Page 38 - (DK) Eyewitness - Mars

Canyons on Mars

The Solar System’s longest canyon network slashes 2,500
miles (4,023 km) from east to west across the surface of Mars.
This great system of cracks and rifts is Valles Marineris—400 miles
(644 km) at its widest, and four miles (7 km) down at its deepest.
These canyons were formed by volcanic stresses on the Tharsis
plateau region, where hot lava flowed, cooled, and then cracked. (A) Volcanic era
“Marsquakes” also opened the crust of the planet and deepened
rifts and valleys. Water might once have flowed through Martian
canyons, which now are swept by wind and dust. At the western
end of Valles Marineris is Noctis Labyrinthus, a complex pattern
of smaller fractures leading in every direction, like a maze—
another name for a labyrinth.

(B) Permafrost exposed
A SHUDDER AND ROAR FIRE, ICE, AND LANDSLIDES
Mars rumbles with the power of an These paintings show how, many
avalanche as canyon walls crumble millions of years ago, volcanic action
into landslides. This illustration built up the surface of the Tharsis
shows a towering cloud of dust rising region (A) and formed a bulge. Stress
as the wall of a Valles Marineris caused fractures—canyons—that
canyon suddenly gives way and broke the surface. These Marsquakes
collapses. Canyon floors are littered exposed layers of underground ice
with avalanche debris. (B) that held the rock and soil
together. Over time, the ice melted
or evaporated (C), leaving the canyon
walls unstable. Great landslides (D)
tore down the walls, creating wider (C) Evaporation and collapse
chasms—or “chasmas.” This cycle
of fracturing, evaporation, and
landslides—and possible water flow—
shaped Valles Marineris and
other Martian canyon systems.

(D) Canyons and chasms