In the end, rocks which started life as granite and related igneous rocks, also can become a soil consisting of coarse quartz-sand particles, finely divided silicate clays, and intermediate sized silt particles, plus soluble salts.
Some of the sand, silt, and clay and most of the dissolved materials are carried out to sea as part of the water cycle. That which remains as soil is virtually insoluble and resistant to further chemical decomposition, and small quantities of a great variety of other minerals are found in granite and related rocks. Some of these closely resemble those already described, but others are quite different. Among the others are apatite, a carrier of phosphorus; pyrite, a compound of iron and sulfer, purolusite, a source of manganeses; and tourmaline, the source of most of the boron in soils and in plants growing in them.
All of the soil-derived elements required by plants, animals, and human beings are found in mineral forms in granite and other igneous rocks. The larger part of the supplies of these mineral nutrients was dissolved out of the rock and it's residues during the soil-forming process and lost to sea. But enough remains attached to the fine clay particles to meet the needs of the plants that ultimately came into being and cover the soil. As these original plants grow up, mature, die, and fall back on the land, they return the borrowed mineral elements to the soils from which they had come. This returned portion is in a more readily usable state for new growths of plants than that that which was originally contained in clay.
In the end, rocks which started life as granite and related igneous rocks, also can become a soil consisting of coarse quartz-sand particles, finely divided silicate clays, and intermediate sized silt particles, plus soluble salts.
Some of the sand, silt, and clay and most of the dissolved materials are carried out to sea as part of the water cycle. That which remains as soil and can't be dissolved any further.
All of the soil-derived elements required by plants, animals, and human beings are found in mineral forms in granite and other igneous rocks. The larger part of the supplies of these mineral nutrients was dissolved out of the rock and it's residues during the soil-forming process and lost to sea. But enough remains attached to the fine clay particles to meet the needs of the plants that ultimately came into being and cover the soil. As these original plants grow up, mature, die, and fall back on the land, they return the borrowed mineral elements to the soils from which they had come. This returned portion is in a more readily usable state for new growths of plants than that that which was originally contained in clay.
In the end, rocks which started life as granite and related igneous rocks, also can become a soil consisting of coarse quartz-sand particles, finely divided silicate clays, and intermediate sized silt particles, plus soluble salts.
Some of the sand, silt, and clay and most of the dissolved materials are carried out to sea as part of the water cycle. That which remains as soil and can't be dissolved any further.
All of the soil-derived elements required by plants, animals, and human beings are found in mineral forms in granite and other igneous rocks. The larger part of the supplies of these mineral nutrients was dissolved out of the rock and it's residues during the soil-forming process and lost to sea. But enough remains attached to the fine clay particles to meet the needs of the plants that ultimately came into being and cover the soil. As these original plants grow up, mature, die, and fall back on the land, they return the borrowed mineral elements to the soils from which they had come. This returned portion is in a more readily usable state for new growths of plants than that that which was originally contained in clay.
