Why did the silurian period end? what changed?

Air masses are characterized by various properties including temperature humidity air pressure and wind speed. which of the following air masses is associated with low relative humidity and high air temperature ?

Match the following items. 1 1 (4,4) 2. (-4,-2) 3. (3.-6) 4. (-4, 6) 5. (1,5)

1. crust 1 the metallic layer at the earth's center 2. inner core 3 the firm layer between the crust and the asthenosphere 3. lower mantle 2 the layer surrounding the inner core 4. asthenosphere 4 the semi-solid layer between the top layer and the upper mantle 5. upper mantle 5 the layer between the asthenosphere and lower mantle 6. top layer 6 the earth's outermost layer 7. outer core 7 the hottest part of the mantle