Iguassu Waterfalls

September 21, 2010

Iguassu falls
PhotographerMike Passow
Summary Author: Mike Passow; Jim Foster

September 2010 Earth Science Picture of the Day Viewer's ChoiceThe photo above shows a closeup view of the impressive Iguassu Falls on the border of Brazil and Argentina. These amazing falls occur where the Iguassu River, approximately two miles (3 km) wide at the point of the falls, plunge over basalt cliffs, some of which are 260 feet (80 m) high. The basalt cap rocks formed over 100 million years ago. Iguassu Falls is thought to be one of the widest falls in the world. Actually, hundreds of separate cataracts spread across the Iguassu River. Spotting a rainbow in the vicinity of a waterfall is easy work when the weather is sunny -- just make sure your back is to the Sun. Note also the faint secondary bow. Photo taken on August 11, 2010.

Photo Details: Camera: OLYMPUS IMAGING CORP, uT6000,ST6000; Focal Length: 5.0mm (35mm equivalent: 28mm); Aperture: f/5.0; Exposure Time: 0.0063 s (1/160); ISO equiv: 50.