The chalk was deposited under oceanic conditions at a time when the seas covered most of Britain and much of the continent (between 97 and 65 million years ago).
(The chalk; was deposited; under oceanic conditions; T:at a time) (the seas; covered; most of Britain and much of the continent (between 97 and 65 million years ago; T:a time)
The chalk the seas
was deposited covered
under oceanic conditions T:at a time
most of Britain and much of the continent (between 97 and 65 million years ago T:a time