Valles Marineris

[aerohead]

I've been reading about the Himalaya. PhD John F. Shroeder, Jr., Professor of Geology & Physical Geography, University of Nebraska, Omaha.
He attributes boulder deposition to
Floods
Landslides
Glacier Advances
and Iceberg rafting
He cites enormous 'Pujab erratics', large blocks of exotic crystalline rock of the plains of Attock, carried hundreds of miles from the Patro and Raikot Glaciers, by dam breaks along the major river in between.
Like the New Mexico caldera blow-out.