Halliday & Matthiessen (2014: 414):
As the examples illustrate, verbs of motion are phased temporally to indicate durative motion (‘continue to go’) and spatially to indicate directed motion (‘go’ + direction). With the second type, the verb often denotes some specific manner of motion such as flit and clamber in the examples above; the phrasal verb thus makes it possible to combine manner and direction: verb [manner] + adverb [direction]. Similar patterns are found in languages with ‘serial verb constructions’ and ‘verb compounding’. Direction occurs naturally with motion, of course; but it may also be used as a phasal extension verbs of other kinds, as with direction of perception:
Frodo and Sam gazed out in mingled loathing and wonder on this hateful land.
Blogger Comments:
To be clear, on grammatical criteria, gaze and gaze out serve as behavioural Processes, not mental Processes of perception. For example, neither affords a Phenomenon — * gaze (out) this hateful land — but instead, like some other behavioural Processes, can take a Location circumstance that indicates the orientation of the behaviour, such as gaze (out) on this hateful land.