I now know where the style of writing in the African spam letters comes from. Yikes! Talk about ponderous reading.
Chapter I "The Genesis of a World" -Jupiter, Saturn, Uranus and Neptune are baby planets. Just look at how bouncy and gassy they are! Mercury and Venus are aged planets. Earth and Mars are just right except Mars has aged more because it is little. Mars is flat with no mountains because it is little.
Chapter II "The Evolution of Life" - If there is water, life will evolve. Dry land makes intelligence evolve. Whales don't count.
Chapter III "The Sun Dominant" - The Sun supplies heat after the Earth cools and the clouds go away. We get seasons and smart land animals.
Chapter IV "Mars and the Future of Earth" - All of our water is evaporating into space! We're all going to die!
Chapter V "The Canals and Oases of Mars" - Canals, I seen 'em! They must be there, they must be! We got pictures! They're just not back from the drug store yet!
Chapter VI "Proof of Life on Mars" - When dry land happens, brains appears, and besides there are Canals I tell you!
In fairness to Percy, Plate Tectonics had not been invented yet, the film was all black and white and largely orthochromatic (not sensitive to red), and he wanted to see those Canals so hard. When he wrote the book he was a half century from space travel and plate tectonics. And he did blow up a couple of theories that were far worse than his own. (i.e. a giant early sun heating up both poles of the Earth.)
I'm glad I read it, but oh boy! what a slog!