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In the late Miocene (about 10-7 million years ago) volcanoes deposited thick layers of ash across the Cappadocia region of central Turkey. The soft tuff alternates with more resistant layers of welded tuff, breccia, basaltic lava flows, and limestone. By the early Pliocene (5.4-4 million years ago) volcanism was localized to composite centers of basalt to rhyolite composition. In the mid-Pliocene (2.9 million years ago) extensive ash layers (ignimbrite) of the rhyodacitic Incesu/Valibaba Ignimbrite covered at least 300 square km and a large caldera (65 x 35 km) formed in eastern Cappadocia. All of these rocks accumulated in the Urgup basin. Erciyes Dag, a Holocene composite volcano, is located in the caldera. Stream erosion of the deposits has produced thousands of cones and towers up to 100 feet (30 m) in relief.
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North Africa/Middle East
