Can you answer these simple science questions?

Question

1) How can a valley glacier form in an area that is tropical or subtropical?

2) How does over farming and over grazing make some lands vulnerable to wind erosion?

Answer 1

The world has gone through some significant changes in temperature during the last 100 thousand years or so.  Areas of the world that are tropical now were once (even several times) under kilometers (deep that is) of ice.  Most of Europe and North America were under huge sheets of ice.  As those ice sheets advanced and retreated over thousands of years, they tended to dig (or plow) valleys.  That's how you get valleys created from glaciers that are no longer around.

Soil is held together by the vegetation growing on it.  The vegetation keeps the soil moist and protects it from the sun, the rain, the wind, the cold, ... If you remove or change the vegetation and, without proper protection, the soil could quickly dry out and then be blown around by the wind in a process known as "wind erosion".

Answer 2

1) High altitude valleys can easily be permanently cold enough to maintain a glacier, no matter what the prevailing climate in the region.

2) Overgrazing and farming reduces the plants in an area, the roots from these plants are what holds moisture and physically binds the soil together, the plant also acts as a buffer for the wind. Without it, soil dries, and is blown away more easily.