Which preposition to use with gascoyne

to Occurrences 1%

He went by way of the Murchison, and crossed over the Gascoyne to the Ashburton, which he followed up to its head.

with Occurrences 1%

Finding that the Murchison was leading us too much to the eastward, the object of the expedition being to reach the Gascoyne with as little delay as possible, we quitted the river on a north-north-east course for about eight miles over a tolerably grassy plain, in some parts open, with atriplex and samphire, and in others rather thickly studded with acacia and melaleuca.

Which preposition to use with  gascoyne