CARBONATE-ROCK AQUIFERS— Continued
Some of the common types of karst features that develop on the land surface where limestone is exposed in the Mam- 39° ° ° moth Cave area of central Kentucky are shown in figure 28. 85 83 Recharge water enters the aquifer through sinkholes, swallow Spring Natural bridge holes, and sinking streams, some of which terminate at large Sinkholes 87° Karst valley depressions called blind valleys. These depressions, along with Sinking y stream
karst valleys and sinkholes, form when all or part of a cavern K E N T U C K Y Blind valley y roof collapses. Uncollapsed remnants of the cavern roof form 89° Mammoth Cave Area 37° yy natural bridges. Surface streams are scarce because most of yy yyySpring y the water is quickly routed underground through solution open- yyShale Blind valley yy y y ings. In the subsurface, most of the water moves through cav- yy yyy yy Swallow yy y y hole erns and other types of large solution openings. yy