Settling pieces and canyons

Scientists read landscapes like a book. Each place has clues about which process was at work. The Nile Delta in Egypt is a fan of rich mud and sand. The river slowed where it met the sea and dropped its sediment: that is deposition. The sand dunes of the Western Desert are piles of sand grains that the wind carried and then dropped. A rock with deep cracks and crumbs at its foot shows weathering. A scientific explanation has three parts. The claim answers the question in one sentence. The evidence is what we saw, measured or read. The reasoning joins the two: it tells why the evidence proves the claim. Good evidence is something other people can check, such as a measurement or a drawing.