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The word "Gelisol" comes from the Latin gelare meaning "to freeze", a reference to the process of cryoturbation that occurs from the alternating thawing and freezing characteristic of Gelisols. In the World Reference Base for Soil Resources [1] (WRB), most Gelisols belong to the Cryosols. In soil taxonomy, Gelisols key out before the Histosols ...
A good procedure is a chart, analogous to the familiar Snellen visual acuity chart, in which one letter in each row differs in depth (front or behind) sequentially increasing in difficulty. For children the fly test is ideal: the image of a fly is transilluminated by polarized light; wearing polarizing glasses the wing appears at a different ...
The TNO random dot stereotest (short: TNO stereo test or TNO test) is similar to the randot stereotest but is an anaglyph in place of a vectograph; that is, the patient wears red-green glasses (in place of the polarizing glasses used in the randot stereotest). Like other random dot stereotests, the TNO test offers no monocular clues. [4]
Vertisols: Usually mollic epipedon; high in shrinking and swelling clays; >30% clay to a depth of 50 cm; deep cracks (called gilgai) form when soil dries; form from parent material high in clay (e.g., shales, basins, exposed Bt horizons of old soils); 2.4% of global and 1.7% of U.S. ice-free land.
Entisols are common in the paleopedological record ever since the Silurian; however, unlike other soil orders (oxisol, ultisol, gelisol, etc) they do not have value as indicators of climate. Orthents may, in some cases, be indicative of an extremely ancient landscape with very little soil formation (i.e., Australia today).
A percolation test consists of digging one or more holes in the soil of the proposed leach field to a specified depth, presoaking the holes by maintaining a high water level in the holes, then running the test by filling the holes to a specific level and timing the drop of the water level as the water percolates into the surrounding soil.
The test method consists of pushing an instrumented cone, with the tip facing down, into the ground at a controlled rate (controlled between 1.5 -2.5 cm/s accepted). The resolution of the CPT in delineating stratigraphic layers is related to the size of the cone tip, with typical cone tips having a cross-sectional area of either 10 or 15 cm 2 ...
Stereoscopy creates the impression of three-dimensional depth from a pair of two-dimensional images. [5] Human vision, including the perception of depth, is a complex process, which only begins with the acquisition of visual information taken in through the eyes; much processing ensues within the brain, as it strives to make sense of the raw information.