I was suprised to see in the second of four videos in the volcano live series that a whole landscape could be completely covered in what looked like a grey coloured snow. It was actually Ryolite. This is a thick lava that when moving and heated, produces large amounts of white ash. This white ash is from sylicate and after a large eruption like puyehue in chile in 2011 can completely cover a landscape.
I would have liked to have seen more depth in the places used. Some were briefly mentioned and I feel there was a lot more information that could have been included that was not. Some were good yet not in depth enough with just this resource to form a strong casestudy.