Mollisols primarily occur in the middle latitudes and are extensive in prairie regions such as the Great Plains of the US. Globally, they occupy ~7.0% of the ice-free land area. In the US, they are the most extensive soil order, accounting for ~21.5% of the land area. Mollisols are among some of the most important and productive agricultural soils in the world and are extensively used for this purpose. Mollisols are divided into 8 suborders: Albolls, Aquolls, Rendolls, Gelolls, Cryolls, Xerolls, Ustolls, and Udolls. Click here for more information about these suborders.
Simple Answer: James Watson and Francis Crick are credited with the first correct double-helix model of DNA structure published in 1953 in the journal Nature.
Taken in 1952, this image is the first X-ray picture of DNA, which led to the discovery of its molecular structure by Watson and Crick. Created by Rosalind Franklin using a technique called X-ray crystallography, it revealed the helical shape of the DNA molecule.