So here we have a simple map of North American land-form regions. The Laurentian Highlands are our bit of the shield. You see the flat lands of the Central Lowlands and Coastal Plain. You see the Appalachians and their foxtail, the 47. O________ P_______, straddling the joint-borders between Missouri, Arkansas and Oklahoma. Out west you see the northern Rockies and the Southern Rockies, which turn into the 48. C_________ P_______, the farther south you go. Then the mountain ranges on the Pacific coast, which are really two very different things. The mountains are volcanoes mostly in WA, OR, and northern California, but they are a non-volcanic block in southern California. The name Sierra Nevada includes both kinds of mountains. Now look at the different shades of tan on the map. One can see the gradual rise of the land across Oklahoma and the states to its north all the way to Minnesota. Elevations don't drop again until you hit west coast. Now look east toward Pennsylvania. It's another classic locale for 49. f____ b____ mountains, like the 50. Z______ we saw in Iran. You'll have noticed a little orphaned patch of green in eastern North Dakota. It's draining north into Canada, and it's probably the flattest place in the United States.