Physical Weathering | Game Quiz

Physical weathering represents one of Earth's most fundamental geological processes, where rocks and minerals break down into smaller pieces without changing their chemical composition. We will explore the mechanisms, factors, and impacts of this crucial geological phenomenon that shapes our planet's surface.

Temperature-Driven Physical Weathering

Temperature fluctuations drive several powerful weathering processes. In thermal expansion and contraction, different minerals within rocks expand and contract at varying rates as temperatures change. Over time, these differential movements create internal stresses that cause rocks to crack and fragment. This process proves particularly effective in desert environments, where daily temperature swings can exceed 40 degrees Celsius.

Freeze-Thaw Weathering Mechanisms

Frost weathering occurs when water enters cracks and crevices in rocks, then freezes. As water transforms into ice, it expands by approximately 9%, exerting tremendous pressure on the surrounding rock. This pressure, which can exceed 2,000 pounds per square inch, forces the cracks to widen. Repeated freeze-thaw cycles gradually break rocks apart through a process called frost wedging.

Salt Crystallization Effects

In coastal and arid regions, salt weathering plays a major role in breaking down rocks. As saltwater evaporates, crystals form within rock pores and cracks. These growing crystals exert pressure similar to ice formation. Additionally, when salts hydrate, they expand significantly, creating internal stresses that fragment rocks. Common salts involved include:

Sodium chloride (halite)
Calcium sulfate (gypsum)
Magnesium sulfate (epsomite)

Biological Physical Weathering

Living organisms contribute significantly to physical weathering through various mechanisms:

Root Action

Plant roots grow into rock cracks, gradually widening them through expansion pressure. Tree roots can generate pressures exceeding 15 atmospheres, sufficient to split large boulders.

Animal Activities

Burrowing animals displace and break down rock particles through their activities. Even small organisms like lichen create microscopic cracks in rock surfaces through their attachment processes.

Pressure Release Weathering

When deeply buried rocks move closer to Earth's surface through uplift or erosion, they experience pressure release or unloading. The reduction in confining pressure allows rocks to expand, creating sheet-like cracks parallel to the surface called exfoliation joints.