The funky hills-without-valleys are all limestone, and rainfall collects in the depressions between the hills and percolates down through the porous rock, turning into carbonic acid which then carves out caves below.
(The funky hills-without-valleys; are; all limestone) (rainfall; collects; L:in the depressions between the hills) (rainfall; percolates; down) (carbonic acid; carves out; caves below; T:then)
The funky hills-without-valleys rainfall rainfall carbonic acid
are collects percolates carves out
all limestone
L:in the depressions between the hills
down
caves below T:then