, along with calcium carbonate from the caliche, can prevent plants from getting enough nutrients, especially iron. An iron deficiency makes the young leaves turn yellow. Soil saturation above the caliche bed can make the condition worse.
Getting water to the early settlers of Delta area was big business in the 1880's and 1890's. Some organizations functioned as communes, most were stock companies, but a few were scams. One of those that was labeled, perhaps unjustly, as a scam was Peach Valley (site of the What! No Peaches GC series, and Guess what? No Peaches series southeast of Delta). Caliche played a major roll in the story of this valley which Muriel Marshall tells of in her book WHERE RIVERS MEET.
"Named [Peach Valley] by the company, the grayish, bleak expanse was extravagantly promoted nationwide in the 1890's as a paradise for growing fruit. Thousands of fruit trees were planted in ten- to forty-acre tracts. One double row of pear trees was a mile long. If you were an absentee owner (as most were, having bought by mail), the company would plant and tend your tract. The project failed, apparently not because of dishonest dealings but because, unknown to the company or anyone else, a layer of caliche shale under the topsoil prevented the plants from developing the deep roots they needed to survive. As it turned our, almost anything but fruit trees thrives in Peach Valley, given irrigation water and drainage ditches to keep alkali from forming like snow across the landscape."
At the coordinates, the highway offers fairly wide shoulders on either side. The caliche seen in the Cory Hill cut is very near the top in patchy little seams and is the lightest colored layer visible. You should be able to get all your information without leaving your vehicle. Note the multiple small striated layers of soil seen in the cross cut of the road embankment where the caliche is located. These are the remains of an alluvial fan deposited by nearby "Surface Creek" coming from the top of nearby Grand Mesa. Also note the many rocks lying about with a "chalky" coating on them, these were at one time "cemented" into the caliche layer and have tumbled down due to erosion. This chalky coating is the color you are looking for. The caliche layer is NOT the bands of light tan color in the central portions of the cut, this is sedimentary sandstone.
We would like to acknowledge the support of the rangers at the Grand Mesa National Forest Visitor Center, in particular the resident geologist, Mike Wiley, for having suggested this particular site and provided help, comments, and review in setting this Earthcache.
You may log your find immediately but to complete the process you must answer the following questions and e-mail them at the same time to TEAM kekj . Please do not post the answers in your log: It will be deleted!
Some of answers must be found at cache site, some found in cache description. More information on this common sedimentary rock can be found at your local library and online. One quick source which was used frequently in the description of this cache is http://en.wikipedia.org/wiki/Caliche .
- List 4 diverse regions in the world where caliche is found.
- List 2 beneficial uses of caliche and 2 challenges caliche present.
- What color is the caliche at cache site
- Approximately how far below the hill surface is the caliche deposit at the cache site
- Is there more than one layer of caliche at the cache site?
- Optional; We encourage you write in your web log what your personal experience (if any) has been with this sedimentary rock.
Congratulations to crawfordcollins on FTF!