((In a collaborative effort like this, it might be best to leave some ambiguity for mythic past stuff, rather than setting it all in stone. Not totally chaotic, but ambiguous enough.))
For geography, though, it's best to err on this side of specificity. "To the West of the Chasm" is a bit ambiguous, since half of the planet is West of it. Do you mean there's a region of desert adjacent to the western rim, or is the entire Western rim a desert?
Center-west, near enough that the rim at the same latitude is mostly steppes/scrubland. It stretches perhaps a quarter of the way to the Farside, but rises into mountains. Just west of the mountains is a smaller sea, with verdant coastal jungles.
The Earth city exists through the mountains, literally. The major hub is on the seaward side, but a not-insignificant strip of development stretches through a series of tunnels and caverns, culminating in the minor hub on the desert side, which acts primarily as a port for airships and sandskimmers. The mountains themselves are rich in mineral resources. The remnants of an ancient structure project from the eastern edge of the mountains, a construct of stone and iron which extends several hundred meters past the city wall into the desert. Its original purpose is lost to time, but it serves as a convenient dock for airships.
Sandskimmers are desert vessels primarily used by the small oasis clans of the desert, and by the cities which border it; they resemble outrigger sailboats in terms of structure. The desert winds are useful at times, but hardly a constant; most skimmers tend to be family heirlooms, and their operators have a tendency towards bonding wind elementals.
The delicately balanced desert clans continue to exist primarily because they are the first (and often the best) scavengers to reach old ruins uncovered by the shifting sands. Nevertheless, such unpredictable fortunes and limited sources of water keep their numbers low.