Jasper seam at Hannah Point, Livingston Island EarthCache
Jasper seam at Hannah Point, Livingston Island
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Attention: Be aware of sea elephants at the location.
Do not step on the jasper seams.
It is not allowed to collect samples or minerals, please take just photos.
Livingston Island
Livingston is a quite young volcanic island in the South Shetland Islands, Antarctica. Main parts of the island consist of basalt and basaltic lava. Some (rare) areas are covert with secondary sediments. The island is covered with glaciers. The glaciers transport fossil-containing sediment rocks to the beach sporadically.
Hannah Point
Hannah Point is located on the south coast of Livingston Island. It is named after the British vessel Hannah that wrecked here in 1820. The rocks at Hannah point consist of basalt and basaltic lava. See the picture that shows a basalt-tower nearby. The upper part of the small island is formed of basalt columns. Basalt columns are formed by the cooling of a thick lava flow.
Small island with columns and pillows
Temperature gradients between the air/surface and the hot bottom of the basalt stream caused contraction forces.
The basalt under the column-formation was erupted not into air but under water. Contact with the water quenches the surface and the lava forms a distinctive pillow shape.
At the coordinates a big (~10 cm) crack crosses the basaltic rock. This crack was produced about 10 mio. years ago during a big vulcanic explosion not far away.
This crack is filled with a red, glass-like material: Jasper.
The crack was flooded with mineral-rich water. Under very high pressure and at temperatures of about 250-300°C (supercritical) water is a quite good solvent for quartz. During the cooling of the rock quartz cristalizes from the hot solution and over the time it fills the crack completely.
Basalt is a quite iron-rich material and iron ions (Fe3+) are very mobile in contact with hot water solutions. They intruded the quartz filling or the hydrothermal solution and causes the red color.
Main jasper seam
Just a small gemstone
Jasper is a usually red form of chalcedony, a quartz variety. Jasper is used as a gemstone and for ornamentation.
Puzzel stone
To log this cache, please answer the following questions per e-mail. Feel free to log directly, we will contact you if we see any problems. Photos at the location (with or without you) are welcome.
- 1) Estimate the strike-and-fall of the main seam.
- 2) There is a significant branch-seam, estimate the angle with the main seam.
- 3) Near the beach you find a special-shaped stone (the puzzel stone). What is the name of such a stone?
- 4) Can you imagine the origin of this stone (it is not from Livingston)?
- 5) Add a foto from nearby that proofes your visit. Please do not spoil geological features!
Greetings and happy logging, Rheinflut1995
Additional Hints
(No hints available.)