system
Given the following post, respond as if you're commenting on Reddit:
human
How long does it take to create a marine arch, like Darwin's Arch, and how long do they last?

On May 18th we heard the sad news that Darwin's Arch, a 500-foot tall formation in the pacific had collapsed.  This event seemed reminiscent of the collapse of another great marine arch, The Arch of Kerguelen roughly 100 years ago. That remote island arch was apparently over 1000 feet tall and, like the Darwin Arch, is now just a set of majestic pillars.  Were we humans just lucky to have been able to witness these formations? How long do they take to form? (It must be more than 100 years suggesting that the majestic arch collapse rate is higher than the creation rate -- at least in the short term). How long can they last?
gpt
So, geologic structures take a longggg time to shape into their magnificent forms. For example, the Grand Canyon took an estimated 5-6 million years. The arches likely required lower levels of sediment movement to form. Therefore, it would form over hundreds of thousands or possibly millions of years; it would also be visible in its current arch-like form for hundreds to thousands of years presumably. So you are right that we are just lucky to observe these arches in that window. A thousand years is very short in the geologic timescale.