Halliday &
Matthiessen (2004: 439-40):
[Consider] we saw the turning of the boats. Here the process has been nominalised at the word rank, with turning as noun … . The structure is that of a nominal group having [a] prepositional phrase with of as Postmodifier; the Complement of the of phrase corresponds to what would be the Complement if the process was realised as a clause. … Where there would be an explicit Subject, if the process was realised as a clause, what corresponds to this is the ‘possessor’ of the process, as in his handling of the situation …