V-shaped, formed by a river and U-shaped after carving by a glacier. Plus variations thereof.

I believe you get canyons when the land is going up and the river is cutting down. A nice frame shift I saw in a nature program was to not think of the river as moving, but instead think of the river as stationary and the land (the continental plates) as moving around it. You’ll get a canyon when the land is pushing up and the river is cutting down. Much like pushing a block of cheese up through a cheese wire. OK the cheese is my analogy which is why it’s not as good.

Had a helpful comment from Austin correcting and explaining, “canyons are formed any time the weathering action of some force (i.e. a flowing river) greatly outpaces the surrounding environment’s eroding forces. For example, the grand canyon is so deep because it never rains in the desert, and wind doesn’t erode as quickly as water.”

Shapes of Valleys

Practise thinking in space and time. An alternative to Powers of 10 that encourages you to look at a situation in space and time. Helpful for getting a new perspective. The easiest way I know is to literally draw the boxes. Start with what you’re dealing with in the centre then start filling the rest out. Another tool from the TRIZ toolkit.

9 Windows

Why fit in when you were born to stand out. (Dr Seuss)

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The folk economics of ins and outs