Was an underground injection of molten lava responsible for the chaotic terrain in Hydraotes? Cinder cones point to an answer.

Sediments collected in this old impact basin record a history of Martian geological change going back billions of years.

Hunting traces of ancient life, NASA's next Mars rover may land in a ruined crater on the crumbling edge of the highlands.

Young rocky plains meet an ancient landscape where Daedalia's lava flows engulf the borders of Terra Sirenum.

A small basin within the 'Grand Canyon of Mars' may hold lakebed sediments that could preserve traces of early Martian life.

A valley in Arabia Terra slices through ancient clay-rich layers that may become a target for NASA's next Mars rover.

Waters that carved Ares and Tiu Valles poured out of the uplands and emptied into Chryse Planitia. They tell of an older, wetter Mars than today.

A huge landslide in Noctis Labyrinthus may have been caused when a meteorite impact blasted a crater near the canyon edge.

Petals of rocky debris encircle a fresh Martian crater, telling scientists secrets of blast waves and impacts.

While The Face is no artifact of an alien civilization, both it and the Cydonia region bear traces of climate changes that possibly favor life.

Rocky debris from Gratteri Crater lies scattered far across Mars. Some of the debris might even have reached Earth.

A landscape buried long ago is emerging again near the edge of the highlands in part of Mars' Arabia Terra

Molten rock knifed upward into a fault, widening it and releasing groundwater to erode a Martian valley

The gigantic mesa in Hebes Chasma is a record book of Mars' geologic past. Scientists have finally begun to open and read it.

Most Martian lavas are basalts, like those in Hawaii on Earth. But the lava picture for Nili Patera isn't so simple.

Deposits of sulfate materials in part of Valles Marineris point to much weathering by water

Landing a rover inside Mars' Valles Marineris might give scientists a good shot at finding traces of ancient life

Billions of years of deposition and erosion have scrawled a complex story on a large crater's smooth floor

Wind erosion, lava flows, and impacts have each helped shape the face of western Arabia Terra

Stacks of gypsum in Juventae Chasma recall an era when water was plentiful on Mars - and maybe life, too.

Water burst from the mesas of Iani Chaos long ago – can scientists find traces of ancient life here?

Terby Crater contains sediment layers going back at least 3 billion years in Martian history. It's a record book waiting to be opened.

Top of NASA's list of potential landing sites for the next Mars rover is a broad channel in Nili Fossae.

When Valles Marineris formed, it exposed a geological record book in the canyon walls

Layers of dust and sand emerge from the edge of the Martian north polar cap, as the ice cover retreats

Craters of widely different ages have made their mark on the streamlined islands of Maja Valles

NASA's next Mars rover may explore a water channel in a large crater. Or maybe a river delta nearby.

Ice and debris from countless climatic cycles have all but buried this Martian north polar crater.

A thick stack of sediments in an ancient crater hints at a long and complex geological history.

The 2009 Mars Science Laboratory may land in a crater that contains a thick stack of geological records.

The Martian feature known as White Rock is actually an eroding deposit of wind-blown sediments.

Impacts, floods, and tectonic forces have all left traces on this Martian outflow channel.

A deep canyon reveals ancient material under the northern polar cap of Mars.

The debris that fills Mamers Valles on Mars strongly suggests it flowed into place, carried by buried ice.

Water gushed from Cerberus Fossae, carving Athabasca Valles. The floods may have stopped only a few million years ago.

A new, highly detailed mosaic provides the best look ever into the largest canyon in the whole solar system.

Mudflows and lava carved channels in Granicus Valles west of Elysium Mons as volcanic heat melted ice in the ground.

The hematite found by Mars rover Opportunity in Meridiani Planum formed during a wet interval that probably was geologically brief.

A sea of sand dunes around Mars' north polar cap points to an ancient time when the polar region was ice-cap free.

Meteorites that strike ice-rich ground on Mars produce spectacular features suggesting such craters unfold in two stages.

The complex shapes of dunes in an ancient martian crater show that prevailing wind directions have shifted over the years as the climate changed.

A smooth, flat-bottomed valley lies where ancient floods carved a channel past lava-topped mesas billions of years ago.

Faulting, volcanic eruptions, and meteorite impacts unfold in a jumbled sequence across an ancient landscape in northern Tharsis.

Meteorites that strike ice-rich ground produce spectacular features suggesting that such craters unfold in two stages.

The floor of a large crater contains a field of sand dunes that may be blowing back into the pit where they originated.

The junction of several martian canyons reveals details in the layers of rock making up the region.

Isolated mesas on Mars stand surrounded by sheets of rocky rubble filled with ice, possible remnants of a former Ice Age.

Martian river beds? Flowing material indeed carved these channels, but most likely it was molten rock, not water.

A portion of the Valles Marineris canyon system contains several enormous overlapping landslides and provides a view into the misty depths of martian geologic time.

Acidalia Planitia is a large, flat region north of where the Mars Pathfinder spacecraft landed in July 1997. This nighttime infrared image of part of Acidalia little resembles a daytime view. But it can tell scientists about the physical properties of the martian surface, helping them map the proportion of rocks and dust.

Gusev Crater contains a complex set of features pointing to a long geological history. Mars rover Spirit is exploring the Columbia Hills in one part of Gusev.