Only two markers of human activity are evident in the stratosphere.

They are indicated by .

Select one:
a. the condition of the ozone layer and the presence of spy planes
b. the flight of rockets and transmission of radio signals
c. the weather that we experience and commercial airplane flight

d. the presence of satellites and the International Space Station

1. seamount a raised footwall block between normal fault creates this 2. syncline break between rocks where a hanging wall rises relative to a footwall 3. hot spring on rolling hills, this a dip between hills 4. volcanic neck created when a block with hanging walls slips down between normal faults 5. caldera underwater volcano that never reaches above sea level 6. horst natural hot water on earth's surface containing many minerals 7. graben underwater volcano whose top is eroded flat by waves 8. crater less than a mile in diameter; looks like a bowl at the top of a volcano 9. guyot magma that filled the central vent that remains after the volcano has eroded 10. reverse fault over 1 mile in diameter; looks like a bowl over a volcano