Labels: text | screenshot OCR: By way of comparison, the Hawaiian volcanoes of Mauna Loa and Mauna Kea, the tallest MARS: GENERAL INFORMATION mountains on Earth, measure only about 9000 meters, of MARS'S SATELLITES D which 5000 meters is submerged beneath the waves of the Pacific Ocean ... Most Martian mountains are in fact volcanos; some are extremely ancient, almost 4 billion years old. Their bases can measure several hundred kilometers in diameter: Hadrica Patera, for example, a primitive volcano in the area of Hellas, is 600 kilometers in diameter. Olympus Mons is as large, but is more recent, dating back only about 200 million years. The most surprising feature of the Martian surface is without a doubt its many dry "riverbeds" and great canyons. Scientists are still not sure if water, or some other liquid, ever actually flowed through these valleys, but if it did several of them could have carried 1000 times more water than the Amazon. Kasei Vallis is one of the most stunning, being dotted with chains of narrow islands. As it flowed around one sharp right angle, the ancient river seems to have spilled over its banks, because the surrounding landscape is laced with ravines. The river-if there was one-may have had its source in a vast, chaotic region some 40 kilometers square, then flowed down a 1500-kilometer long depression, before reaching the plain not far from the Chryse site. All these features are thought to date back over three million years. MARS BETAT
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