How is mechanical weathering best described a. the buildup of chemical deposits on the surface b. the breakdown of rock through mechanical disintegration and physical stress c. the build up of rock formations overtime d. the breakdown of rock through decomposition of chemicals

Option (B)

Explanation:

The mechanical weathering refers to the break down of rocks into smaller particles or sediments by the physical processes. This takes place in the terrestrial areas. The temperature and rainfall plays an essential role in controlling the rate of mechanical weathering. They are also known as physical weathering.

The mechanical weathering process takes place in different ways-

(1) In the region where the temperature is relatively cold, the rocks that are comprised of fractures traps water in it during the day time and at night the water in these fractures gets frozen. As a result of this, the volume of water in the ice increases by about 9%, and it exerts a pressure on the sides of the rocks due to which the rock breaks. This process is known as the freeze and thaw method.

(2) In the places where there is maximum rainfall and temperature, the rocks get affected. The water and the wind flows over the rock surface, and due to the abrasion process, the rocks are eroded by water and wind respectively.

(3) In the regions where temperature changes occur frequently, the rocks undergo expansion in the day time due to high temperature and undergo contraction in the nighttime due to low temperature. Due to this continuous expansion and contraction process, the rocks are weathered.

Thus, the process of breaking down of rocks due to the physical processes is known as the mechanical weathering process.

Hence, the correct answer is option (B).

c. earths continental crust is thicker than its lithosphere.

because, the lithosphere is the outermost layer of the earth/ 100 km thick and is defined by its machanical properties.the lithosphere contains oceanic and continental crust that varies in age and thickness across locations and geologic time. the lithosphere is the coolest layer of the earth in terms of temperature. the term lithosphere should not be confused with the use of "geosphere" which is used to indicate all of earth systems, including the atmosphere, hydrosphere   and biosphere. the surface of the earth can be divided into the continental crust and the oceanic crust.   the continental crust is made mostly of granite while the oceanic crust is made of basalt. the average thickness of the continental crust is 25 miles and the average thickness of the oceanic crust is 5 miles.   three types of rock, igneous, sedimentary, and metamorphic, make up the surface of the earth. that's why 3 option is preferable.

he forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?