1/14/2024 0 Comments Ephemeral pond diagram![]() ![]() There are other examples, however, that remain filled with water and do not dry up. Some dolines here in the hills contain shallow ephemeral ponds and wetlands that hold rainwater for extended periods until it seeps downwards.As has been suggested in the descriptions above, there is a complete continuum between dolines and sinkholes and in some areas, these terms are used interchangeably. Various dolines are illustrated in the adjacent diagram with the middle feature transitioning into a sinkhole.With time, a doline may develop into a sinkhole, especially where there is a corresponding solution cavity of sufficient size directly below the feature.A doline is a shallow funnel or dish-shaped depression due to the slow dissolution of bedrock where there are intersecting networks of fissures and fractures.In the instance shown below, all of the cavern growth takes place in the vadose zone above the water table, which is less common here in the Black Hills than in some other areas. The following panel of diagrams show the development cycle of a typical sinkhole from incipient dissolution, through cavern enlargement and then through eventual collapse.Although numerous Black Hills caves have sinkhole entrances, many more are accessed through enlarged solution cavities and fractures exposed in drainages, bluffs and cliffs.The adjacent diagram shows what a fully developed sinkhole collapse looks like. Sinkholes are steep sided, roughly circular collapse features which often lead directly or indirectly into an underground cavity.Nonetheless, they are a locally prominent feature in some of our better explored areas of Karst development. Sinkholes and dolines are both quite common in most karstic terrains, but are not quite as widespread in the Black Hills as in other major karst areas. ![]()
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