Answer:
Defletion hollows: Defletion hollows are ever wind has removed sand down to a level where a layer of particles is too heavy for the wind to move stabilises the sand and prevent the surface being lowered further. It's also known as blow out dune.
Explanation:
Sorry ,I only know about this so i can't tell u of others
Answer:
4500 years old
Explanation:
Line up 50 to the graph on the y axis and it gives a x value of 4500
