The notion that someday nature could swallow whole
something so colossal and concrete as a modern city
doesn't slide easily into our imaginations. The sheer titanic
presence of a New York City resists efforts to picture it
wasting away. The events of September 2001 showed only
what human beings with explosive hardware can do, not
crude processes like erosion or rot.... Nevertheless, the
time it would take nature to rid itself of what urbanity has
wrought may be less than we might suspect.
What point is the author most likely making with the example of September
11?