How does Stephen E. Ambrose use imagery in Crazy Horse and Custer: The Parallel Lives of Two American Warriors?

Imagery:

“Whole forests of oak, beech, poplar, maple, and walnut, standing since Columbus, collapsed … from girdling and deadening with fire. There was in the heart of the new race no more consideration for the trees than for the game until the best of both were gone; steel conquered the West but chilled the soul of the conqueror. This assault on nature, than which few more frightful spectacles could be imagined, owed much to sheer need, but something also to a compelling desire to destroy conspicuous specimens of the fauna and flora of the wilderness. The origin of this mad destructiveness may be in doubt, but there is no question about its effect. The Ohio Valley today has neither trees nor animals to recall adequately the splendor of the garden of the Indian which the white man found and used so profligately.”