An earthquake on Dec. 16, 1811 caused parts of the Mississippi River to flow backwards.
243
It takes a drop of ocean water more than 1,000 years to circulate around the world.
61
A volcano has enough power to shoot ash as high as 50 km into the atmosphere.
59
If Manhattan had the same population density as Alaska, there would only be 15 people living there.
138
The 'King Ranch' in Texas is bigger than the state of Rhode Island.
49
Due to gravitational effects, you weigh slightly less when the moon is directly overhead.
55
Check your map! Virginia extends farther west than West Virginia.
67
The Amazon rainforest produces more than 20% the world's oxygen supply.
182