Cracks in Mount Rushmore
If anything looks like it could withstand time, its Mount Rushmore in the Black Hills of South Dakota. But up close, maintenance crews have found something disturbingcracks running through the granite faces of Washington, Jefferson, Theodore Roosevelt, and Lincoln. The monument isnt in immediate danger, but experts say that without a facelift the worlds largest sculpture could begin crumbling. Water runs into the cracks and freezes in winter, pushing on the rock with a force of 2,000 pounds per square inch.