Explain in detail the formation of soil due to various factors. What is the function of humus in soil?

(N/A) Soil formation factors:
$1$. Sun: The heat from the sun causes rocks to expand during the day and contract at night. This uneven expansion and contraction lead to the formation of cracks,eventually breaking the rocks into smaller pieces.
$2$. Water: Water enters the cracks in rocks. During winter,this water freezes and expands,exerting pressure that widens the cracks,eventually breaking the rocks. Additionally,fast-flowing water carries rock particles,causing them to collide and wear down into smaller particles.
$3$. Wind: Strong winds carry sand and rock particles,which rub against larger rocks,causing erosion and breaking them down over time.
$4$. Living Organisms: Lichens growing on rock surfaces release chemicals that powder the rock surface. Mosses and other plant roots grow into the cracks,further breaking the rocks into fine soil particles.
$(b)$ Function of Humus:
Humus makes the soil more porous,which allows water and air to penetrate deep into the ground,facilitating the growth of roots and supporting soil fertility.