Final answer:
Limestone is the type of bedrock most susceptible to forming sinkholes due to its dissolution when in contact with acidic groundwater. This high susceptibility is driven by limestone's composition and presence in areas with acidic water, which create underground cavities that can cause the surface to collapse.
Step-by-step explanation:
The type of bedrock most susceptible to forming sinkholes is basic rock formations that are easily dissolved by acidic groundwater, such as limestone. When acidic groundwater comes into contact with limestone, it often dissolves the limestone, creating cavities and voids that can eventually lead to the collapse of the overlying surface, forming a sinkhole. This process of dissolution and subsidence is influenced by factors such as the presence of water, the acidity of the water, the rock's porosity, and its permeability.
Groundwater moves through pores in rocks in the saturated zone, beneath the water table. High-porosity rocks can store large amounts of water and, if also highly permeable, allow it to flow easily. Sedimentary rocks like limestone are known for high porosity due to the way they form, from particles that once were loose material. Sinkholes are also influenced by activities such as groundwater withdrawal, which can affect the stability of the subsurface structures by lowering the water table.
Sandstones can also form aquifers due to their porosity, but limestone's susceptibility to acid makes it particularly prone to sinkhole formation. Understanding the geology and groundwater dynamics of an area is critical to assessing sinkhole risk, especially when planning developments or water well drilling.