Fractures and joints in a rock increase surface area and allow weathering to occur more rapidly. In general, climates that have alternating periods of hot and cold weather allow the fastest rates of weathering. In warm, humid climates, chemical weathering is also fairly rapid.

If a large rock is broken into smaller pieces, weathering happens much more quickly. The rate of weathering increases because the surface area-to-volume ratio of the small rocks is greater than that of the large rock. So, a greater proportion of a smaller rock is exposed to weathering processes.

What are two factors that cause differential weathering? 2. the variation in the number of cracks and spacing of cracks in different parts of the rock.

Temperature and precipitation influence how fast parent materials weather and, thus, soil properties such as mineral composition and organic matter content. Temperature directly influences the speed of chemical reactions. The warmer the temperature, the faster reactions occur.

Temperature changes can also contribute to mechanical weathering in a process called thermal stress. Changes in temperature cause rock to expand (with heat) and contract (with cold). As this happens over and over again, the structure of the rock weakens.

Physical weathering is caused by the effects of changing temperature on rocks, causing the rock to break apart. The process is sometimes assisted by water. Freeze-thaw occurs when water continually seeps into cracks, freezes and expands, eventually breaking the rock apart.

Without weathering, geologic features would build up but would be less likely to break down. Weathering is the process that changes solid rock into sediments. Sediments were described in the Rocks chapter. With weathering, rock is disintegrated.