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The crust is pulling apart, which is why the valley is there.

• Albuquerque BasinThe basin is one of a chain along a continental rift: the crust here is pulling apart, which puts it in the same category of landform as East Africa rather than an ordinary river valley.
• Faults and basin fillThe basin has been filling with its own eroded material for millions of years, and the thickness of that fill is how the depth of the rift is known.
• ExtensionExtension means the crust is being stretched and thinned, and the faults are where it breaks as it goes.

Ranges that are the exposed side of a break.

• Sandia MountainsA tilted fault block with a granite core and a limestone cap, whose west face is essentially the exposed side of the break.
• Manzano RangeThe same structure continued south, less visited and more clearly readable for it.
• Ladron PeakAn isolated block of very old rock standing well out into the basin.

What came up through the rift.

• Jemez MountainsA volcanic field sitting on the rift's western margin, built and rebuilt over more than ten million years.
• Cerros del RioA basalt field north of the basin, cut through by the river into a gorge that exposes flow after flow.
• Albuquerque volcanoesA line of small cones on the west mesa, aligned along the fissure that fed them.

The sheet one eruption laid down, and what it became.

• Bandelier TuffThe ash sheet from the Valles eruptions blanketed the region, and almost everything soft in the landscape north of the basin is cut from it.
• Kasha-Katuwe Tent RocksCones of soft pumice-rich rock protected by harder caps, eroding into tapering forms.
• Pumice and caprockThe whole shape depends on one hard block sitting on soft rock, and it lasts exactly as long as the block does.

Hard rock, and the images cut into it.

• Petroglyph National MonumentTens of thousands of images pecked into the desert varnish on basalt along the escarpment west of the river.
• The West Mesa escarpmentThe escarpment is the eroded edge of the basalt flows, and it is why the boulders are where they are.
• Pueblo stewardshipThe images and the ground belong to living Pueblo communities, and the management of the monument is shared accordingly.

It has not stopped.

• Socorro magma bodyA large sheet of magma sits in the crust beneath Socorro, and the ground above it is measurably rising.
• SeismicityThe rift produces small earthquakes continuously, and the pattern of them maps the faults better than the surface does.
• GeodesyContinuous satellite positioning measures motion of a few millimetres a year, which is how the rate is actually known.

How the basin is actually measured.

• Mapping the basinA geological map is an interpretation drawn on a base, and the contacts between units are where the argument lives.
• Bureau and SurveyThe state bureau and the federal survey have mapped this ground repeatedly, and their published sheets are the primary record.
• Register of landformsEvery landform named on this site, with its coordinates.