History of Belmont Lagoon - Summary
Threlkeld’s notes on the Awabakal confirm the Aboriginal mission site (Bahtahbah) was chosen for its proximity to a water body (lagoon) at Belmont circa 1825; he recognized its cultural and communal importance (4) (p.36). Was it as large (40 ha) or as permanent as it is today? The series of early colonial maps shown in Clouten (pp. 36, 81, 178) representing the period 1828-1885 suggest it was still forming, but why wasn’t it shown in Portion 143 of the Parish of Kahibah maps dated 1874 and 1885? These only included codes for swampland or marshes in that proximity. This result raises doubts about a permanent water body (lagoon) there at that time. Perhaps the Awabakal story told to Percy Haslam
that it ‘was not always there’ has a strong physical, if not temporal basis to it.
Besides the most likely geomorphological processes forming this water body at Belmont outlined by Pam Dean-Jones there are some further insights – namely the ‘geologically correct’ identification of the adjacent water bodies, Belmont Lagoon and Lake Macquarie. To do so requires an understanding of a more recent and comprehensive model of clastic coastal depositional environments. As Ron Boyd (40) explains:The area in question at Belmont Lagoon would originally be more correctly called a wetland or a (dune) lake; a lake being an enclosed standing body of fresh or saline water surrounded by land. In my terminology (41) an estuary is a semi-enclosed coastal water body with water and sediment input from both river and marine sources and hence has a connection with the ocean, and brackish to salty water. A lagoon on the other hand has a connection with the ocean, brackish to salty water, but no appreciable freshwater input.
It seems likely that there was a drainage system that operated throughout the Redhead- Charlestown-Belmont area that formed shallow valleys draining to lower sea levels during the Pleistocene Epoch. Around 7000 years ago, the shoreline migrated landwards to its present position, cutting off these valley systems and impounding shallow freshwater bodies (e.g., Belmont ‘lagoon’) behind it. These water bodies would have fluctuated with the groundwater table, high with good rainfall and runoff forming lakes in topographic depressions, and low in drought or even non-existent, forming swamps and vegetated sand flats. Further north it looks as if some of the valleys may have had sufficient runoff to breach the Holocene barrier and flow to the sea intermittently. Further south, there is not so much through-going drainage.
From the Quaternary map, there is an older Pleistocene feature separating the Belmont Lagoon from Lake Macquarie. This is likely a slightly raised feature, perhaps an estuarine beach or low dune. Rather than the bedrock features that confine the wetlands further north, the Belmont Lagoon probably formed by being a depression trapped between a low raised Pleistocene feature on the west and the higher Holocene dunes to the east. With drainage and groundwater input it evolved into a wetland/lake until breached by the canal in the 1940s. So it may have been around (perhaps as an ephemeral feature) for at least 6000 years and perhaps longer. Climate has been quite variable in the Holocene, and this might account for wetter and drier periods when the lagoon was either overflowing, or dried up (e.g. the Little Ice Age in the northern hemisphere).
On the basis of the above definitions Lake Macquarie is a large estuary (it has a tidal inlet at Swansea, is brackish and has numerous fresh water inflows from Cockle Creek, Dora Creek and Wyee Creek). Belmont Lagoon is currently a small brackish estuary with tidal flow in from Lake Macquarie via Cold Tea Creek canal and freshwater inflow from the surrounding dunes and watercourses. Prior to the dredging of the Cold Tea Creek canal connection to Lake Macquarie, Belmont Lagoon would have alternated between a freshwater lake, a swamp and wetland depending on the climate.
This could account for colonial surveyors not recording a lagoon on Portion 143 on their Kahibah Parish maps. Further insights might be gained from official drought and flood records around that time.
Evidence from newspapers and other sources during this same period identified major hydrological changes to its character during droughts, engineered changes and adjacent industrial operations. The once-fresh water ‘lagoon’ has steadily become saline due to tidal influence from Lake Macquarie since the 1940s.
These new geological insights raise some interesting questions. The first is whether 21st century historians will re-identify Belmont Lagoon as a wetland or dune lake. Core samples from this water body might yield suitable data for scientific analysis (42). If the feature was deeper and long-lived, it would have accumulated some sediment over time from different climates and sea levels. Analysis of pollen and spore data can be useful, as well as radiocarbon dates on organic matter like wood and shells. However, given its shallow nature and sandy substrate it may not have accumulated a great stratigraphic record (40). The second interesting question relates to recognizing Lake Macquarie is an estuary on the basis of recent insights on coastal geology. The actual timeframe in which the lake at Belmont became permanent water may be difficult to trace. Newspaper records of flooding and tsunamis along the NSW east coast may be helpful. The comment by Awabakal elders interviewed by Percy Haslam may not be scientific evidence, but included in that verbatim account are other authentic details on flora and fauna now deemed ‘vulnerable’. Perhaps its ‘permanent water’ status began not so many centuries ago. That period may refer to a more seasonal transition from Melaleuca forest and reed swamp still observed near the site today. With drainage and groundwater input it steadily evolved into a freshwater wetland/dune lake. This transition may have begun 6000 years ago, more or less.
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