The grooves on volcanic rocks are usually parallel, Nowell observed, and only on one side of the rock.
(The grooves on volcanic rocks are usually parallel; observed; Nowell) Context(The grooves on volcanic rocks are usually parallel observed,List([0, 67))):(The grooves on volcanic rocks; are; T:usually; parallel)
The grooves on volcanic rocks are usually parallel observed,List([0, 67))
The grooves on volcanic rocks are usually parallel The grooves on volcanic rocks
observed are
Nowell
T:usually parallel