Answer:
The basin rests 282 feet below sea level, and lets in the hot sun to creep into the valley, while getting very little rain.
So I would say, the amount of precipitation or temperature has the biggest effect.
*I do not know for sure, I just took a shot at it
Answer: Glacier
Definition:
a slowly moving mass or river of ice formed by the accumulation and compaction of snow on mountains or near the poles.
Your answer is, flood plain.
Answer:
I believe that they are decendents of the earliest split from ancient Eurasian populations.