The Wump World is a childrens' picture book drawn and written by Bill Peet and published in 1970 by Houghton Mifflin.
The story opened upon a pleasant scene featuring affable looking, largish mammals with brown fur called Wumps, which look somewhat like a Capybara. (Bill owned one of these animals, the largest rodent in South America, featuring it in it's own book called Capyboppy.) These Wumps were content to laze the days away, resting under the shade of the Bumbershoot Trees, eating grass and drinking sweet water out of small ponds (these being the terrestrial sum of the flora and fauna of the world) until the alien invasion of the Pollutians from the Planet Pollutus!
"Zooming straight for the earth came a great flock of potbellied monsters, with tails and fins, spitting fire and shooting out streaks of black smoke." [1]
Debarking from their space ships, these Pollutians, small purplish-blue humanoids, declared the Wump World to be a wonderful, new clean place and set about right away to despoil it. From the bellies of their ships rolled down all manners of fantastic machines, each one belching black smoke from a stack. There were machines to tear out the Bumbershoot trees and grind them up in belly-grinders. There were bulldozers that scraped up the sod. Following these were machines to start erecting buildings and those for paving over the earth. Upon seeing these terrifying monsters, the Wumps fled their shady grove and took refuge down a hole where a series of caverns were.
Bill Peet spared no details in his depictions of all of the industrial age mechanical wonders that the Pollutians employ in developing their new world. To a young reader obsessed with trucks and construction equipment, it was a visual delight to see the scenes of the skyscrapers being erected and the factories belching purple and black smoke into the increasingly darkened skies and the tangle of freeways jam packed with speeding vehicles and ever growing piles of mechanical wreckage and refuse piling up and the pipes vomiting grey and green water into the lakes. But we felt sorry for the miserable looking Wumps in their underground caves, lapping from trickling spring water and eating mushrooms.
Soon, the Pollutians were hacking and sneezing and wheezing in the purplish polluted air that they created, grumbling amongst themselves before crying out to their leader that conditions had deteriorated beyond standing for. They demanded a new world! A cleaner better world! So the leader sent three of his best space cadets off to scout the cosmos.
After a few anxious pages, one of the scouts returned with news that he found a wonderful clean new world. All the pollutants embarked back into their pot-bellied spaceships and fired off into space leaving their befouled cities and the blackened skies of the Wump world behind.
The Wumps, who had been paved under the city, took notice of the sudden quiet. After some time, they decided to brave leaving the safety of their caverns. With a mighty push of its head, the largest Wump pushed through the concrete above to find a landscape absolutely alien and foreign. Leaving their caverns behind, the forlorn Wumps wandered around the abandoned, refuse strewn wasteland, upon the cold, hard concrete. They were about to give up and return to the caves when one Wump found one patch of green grass with a few bumbershoot trees and a small pool. "Wump, whumpity whump!" they cried, diving into the small patch of paradise.
In time, the post-script read, the Wump world would recover, but would never be the same again.
[1] http://www.billpeet.net/PAGES/wump.htm