Castlereagh River
The Castlereagh rises 20 km west of Coonabarabran in the heart of the Warrumbungle mountains at an elevation of about 850 metres. From its commencement upstream in the mountains the river initially flows east through the town of Coonabarabran. It then arcs round south and southwesterly to the village of Ulamambri, then south to Binnaway, and SSW to the small town of Mendooran which lies at the eastern side of the river's hook-shape. From here the Castlereagh flows in a westerly direction at the flattened bottom of the hook and then turns north-westerly towards the town of Gilgandra. From Gilgandra it continues to run northwesterly across the plains through Gulargambone and Coonamble, then continuing across expansive plains, with no urban centres, where elevations are less than 200m, until it joins the Macquarie River at its uppermost reaches beyond the Macquarie Marshes. Its confluence with the Macquarie is about 65 km SW of Walgett. Not far from the Castlereagh/Macquarie confluence the Macquarie itself joins the Barwon River at a place about halfway between Walgett and Brewarrina.
Castlereagh River
In early July, the party returned from the Macquarie Marshes to Mt Harris, 48 km (30 miles) N-NW of present-day Warren. Seemingly unable to further follow the course of the Macquarie, Oxley had to change his plans. He decided to send Evans ahead, with a small party, to scout a north-easterly route across the plains, and report back. Beginning on 8 July 1818, Evans would end up traversing a large loop, north-easterly then south-easterly, then westerly and back to his starting point. In the north-easterly direction, he first crossed the Castlereagh River around Combara, between Gulargambone and Coonamble. The party then continued on a shallower east-north-easterly direction until reaching the foothills of the Warrumbungle Mountains. From here, Evans turned south-westerly to head back to Oxley's encampment at Mt. Harris, travelling across ‘an open plain, over which was rather better travelling than we had latterly experienced’. This route brought his party back to the Castlereagh River at a point south of his first crossing, in an area between the future villages of Armatree and Curban (10 miles apart). As he approached the Castlereagh River he described the country as
‘low and wet’, with the journey being ‘dreadfully bad and marshy’. The country he was crossing over is today considered rich pasture and farming land, covering the areas known as Tonderbrine, the western side of Tooraweenah, the Yarrandale area and Hillside.