Darwin's Beagle field notebooks (1831-1836)
I have certain proof that the S. part of continent of S. America has been elevated from 4 to 500 feet within the epoch of the existence of such shells as are now found on the coasts. It may possibly have been much more on the sea-coast & probably more in the Cordilleras. If the Andes were lowered till they formed (perhaps 3-4000 ft) a mere peninsula with outlying Islands, would not the climate probably be more like that of the S. Sea Islands, than its present parched nature. — At a remote Geological aera, I can show that this grand chain consisted of Volcanic Islands, covered with luxuriant forests, some of the trees out one of which, 15 feet in circumference, I have seen silicified & imbedded in marine strata. — If the mountains rose slowly, the change of climate would also deteriorate slowly; I know of no reason for denying that a large part of this may have taken place since S. America was peopled...
http://darwin-online.org.uk/
LOL. Now do you care to investigate what that epoch's time period might be? Some sea creatures have been around millions upon millions of years, much longer than our species -- especially modern humans. We go back only a million years or less. Also, there's a huge difference between the 400-500 foot elevation change in your example and the 12,500-foot elevation of Lake Titicaca! Localized elevation changes like Darwin describes can easily occur over "short" spans of a few million years. Mountain-building is a slow, incremental process that takes place on an enormously long time scale. This site gives a little insight into how it occurs: Orogeny