At what approximate altitude in the atmosphere can stratospheric ozone be found?
a) 10 km
b) 30 km
c) 70 km
d) 100 km

According to the earth science reference tables, during which geologic time period were the continents of north america,south america, and africa closest together?

Mexico city is an example of how humans alter their environment because it was a. one of the world’s largest cities b. built on drained and filled lake beds c. built after conquest by the spanish d. once the capital of the aztec empire

How have citizens in aralsk adapted to the changes brought about by the shrinking of the sea?