Travel

BEGINNING OF THE SHENANDOAH VALLEY

The separation of the Americas from the continents of Europe and Africa, or the continental drift, occurred about 600 million years ago. A broad shallow depression from Alabama to Newfoundland was formed. Then, for 400 million years, an ancient sea flooded the area that is now the Appalachian Mountains. Layers of water-borne sediments accumulated on the ocean floor, followed by limestone sediments composed of fossilized marine animals and shells. The weight of the sediments eventually compressed the two layers into metamorphic rock.

As a result of the eons-old shifting of the earth's tectonic, or crystal, plates, North America and Africa collided. This elevated and fractured the sea floor, causing the older underlying layer of metamorphic rock to tilt upward and slide over the younger layer, creating a towering mountain range, the Appalachians.

GROWTH OF FORMATIONS

Most caves result from a simple formula. It consists of a layer of limestone, a mildly acidic mixture of water and carbon dioxide and time – precisely, millions of years. The formation of Luray Caverns began after the limestone of the Shenandoah Valley was formed as a result of the inland sea. The enclosing rocks consist of granular crystalline dolomite belonging to the lower part of the Beekmantown dolomite of Early Ordovician age. The entire cavern is confined to a zone only about 100 feet thick and occurred in coarse-grained crystalline dolomite.

The caverns contain no deposits that indicate the former presence of large flowing streams, and most of the cave deposits have been transported and deposited by very small discharges of water. Rain water picks up diluted carbonic acid when it seeps through decaying vegetation in the soil above the rock. The hollowing-out of a limestone cave begins as this acidified water percolated through the fissured limestone dissolving and eroding layers along the way. Water eventually fills all openings enlarging the existing crevices. Run-off soon descends into lower levels of the earth leaving huge limestone chambers.

As the large volumes of water subside and only slow seepage continues, nature's decorating process begins. Upon entering the unique cave atmosphere, the solution of calcium carbonate gives up some of its carbon dioxide and allows a precipitation of lime to form. This precipitation begins as a thin deposit ring of crystallized calcite. As this process is continued, stalactites form from the ceiling. As the drops fall to the floor, deposits build forming stalagmites. When a stalactite growing down from the ceiling meets a stalagmite growing from the floor, a column or pillar is formed.

Luray Caverns is an active cave where new deposits accumulate at the rate of one cubic inch in 120 years.

DRIPSTONE

Stalactites are formed often in a fluted and uniformed fashion from the ceiling down. Stalagmites build with distinct mounds and ridges on their way toward the ceiling.

Dripstone, in addition to covering the ceilings and floors, is also abundant on cavern walls. An often more massive decoration is formed when the mineral bearing water spreads over the limestone walls or builds its deposits from a protruding ledge. These crystalline deposits, or flowstone, form draperies and frozen waterfalls, veils and tents. Titania's Veil is and example of this type of cave decoration.