Mineral King Karst Topography EarthCache

Karst features are common in the marble formations found in the Sierra Nevada Mountains.

Overnight trips to into this wilderness require a permit from the Mineral King ranger station. Reservations are recommended. The area is close to 10,000 feet high, so be prepared.

Within the Sierra Nevada Batholith are a number of roof pendants (Sequoia Roof Pendant and The Dinkey Creek Roof Pendant for example). Within these roof pendants are layers of marble. One the units a Jurassic and/or Triassic coarse grained marble.

Marble is a carbonate rock, metamorphosized limestone. This type of rock dissolves in acid. Rain water is a weak acid. As rain falls through the air, it reacts with carbon dioxide along with sulfur oxides, nitrogen, and other natural compounds to form weak acids.

As these acids percolated through the marble, the water slowly dissolves the stone. Weak points along bedding planes (the contact between layers within a sedimentary rock) or fractures dissolve fastest forming cracks. Once the ground water dissolves the cracks to a critical width, the flow of water becomes turbulent increasing the rate that the limestone is dissolved. Even more water is then channeled though these widened cracks potentially creating a cavern like Crystal Cave. If a cavern does form the weight of the overlying soil could eventually break the roof of the cavern. The surface material falls down filling the cavern creating a sinkhole at the surface. That is likely what happened to create the bowl shaped depression at this location.

A stream still flows into the sink hole, but is not filling it up. Thus the water must continue to be flowing through the boulders at the surface and into a subterranean channel. The stream disappears from view, giving the landform the name disappearing or sinking stream. Theoretically, the water must come out of the ground somewhere, or else the cavern would fill up creating a pond here.

Karst topography is an area where the features noted above, and a few others, are relatively common.

Logging requirements:

1. The text "GC4QPN8 Mineral King Karst Topography" on the first line.
2. The number of people in your group (put in the log as well).
3. Examine the marble and guess at to if the acids followed bedding planes or a fracture?
4. At the next coordinates (36.43366667, -118.59733333) what features of karst topography do you see?

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