The hedgerows and trees are scarcely perceptible against the bare earth, whose slaty hue they have taken on.
灌木丛和树木在裸露的土地上几乎看不出来, 它们已经呈现出石板色。
英语百科
Slate gray
Slate gray is a gray color with a slight azure tinge that is a representation of the average color of the material slate. As a tertiary color, slate is an equal mix of purple and green pigments.
Slaty, referring to this color, is often used to describe birds.