what is dirt, and how does it come to be?

Soil is not the same as dirt. Dirt is a general term for particles of matter suspended in the air. It’s in no way scientific. Soil on the other hand is the result of exposed bedrock. Water, wind, and acids from tree leaves start to break down exposed bedrock and forms soil. The formation of soil goes down into the bedrock as more of the parent rock is broken down. Thus you can several distinct layers where the conditions of soil formation are different.

Soil types vary because the conditions during its formation vary. In rainforests, the soils are red because the iron in the soil oxidizes due to high drainage and moisture. Swamps have black soils because the organic matter decomposes underwater, so different bacteria cause anaerobic decomposition.

One of the biggest drivers of soil formation is the chemical composition of the ground water, as most of soil formation is driven by chemical, not mechanical, weathering, but the start of the process requires manual breaking of the parent rock to for cavities for chemical waters to flow into.

Edit: dust is a general term for particles in air. Dirt is more of a general term used fitting what soil is but is not accepted as a scientific term

Edit 2: Woah thanks for gold! All my classes in soil science have finally served me well.

Eroded rock, volcanic ash, and decaying plant matter are the main constituents though proportions will vary with location.

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