Mining Engineering Board Practice Exam – Practice Test & Prep Guide

Residual soil is specifically characterized by its formation process, which occurs in situ on the underlying bedrock. This means that residual soil is produced from the weathering and breakdown of the bedrock beneath it, rather than being transported to its current location by water, wind, or ice. This in situ development gives residual soil unique properties that are closely related to the parent material from which it originates.

Other soil types, such as alluvial or sedimentary soils, are typically formed from sediments that have been deposited by transportation mechanisms, rather than developing directly from the underlying geological material. The formation of residual soil is a gradual process that involves the chemical and physical weathering of rock, leading to a soil that retains characteristics of the bedrock.

In contrast, the notion that residual soil requires heavy rain for formation is not accurate, as the weathering process can occur in various climatic conditions. Additionally, while residual soil may contain sands or other particle sizes, it is not primarily defined by its sand content. Instead, the critical aspect is that it is formed where it sits, leading to its classification as residual soil.