• Tagged crater lakes, enivronment, geology, lakes, nature, volcano

If you approached the rim of a volcano and looked down into it, you might expect to see a lava pool, but if the volcano previously erupted and then the top of it collapsed into a huge bowl-shaped crater, or caldera, then what you might see when you peer over the rim is a beautiful crater lake. Sometimes the water is acidic and the lake has a bright greenish hue. Other times the water is a cloudy turquoise color, yet other times the lake may appear to be a very deep shade of blue. Crater Lake, Oregon, is one of the most well known, but crater lakes can be found all over the globe. If the volcano has been dormant for a long time, the water can be extremely clear because no river or streams flow into with sediment deposits. In some cases, water may have filled up an impact crater to form a lake, but this is less common. A few crater lakes were created by man via an atomic blast, but an artificially-created crater lake is the least common of all. All crater lakes were once a place where the earth experienced great violence, but now are a place of great beauty . . . even though the volcano can become active and violent again. Here are 44 photos of 42 of the world’s most beautiful crater lakes. [44 Photos]

• Tagged Earth's Bulls-Eye, Eye of Africa, geology, nature, pics, pictures, Richat Structure, Sahara, space

Since the beginning of space missions, the Earth’s bulls-eye caught the interest of astronauts in the otherwise featureless Sahara Desert. Over the years, it has become a landmark for astronauts. At first, the circular pattern was thought to have been a meteorite impact, but now the 31 mile wide bulls-eye, called the Richat Structure, is believed to be uplifted rock, a circular anticline, laid bare by erosion. Some people call this bulls-eye in the Sahara the “Eye of Africa.” [14 pics]