Unlike other caves, the jewel cave carves by no underground rivers. The caves formed gradually through acid-rich groundwater and slow circulation of water. It has lots of stories associated with it and has a history of geology. In South Dakota’s hills, the oldest rock is metamorphic rocks and Precambrian-era igneous that got formed under pressure and heated nearly billion years ago.
During the period, between 345-360 million years ago, the area covers the shallow sea. The sea receded various times, and the carbonate and sediment shells accumulated sea over time and got compressed to create limestone known as Madison formation. The formation of the limestone shell backed ancient marine animals like the brachiopods. Also, Mississippian fossils in the cave can be seen even today.
Completed Description On Jewel Cave
As the formation of limestone takes place, gypsum or calcium sulfate bodies began to crystallize from water during evaporation. Irregular masses formed by the gypsum within the limestone.
Shortly, deposition of limestone can be seen, and gypsum beds form over the Pahasapa upper part that got dissolved as well as overlying collapse resulting in voids. The first cave stage marked at jewel cave development thus took place.
The receded and sea advancement across the area viewed several times. As the receding of the sea occurs, the limestone to open-air exposes. Also exposes to freshwater that began to dissolve limestone that creates caves and sinkholes. Cave development has the second phase at jewel cave.
Jewel Cave Formation
Finally around 310 million years ago, the deposition of Minne Lusa formation during the Pennsylvanian took place due to the carrying of freshwater from streams into the sea. The Minne Lusa contains sandstone primarily with beds of dolomite and limestone. It covers the Mississippian sinkholes, Pahasapa limestone, passages, and cave entrances. The reddish Paleofill was visible in the journey of jewel cave.
Approximately 40 million years ago, the black hill after receding of the sea began to form. The mountain range at the center of the Precambrian rocks thrust several feet. The sedimentary rocks containing Pahasapa and Minne Lusa erode areas, thus exposing Precambrian surface rocks. The residual sedimentary rocks surround the black hills from uplift away from the center.
In the black hills, the location of jewel cave surrounded by sedimentary rock is visible at 4 degrees approximately to the south-west.
Nearly 35 years ago, rainfall and climate change increased. Slowly underground freshwater start passing over the soil that is rich in CO2. It filled the cracks and rose in the limestone — the majority of jewel cave forms via this slow-moving water. The draining of water from the cave create springs.
Once the cave is filled with drained water, the formation of a cave known as speleothems began. Calcite speleothems made way through the CO2 soil, which is surface water, and it travels underground. This results in picking up of CaCO3 or calcite then dissolves the limestone. It enters cave passage, and carbon dioxide sends out acid and becomes water. In addition, the formation type depends on the dripping, seeping, or trickling water that comes out of cave passages.