Existing comment:
Natural Bridge:
Natural Bridge is misnamed: this "bridge" is technically an arch. Natural bridges are carved by rushing streams, whereas subtler forms of weather have sculpted this opening.
The arch began as a recess in a narrow limestone fin. As moisture seeped into cracks, freezing and thawing combined with gravity and chemical weathering to erode the rock.
Hollows may have developed on both sides of the wall, gradually deepening until sky showed through.
Gaps usually form beneath harder caprock. Though the gully below did not carve the arch, runoff washes away debris and deepens the span.
It is impossible to predict when the span might fall. At Arches National Park similar spans have collapsed without warning, leaving pillars to erode more slowly.
Illusion of Permanence:
Natural Bridge appears solid, enduring. Though weather is constantly chipping away at the opening, the stone arch may last hundreds or thousands of years. In this case, appearance gives no clue to longevity. |