History of Belmont Lagoon: Time before 1820

Awabakal cultural history and geological evidence

This third section examines evidence of the Lagoon’s origins from the rich historical perspective of the Awabakal, who as traditional custodians have occupied this country (27) for millennia. To set the context, the peak of the last Glacial Age (28) was approx. 20,000 years Before Present (BP). The southern half of Australia was arid, cold and windy; it had small glaciers. Aboriginal populations sought refuge in small habitable (well-watered) areas. By about 10,000 years BP they would have noticed extreme changes to the environment, for example the sea level rising visibly on a weekly basis. Steppe grassland and open savannah of south-east Australia were replaced by forests. From 9,000-6,000 years BP there were higher temperatures and from 8000-4000 years BP there were periods of maximum rainfall. Of interest to this study are the recorded changes in an ephemeral freshwater wetland/permanent lake in the New England region during this Holocene period (29)

Cultural anthropologists and others (e.g., Rev. Threlkeld, 200 years earlier) have compiled information and artefacts showing Aboriginal people occupied Awaba and managed its natural resources for at least 6000 years. This period fits well with geological evidence of the end of the last sea level rise (7000 years BP).

As Christopher Morton explains: Most of the wetlands along the coast formed after a wave of sand was pushed up as a barrier. These Barrier Dune systems cut off low level area allowing them to be filled with sediments and vegetation, creating these wetlands (30). 20th century researchers (31) collected archeological evidence on communal life of the Awabakal, custodians of Awaba (Lake Macquarie and surrounding area). Campsites have been identified around Belmont Lagoon where food sources were plentiful. Weirs were constructed to catch fish in small tidal channels. Dune areas provided plants and terrestrial animals. They were also used as mealtime gathering spaces. (Bonhomme, 1994 as cited in Godden Mackay Logan, 2009, p.5) (5) Similar archaeological findings were reported (32) at Jewells Swamp. The lagoon was a central part of Awabakal community life (33), and an important Dreaming site in their culture. The lagoon’s creation story related by Professor John Maynard shows great empathy between the moon-man and Awabakal.

But the question remaining is: has this lagoon been in existence for at least 6000 years or has it been formed more recently, as colonial maps suggest? Tsunamis and large storms (such as east coast lows) can change beach landscapes dramatically and relatively quickly. Excavations of deposits formed 12-15 m above the high water line at Swansea Heads indicate the effects of a huge storm surge or tsunami approx. 3000 years BP (34).

Further insights on the Awabakal Dreaming story of the Creation of Belmont Lagoon are provided by Percy Haslam (35), a journalist with a long association with The Newcastle Morning Herald and Miners’ Advocate and a deep passion for the language, culture and history of the Awabakal. On the legend When the Moon Cried he wrote: But, according to Awabakal aborigines, the lagoon was not always there; that there was a time when the area now covered with water was part of the general landscape of scrub and brush, plus extensive patches of thick grass on which the New Holland mouse once thrived

Reference to ‘extensive patches of thick grass on which the New Holland Mouse (36) once thrived’ offer several clues. The ‘thick grass’ may have been Kangaroo Grass (Themeda australis); tufted grass to 1.2 m tall, most commonly found in ungrazed to lightly grazed areas that have not been ploughed (37) . The ‘general landscape of scrub and brush’ may well have been coastal vegetation seen today in marshes and swampland adjacent to the Lagoon, for example Acacia, Banksia, Casuarina and Melaleuca spp.

The New Holland Mouse (Pseudomys novaehollandiae) is reported in Coastal Dune Dry Sclerophyll forests (Coastal sand-Apple Bloodwood forest and Smooth-barked Apple healthy open forest) on sands of NSW North Coast, but not in the Belmont area. Its NSW conservation status is Vulnerable. Together these clues suggest the lagoon might have formed within the past 1000 years.

Geological history: evidence from maps of the Quaternary Period

Further clues to Belmont Lagoon’s formation can be found on geological and soils maps of the NSW coastline (38) . These maps effectively ‘collapse’ the history of land and sea movements over millions of years using codes for bedrock and soils deposited during the Quaternary Period. It began with deposits being laid down along the coast in the (older) Pleistocene Epoch 2.6 million-11,700 years BP, followed by the (current) Holocene Epoch after the last Glacial Period ended. A map for coastal Newcastle Hunter enables a search for deposition clues and the likely geological formation of Belmont Lagoon.

