Rings and Maars - John Seach
A tuff ring is a broad flat crater
formed by a phreatomagmatic eruption.
Tuff rings have low rims and slopes
of 3 to 12 degrees.
A maar is a type of tuff ring which
has been affected by sagging so that it lies below the the level of the
A maar is often filled with
water and surrounded by a rim of ejected material that was probably formed
by explosive interaction of magma and groundwater.
Examples of Maars
Lake Nyos (Cameroon)
Suoh (Sumatra, Indonesia)
Karpinsky Group (Kurile Islands)
Ukinrek Maars (Alaska)
Tuff Rings and Maars
Copyright John Seach