The description of the valley of ashes opens this chapter. Literally, what is the valley of ashes?

The Valley of Ashes is a barren, wasteland, tucked in between the opulent Eggs and New York City. It is a forgetten place.... a place of poverty.

literally, valley of ashes means the destruction of human civilization and humanity.The whole thing in the valley of ashes is covered with ashes which means the whole world is covered with destruction.The valley of ashes cause the tragic ending of the novel.It destroys the civilization, morality and manner.