"Swiss cheese limestone" (Pain Pond, San Salvador Island, Bahamas) 3 : 無料・フリー素材/写真
"Swiss cheese limestone" (Pain Pond, San Salvador Island, Bahamas) 3 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | "Swiss cheese limestone" along the rocky shore of Pain Pond, northeastern San Salvador Island, eastern Bahamas.Several categories of karst (dissolutional features in soluble rocks such as limestone) exist on islands in the Bahamas. Common small-scale karst features include phytokarst and solution tubes. Large-scale karst features include flank margin caves, pit caves, banana holes, lake drains, and blue holes.Bahamian islands are often said to be composed of swiss cheese, in reference to the significant degree of macroscale dissolutional porosity in the limestone bedrock. The holes seen in the aragonitic limestone shown above were produced by dissolution in a freshwater-salt water mixing zone. The water table below these holes is close to marine salinity. During storms and hurricanes, meteoric water having little to no salinity mixes with the salty water of the adjacent pond. Mixing zone waters have high aggressivity, in terms of calcium carbonate dissolution. This results in "swiss cheese limestone".Once developed, these large to small karst holes act as conduits for rainwater draining downward to the water table. Rainwater doesn't run off into rivers or streams on carbonate islands in the Bahamas. |
| 撮影日 | 2012-06-19 10:30:42 |
| 撮影者 | James St. John |
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