The renewable energy source is Hydroelectricity.
Answer:
The universe is expanding.
Explanation:
Following the theory that the universe was originated from a single heavily compressed and super hot point, and quickly expanded itself to what we see today, we can assume that the universe is still expanding.
According to the big bang theory, the remnants of that explosion still cause the planets and elements in the universe to move farther from one another, allowing the universe to continue its expansion. This expansion has become slower and slower over billion of years, and the scientific community doesn't know for sure if the expansion will go on forever, or if it will have an end.
They allow magma to burst between cracks, and they cause blocks of rock to seperate and form new plates.
None of the Plains tribes were originally Plains tribes - they all migrated into the Great Plains when horses became available. Living on the vast, empty grasslands was almost impossible without horses, which made following the herds a practicable lifestyle.
Previously most of the Plains tribes had lived in the northern woodlands or east of the Missouri river
