This gap is most likely the result of episodes of mountain-building and erosion which removed the rocks formed during this time period.
(This gap; is; most likely) (episodes of mountain-building and erosion; removed; the rocks formed during this time period) (the rocks; formed; T:during this time period)
This gap episodes of mountain-building and erosion the rocks
is removed formed
most likely
the rocks formed during this time period
T:during this time period