Geologically the Mountain area is made up of old sedimentary Hawkesbury sandstone deposits and some basalt intrusions, about 1000ft. above sea level, with steeply eroded gullies defining its areas of agricultural land use and transport access.
This resulted in the the area developing by way of a number of discrete localites and villages. More information here.
Home of the Darkinjung people, the region is criss-crossed by real and mythological “pathways” which still can be discovered in sequences of rock engravings, paintings and stencils in rock shelters, grinding grooves, middens, and abandoned tools, as well as in the remnants of cultural tradition handed down through stories.
European occupation of the Mangrove Mountain districts, came surprisingly late given its proximity to Sydney, as the relatively inaccessible terrain limited opportunities for farmers to get their produce to market in Sydney profitably.
The first farmers and timber getters came to the mountain area from both the east and the west, from the Gosford-Erina-Narara area to the east, and from Mangrove Creek to the west. Both of these ‘settlements’ were established in the early 1800s and were first accessed by water from Sydney.
Mangrove Creek valley was farmed in early colonial times, with a variety of crops, including wheat. By the late 1800s, many of the families from “down the creek” had taken up land “on the mountain” alongside newer residents, some of whom had anticipated better transport to the area with a rumoured railway line.
The railway of course did not come through the mountain, and so most of the mountain produce was carted to Mangrove Creek, then carried by boat to Brooklyn. This continued well into the 20th Century, making the creek the main route to the Mountain. Lower Mangrove and Spencer on the Hawkesbury are still considered part of the Mangrove Mountain community.
Many crops were experimented with in the early agricultural development of the district, including apples, grapes and grain, but in the end the region became best known for citrus. Farms often combined citrus orchards with passionfruit plantings supplemented by tomatoes, beans and other vegetable crops. By the 1960s the region was one or the biggest citrus producing areas in Australia.
Since the demise of the citrus industry, many other ventures have been tried. Chicken farming continues to be an important part of this, in spite of the devastating outbreak of Newcastle disease in 1999. Stone fruit, avocados, plant nurseries, livestock production and seed-stock enterprises, vegetable growing, cut-flowers and deer farms can all be found on the mountain, along with some remaining citrus orchards.
The quarries are playing an increasingly important part, including more recent (and contentious) plans to expand sand-mining. Equestrian and other horse activities are also increasing
Agriculture and rural life continue to be the defining attributes of the culture of the Mangrove Mountain districts, however, despite the effect of changing social and economic conditions.