Final answer:
The statement that brush fires and forest fires speed the process of mechanical weathering is false. Fires are related to ecological processes and succession rather than the physical breakdown of rocks characteristic of mechanical weathering.
Step-by-step explanation:
The statement Brush fires and forest fires speed the process of mechanical weathering is false. Mechanical weathering refers to the physical breakdown of rocks without changing their chemical composition, typically through processes like freezing and thawing, abrasion, or exfoliation. Brush fires and forest fires do not contribute to mechanical weathering; instead, they are involved in ecological processes. Forest fires can lead to the removal of vegetation, affecting soil stability and potentially leading to increased erosion. Moreover, fires can change the landscape and promote ecological succession where new plants sprout among the charred remains, sometimes favoring species adapted to fire.
While fires contribute nutrients like nitrogen to the soil and can influence the moisture of microclimates, mechanical weathering is not accelerated by fires. Instead, fires can contribute to chemical changes in the soil due to ash deposition, but these do not represent mechanical weathering processes. Brush and forest fires are more associated with ecological disturbance and the potential transformation of ecosystems, as seen in the grass-fire cycle.
Thus, fires do not speed up the mechanical breakdown of rocks, which is the central characteristic of mechanical weathering.