For a scenic browse, and an answer-page for Guess The World...
It was Mari who first noticed the disturbing instability of the terrain beneath them. Curiously soft and flexible, it cushioned their footsteps, giving them the illusion that they were traversing an air-inflated rubber mattress...
But the illusion was tinged with horror, so alien was the experience and so far were they from the security of the known.
Mari's feet tingled as the soil heaved and pulsated with a startling life of its own. Frantically her grasp tightened on Bregge's arm.
"Jac, the ground is moving! Do you feel it? It is moving beneath us, Jac!"
Bregge stopped abruptly in his tracks. He sucked in his breath sharply. For an instant he remained unstably poised... His feet twisted about despite the frantic commands of his brain.
Beneath them the ground was unmistakably heaving. Surging up yeastily about them...
Frank Belknap Long, Jr., Red Moon (Thrilling Wonder Stories, June 1940)
…It was almost completely dark by the time they crossed the spaceport and started along the short road through the jungle to the town. The damp air was heavy with rank scent of the dense forest of fern-like trees. Queer “floating flowers” drifted against their faces, leaving lingering traces of exquisite perfume. Far off in the jungle a tree-cat wailed blood-chillingly, while overhead in the darkness was the leathery rattle of a passing dragon-hawk’s wings. Moon-bats called screechingly.
The stars blazed brightly down upon them. But over at the east horizon there was a ghostly uprush of green light from behind the horizon. It waxed stronger by the minute. Then the colossal green shield of Uranus pushed up into the sky, filling half the heavens as it poured down viridescent brilliance like an incredibly large emerald moon…
Edmond Hamilton, Treasure on Thunder Moon (1942)
>> Guess The World - Third Series
...The remainder of the entries Thad found less frequent, shorter, bearing the mark of excitement: landing upon Titania, the third and largest satellite of Uranus; unearthly forests, sheltering strange and monstrous life; the hunting of weird creatures, and mounting them for museum specimens.
Then the discovery of a ruined city, whose remains indicated that it had been built by a lost race of intelligent, spiderlike things; the finding of a temple whose walls were of precious metals, containing a crystal chest filled with wondrous gems; the smelting of the metal into convenient ingots, and the transfer of the treasure to the hold.
The first sinister note there entered the diary:
Some of the men say we shouldn’t have disturbed the temple. Think it will
bring us bad luck. Rubbish, of course. But one man did vanish while they
were
smelting the gold. Poor Mr. Tom
James. I suppose he ventured away
from
the rest, and something caught him…
Jack Williamson, Salvage in Space (Astounding Stories, March 1933)
>> Guess The World - Fourth Series