The Navajo are the second largest tribe in the U.S. and they have the largest reservation stretching across Colorado, Utah, New Mexico and Arizona with over 25,000 square miles. They were also among the largest group of Indians to migrate to Los Angeles in the 1950s and 60s.
The ionosphere is a shell of electrons and electrically charged atoms and molecules that surrounds the Earth, stretching from a height of about 50 km (31 mi) to more than 1,000 km (620 mi).
This is simply a layer in the stratosphere containing a relatively high concentration of ozone. Find out where the ozone layer can be found on earth. The Ozone Layer This is simply a layer in the stratosphere containing a relatively high concentration of ozone. The earth's atmosphere is divided into several layers, and each layer plays an important role. The first region extending about 10km upwards from the earth's surface is called the troposphere.