Valley
Part of speech: noun
Definition: An elongated depression between hills or mountains, often with a river flowing through it. The area which drains into a river. Any structure resembling one, e.g., the meeting point of two pitched roofs. The internal angle formed by the intersection of two sloping roof planes.
Example sentence: The reason why Silicon Valley is a worldwide innovation center is because it is a open culture that embraces diversity. You see people from all over the world. When you have many people from different backgrounds gathered together, that is where innovation comes from.
Canyon
Part of speech: noun
Definition: A valley, especially a long, narrow, steep valley, cut in rock by a river.
Example sentence: I can still remember my first experience of standing at the edge of the Grand Canyon and looking into it. It was so awesome, it took a fair amount of restraint to prevent me from jumping into it, because I was certain I could fly.