I call it "Wadi", after the term for a dry gorge/river bed.
It's not very out-there, more of a typical desert with typical desert life. There are jerboa (kangaroo rat), horned viper, sand cat, lizard, and a species of desert tapir unique to the Age. Cacti, cypress, acacia, needle-grass, and reeds grow in the shade of the gorge's lip. It is a lush oasis in a vast, rough, mountain-rimmed desert.
The valley was carved out by a sluggish, brutal river long ago. Over time, the river weathered away the softer rocks, leaving the harder rocks to form the lip and the walls. In time, at the head of the valley, the river met a layer of tough rock, and a waterfall was born. The spray of the falls eventually knocked out a deep plunge pool, and a rock shelter behind it in the cliff face (this is the link-in point.) The waters settled down, as climate change began to shrivel up the montane glaciers that fed them. But they continued, even if slowly, and soon an opening into a subterranean river was breached by the erosion on the plunge pool floor; the river flowed down in a great hurry, filling the cavern.
To top it off, a sudden rockslide from the foot of a nearby mountain blocked the mouth of the valley, and the river was forced back. In time, with its once-exit blocked and a new exit open, the river course changed, and the valley dried up. But not before laying down layers of nutrient-rich sediment. This led to the growth of plentiful vegetation in the wake of the river, and this called out to the desert inhabitants like the tapir, jerboa, and sand cat.
I'd like to note that the desert tapir is a small, pygmy-like animal. It has short, bristled sandy fur, and large ears to help keep it cool. It feeds on the leaves of adult cypress and acacia, and their shoots too. When in times of drought, they will secure water by lacerating cactus with an opposable "claw" they posses on their front paws. They're relatively gentle, yet skittish creatures. They fall prey to the sand cat.
I will post some sketches and drawings very soon.
