Geologists believe the island is a "plug" left behind from an extinct volcano.

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Saridal was established 45 years ago by semi-nomadic tribesmen on the edge of Karacadag, an extinct volcano east of Diyarbakir.

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That's where Denbury owns the Jackson Dome, an extinct volcano that contains the biggest source of naturally occurring carbon dioxide on the Gulf Coast.

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It was finally concluded that the lake's lower levels had become saturated by carbon dioxide gas (CO2) due to gaseous springs which bubbled up from the extinct volcano beneath.

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