Events 4 - The Crossing of the Blue Mountains

When Governor Macquarie arrived in 1810 and made his first tour to the farms along the Nepean it represented the outer extend of colonial settlement to the west of Sydney Cove. The Blue Mountains represented a difficult barrier to expansion. He encouraged any explorers to find a way.
A number of explorers made attempts to find a way over the mountains, but were often confronted by the high sandstone cliffs. The most celebrated crossing was that done by Blaxland, Wentworth and Lawson in 1813, who followed the ridge lines that the Aboriginal people used as their trading routes.
Macquarie then sent George Evans to survey the route and he went as far as the site of Bathurst. In 1814 he commissioned William Cox to build a road across the mountains, which he managed to complete in just 27 weeks. Macquarie drove over the road in a coach in 1815.

Blaxland, Lawson and Wentworth see the other side

https://en.wikipedia.org/wiki/1813_crossing_of_the_Blue_Mountains

The local connection to the crossing was that Castlereagh and Emu Plains was often the staging area for the crossings. Gregory Blaxland, who lead the successful expedition had his farm nearby at St Marys, while William Cox was something of a local and also built the church and parsonage for Henry Fulton.
Lieutenant Hobby again appears as the overseer of the convict gang building the road and often in charge of construction. He becomes a trusted friend of Cox and a Hawkesbury pioneer landholder.
Aborigonal leader, Yarramundi's son Colbee works as the native guide for the road construction and helps smooth the way with the local Gundungarra people. For this and other work as a guide he is the first native to receive a land grant from a grateful Governor Macquarie.

William Cox