The quotation is from Thomas Hardy's Return of the Native I think, or is connected to it. The place would be Salisbury Plain in the real world because that is what the heath in the novel is based on.
Is there a piece of music based on the novel? I don't know it if there is, but it would have had to been written no earlier than the end of the nineteenth century.
So probably a classical composer (New York Symphony Orchestra). "Swarthy monotony" suggest someone like John Adams rather than the lyrical minimalists but I'm guessing.