How would you be able to find a: -Glacial Troughs -Ribbon Lakes on a Map?

-Glacial Troughs, remember, are Flat Valleys with really Steep Sides. -There is Virtually no Contour Lines in the Valley, another Hint to Find it -Also, a River that Runs down the Valley that looks Really Small is yet again Another Hint that its a Glacial Trough -For a Ribbon Lake, then when you have Identified a Glacial Trough, then finding a Lake is quite Easy; its Blue