Page 42 - (DK) Eyewitness - Mars

Volcanoes of Mars

Volcanoes are vents that release melted rock, or magma, from
underground. Magma rising through the mantle creates hot areas
on the crust. Magma that breaks through the crust becomes lava.
After flowing out of a volcano, lava cools and hardens, sometimes
spreading hundreds of miles. Martian volcanoes once spewed out
huge quantities of hot gas and water vapor, thickening the
atmosphere. Clouds of cooling water vapor may have turned to
OLYMPUS MONS CALDERA liquid water, creating seas, lakes, and rivers. Most Martian volcanoes
The caldera, or summit crater, of
Olympus Mons averages about 50 have been inactive for 40–100 million years, but some may have
miles (80 km) across, with walls as
deep as 1.75 miles (2.8 km). erupted within the past 10 million years—or even within half a
Calderas are produced when the million years. Volcanoes are found in three regions: the Tharsis
magma chamber collapses, usually
during eruptions. This overhead region, Elysium Planitia, and Hellas Planitia.
image is from the Mars Express
High Resolution Stereo Camera.
45 miles (72 km) wide

ABOVE EARTH’S GIANTS
Earth’s highest mountain, Mount
Everest in the Himalayas, and largest
volcano, Mauna Kea in Hawaii, 5.5 miles 6 miles
would be swallowed up in Olympus (9 km) high Olympus Mons, (10 km) high
Mons. This long-extinct volcano, the 16 miles (25 km) high
largest in the solar system, stands
three times higher than airliners Sea level
fly above Earth. Mount
Everest
Sea floor
Mauna Kea

SUNRISE OVER OLYMPUS
Majestic Olympus Mons, with a diameter of 400 miles
(640 km), is the highest region on Mars. Rising to 16 miles
(25 km), it is three times higher than any landform on Earth.
This artist’s perspective is from west to east, with a section
of the volcano’s great cliffs in shadow. Olympus Mons
covers an area approximately equal to the state of Kansas.