How can sand dunes be rebuilt naturally?

Are these strong bases, neutral, strong acids, weak acids or weak base household bleach (ph=12.6) fluid in a car's battery (ph of less than 1.0) milk (ph=6.7) stomach contents (ph=2.2) pure water (ph=7)

This is a biological reaction due to a stimulus. i need this quickly !

Darwin’s hypothesis about how life changes over time is now called?