Apparently, Great Britain became an island due to a big flood (not gradual erosion). Don't let the Old Earth Creationists hear about this...
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Parents, don't let your kids drink soft drinks (except root beer):
Root beer may be 'safest' soft drink for teeth
"No Till" is a confusing term. For most people who know nothing about agriculture, the word "till" isn't particularly revealing - it sounds like there's no cash register. Given that level of knowledge, when you are reassured that no tillage means less erosion, you aren't going to crticize.
From New Scientist, here is a short article discussing five cases of small populations forced to relocate or plan to relocate due to sea level rise, caused by climate change.
To answer that question briefly, it is really really old if you mean "how old are the oldest rocks that are exposed by the Grand Canyon," and it is probably just a few million years old (5 or 6 by some estimates) if you mean "how long did the canyon itself take to form."