The cave-openings scattered throughout the southern section of the Isendale provide the Orcs passage onto the landscape.
'Orcs have begun to emerge from several cave-openings that lie at the base of hills along the southern ridgeline of the Isendale. This is surely how they are bringing aid to the Dunlendings.
'If you would, travel back up the switchback and find these caves. Collapse the entrances and deny the Orcs passage onto the landscape.'
The cave-openings can be found along the hills east of Innoth's encampment.
Innoth has asked you to collapse the cave-openings from whence the Orcs have been issuing.
Innoth is at his camp near the Isen, west of the caves.
You should return to Innoth with news of your success.