Bedrock pinnacles, closed topographic depressions, solution cavities, caves,  and sinkholes are among the geologic features characteristic of karst terranes - i.e. areas underlain by soluble carbonate (limestone or dolomite) bedrock in wet climates.

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 In karst terranes, infiltrating precipitation dissolves the carbonate bedrock surface, causing the top of rock to retreat downward leaving behind a soil mantle of the insoluble clay and/or silica particles formerly bonded in the rock. Within the bedrock, water percolating along fractures, bedding planes, etc. dissolves the adjoining rock, creating solution channels.

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Solution channels can range in size from minor seams to scenic caves. At the irregular top of rock, spires or pinnacles of rock alternate with deep, usually clay-filled, seams or cutters. Within the soil mantle, there are often remnant, undissolved pieces of rock called float blocks.

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Sinkholes form where particularly enhanced infiltration into a sufficiently wide solution opening (often called a throat or chimney) washes the soil mantle down into cavities (either a single cave or a system of smaller solution channels) in the underlying rock - a process commonly called soil piping.  In areas where the residual soil mantle is clay-rich and cohesive, incipient sinkholes may not display any surficial topographic expression, and are present only as air-, water-, or mud-filled voids which may grow (or stope) upward.

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Eventually, the overlying soil arch may collapse under its own weight or under the weight of an overlying structure or passing vehicle.  The resulting sinkhole (often called a collapse sink) is commonly filled with the remains of the soil arch.  Note that sinkholes resulting from collapse of actual bedrock cave roofs are exceedingly rare.

In some cases, surficial subsidence may keep pace with soil piping at depth such that a sinkhole forms by progressive deepening of a surficial depression (sometimes called a subsidence sink) rather than by catastrophic collapse of a stoping void.

Note that the dissolution of bedrock occurs on a time scale measured in thousands to tens of thousands of years.  Therefore, the natural occurrence of new sinkholes is a rare occurrence on a human time scale. However, concentration of storm water and excess infiltration due to human activities such as construction, regrading, agriculture, storm water rerouting, etc. can trigger sinkholes virtually anywhere in a karst terrane - even on topographic highs or beneath paved streets or buildings. For instance, leaking sewer or water lines are a common cause of sinkhole damage to roadways.

Since sinkhole activity is allowed by bedrock cavities, and triggered/driven by infiltrating water, hydraulically active geologic features can act as foci for sinkhole activity.  In particular, where open faults, fractures, bedding planes or contacts act as preferred pathways for groundwater infiltration or flow, the water can dissolve networks of solution openings along the fault/fracture/bedding plane/contact. The enhanced infiltration also encourages movement of soil or soil fines into the solution openings, which may cause surficial subsidence and enhanced capture and infiltration of storm water, etc. in a positive feedback process.