As elaborated by Pam Dean-Jones (39) Much of this area’s ‘natural terrain’ was modified extensively by sand mining activities, so key landform clues are missing. Relying on stratigraphy of remaining sand deposits means considerable uncertainty. On the coastal barrier systems between Swansea Channel and Redhead:

• Pleistocene deposits are located landward of the Holocene deposits, in the north-western part of the system. Initial Pleistocene deposits relate to a period of high sea levels (2-3 m higher than today). Shell deposits of this age also occur in the Hunter estuary and sand deposits of similar age occur inthe ‘inner’ barrier of Stockton Bight. However, wind-blown deposits (such as the bedrock mantling dunes described below) are much younger. These were likely formed by reworking of the old beach-barrier sands during the last glacial period, approx. 17,000 years BP when sea levels were 130 m below today and this area was dry land, 20-30 km from the coast.
• Holocene estuary deposits (eg. a tidal delta flat) are south of the Pleistocene sands - around Cane Point.

As mapped by Geoscience NSW, Pleistocene deposits around Belmont include:

• Pleistocene back barrier flat (Qpbf), forming the shoreline of what is now Belmont Bay;
• Pleistocene bedrock mantling dunes (Qpbdr) - wind-blown sands from the last glacial period.
• Pleistocene dunes with indurated sand (Qpbd). These also are likely to be of last glacial age. The area mapped as this material is south of Belmont Lagoon. The ‘indurated sand refers to the B horizon of a dune podsol soil profile which has been deeply weathered over a long period, developing a strongly differentiated soil profile. (The A horizon of these podsol profiles is what glass sand-miners prized – clean, white, well-rounded, fine quartz sand). Holocene deposits began to accumulate as sea level returned close to its current position. As sea level rose, it drowned old shorelines to the east and swept sand landward. From around 8000 years ago shorelines began to accrete as Holocene beach ridges (a series of beach and frontal dune deposits). In some areas (e.g., Stockton Bight), there is a clear ‘inter-barrier depression’ separating the old Pleistocene sand deposits from the Holocene deposits. The inter-barrier depression is low lying and includes wetland habitats. The Holocene back barrier flat was deposited seaward of the inter-barrier depression.
• At Belmont, the Holocene back barrier flat sediments (Qhbf) are mapped immediately east of the remnant of the Pleistocene back barrier flat.
• The map does not show Holocene beach ridges, but the current width of the barrier between the modern beach and the back barrier deposits suggests that there may have been a relatively narrow sequence – perhaps less than ten ridges. All these have either been reworked by wind or removed by sand miners.
• The map does show Holocene barrier dune (Qhbd) and mobile dune (Qhbdm). The Holocene barrier sand at the northern end of Nine Mile Beach was reworked by wind into long walled transgressive dunes oriented to the south east (the dominant wind direction). Some dunes that were mobile in the past had stabilized and were well vegetated. This is similar to dunes towards the northern end of several coastal barriers systems (e.g. on the Central Cost, and at Stockton). These transgressive dune sequences on other barriers appear to have been initiated approx. 4500 years ago, 2300 years ago and 500 years ago. There are few dates on the dunes to provide a robust dated sequence.
• Qhbb is the modern beach and frontal dune system.
• Two ‘lakes’ (or wetlands) mapped as Holocene Barrier Lake (Qhbk) are mapped south of Belmont Lagoon, but in similar terrain and similar Pleistocene transitioning to Holocene dune sequences. They are however close to the remnant tidal delta flat deposits and may once have had some connection to the lake entrance.

In short, Belmont Lagoon sits on these back barrier flat deposits and is connected to freshwater wetlands (Qhs) extending north (Jewells Swamp) – between the Pleistocene dunes over bedrock and the Holocene mobile dunes. This suggests there are three potential scenarios for the development of the lagoon:

• It is the remains of an inter-barrier depression, between the Pleistocene wind-blown sands and the early Holocene beach ridges. This low-lying area is fed by freshwater draining from the bedrock catchment to the north (some of which have sand mantles and would have surface and groundwater flows)
• The lagoon is perched on indurated sand of late Pleistocene age (again low-lying, potentially a deflation basin landform left by the removal of wind-blown sand to form the rock mantling dunes). It could also be perched on peat.
• The lagoon is within a shallow depression formed by the Holocene transgressive dune sequences. Some of the sediment in the bed of the lagoon will be material washed in through the wetlands to the north. Some will be organic material accumulating on the wetland and some could be wind-blown sand at the landward margin of the transgressive dunes coming from the east. The lagoon may have overflowed to the lake in the past (after a period of heavy rain), but it could also have been cut off and perched above lake level until the channel at Cold Tea Creek was cut. The area south of the lagoon and around Pelican and Swansea is all either tidal delta flat or back barrier flat of Holocene age. All of this land is very close to sea level. The lake entrance may have moved around a bit in this area. It is known to have moved a little north of its current position (held by the training walls), which is a reason why the dunes in the southern corner at Blacksmiths are low.

The pattern of back barrier flats at the southern end of the Holocene barrier and higher reworked dunes at the northern end is repeated on several barrier systems along the NSW coast and is linked to the dominant south east swell. Longshore drifts tend to take sand north. The northern ends of beaches are also more exposed to waves and wind – more energy.

This work by Lake Macquarie City Library is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License