The uppermost soil horizon that contains a high amount of organic matter is known as the horizon.

answer; the tunica intima also called tunica interna, consists of elastic fibers,connective tissue and smooth muscle cells;

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs