How does H. P. Lovecraft use imagery in Tales of the Cthulhu Mythos?

Examples of Imagery:

Then came out of the earth the black spirits of earth, mouldy and shadowy, and full of dim rumours picked up in caverns beneath forgotten sea-bottoms.

My friend was shrieking now; his screams blended with that gleeful, atrocious laughter from the empty air. His sagging body, dangling in space, bent backward once again as blood spurted from the torn neck, spraying like a ruby fountain.