When did waterfalls first appear?

What is a Carolinian Forest? Who lives in the taiga forest in russia? How long does it take to go through the Air and space museum? Does the Panama Rainforest have indigenous tribes? What are the major differences of renaissance castles and medieval castles? What adaptations do the minks have in the wetlands? The world's tallest building opened Monday January 4 2010 in which Middle Eastern country? Does flame of the forest reproduce by seed? What type of crabs live in rock pools? What is the climate of Mt Rushmore? What is the cardiff castle made out of? Did the national road ran from the great lakes to the Gulf of Mexico and linked the nation along its north-south axis? What is the color of the ocean on a cloudy day? What force keeps a bridge from breaking? How long did the forbidden city take to complete? What Mediterranean country is landlocked? How does red sea affect people lives? Why is the Eiffel tower painted every 7 years? The end of a river? What city has the most buildings over 50 stories?