These low altitude regions are home to the numerous savage tribes of Green Martians. The dead sea bottoms compromise about 70% of the Northern hemisphere and 30% of the Southern Hemisphere of Barsoom.
“I found myself lying prone upon a bed of yellowish, moss like vegetation which stretched around me in all directions for interminable miles. I seemed to be lying in a deep, circular basin, along the outer verge of which I could distinguish the irregularities of low hills. It was midday, the sun was shinning full upon me and the heat of it was rather intense upon my naked body, yet no greater than would have been true under similar conditions on an Arizona desert. Here and there were slight outcroppings of quartz bearing rock which glistened in the sunlight . . . No water, and no other vegetation than the moss was in evidence.” (PM III)
“We traversed a trackless waste of moss which, bending to the pressure of broad tire or padded foot, rose up again behind us, leaving no sign that we had passed. We might indeed have been the wraiths of the departed dead upon the dead sea of that dying planet for all the sound or sign we made in passing. It was the first march of a large body of men and animals I had ever witnessed which raised no dust and left no spoor; for there is no dust upon Mars except in the cultivated districts during the winter months, and even then the absence of high winds renders it almost unnoticeable.” (PM XV)
“Neither Woola nor I had eaten since the previous day, but in so far as he was concerned it mattered but little, since practically all the animals of the dead sea bottoms of Mars are able to go for incredible periods without nourishment.” (WM II)