Which technique is used to determine the depth of bedrock on a construction site?

The correct technique for determining the depth of bedrock on a construction site is through the use of a sounding rod. This method involves driving a rod into the ground until it reaches bedrock. The depth can then be measured directly, providing accurate information about how deep the bedrock lies beneath the surface. This technique is particularly effective for gaining insights into subsurface conditions in a straightforward, hands-on manner.

Soil boring, while also a method for subsurface investigation, involves drilling into the ground to extract soil samples for analysis, which may not be as immediate or direct for measuring bedrock depth. Ground penetrating radar is a remote sensing method useful for identifying different layers within the ground but may not provide definitive depth readings as accurately as a sounding rod. Seismic testing is used to measure the response of soil and rock layers to seismic waves; it can provide information about subsurface conditions, but it typically requires more complex analysis to interpret bedrock depth compared to the straightforward application of a sounding rod.