The Cadell Fault is a north-south trending intra-plate
geological fault
Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth ...
in the
Riverina
The Riverina ()
is an agricultural list of regions in Australia, region of south-western New South Wales, Australia. The Riverina is distinguished from other Australian regions by the combination of flat plains, a climate with significant seaso ...
area of
New South Wales
New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...
and
Victoria, in
Australia
Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
. It straddles the
Murray River
The Murray River (in South Australia: River Murray; Ngarrindjeri language, Ngarrindjeri: ''Millewa'', Yorta Yorta language, Yorta Yorta: ''Dhungala'' or ''Tongala'') is a river in Southeastern Australia. It is List of rivers of Australia, Aust ...
and, in quite recent geological times, has affected its course, as well as the courses of the
Edward River
Edward River, or Kolety is an anabranch of the Murray River and part of the Murray–Darling basin, is located in the western Riverina region of south-western New South Wales, Australia.
The river rises at Picnic Point east of Mathoura, as a r ...
,
Wakool River
Wakool River, an anabranch of the Edward River that is part of the Murray River catchment within the Murray–Darling basin, is located in the western Riverina region of south western New South Wales, Australia.
The Wakool River splits from th ...
,
Goulburn River
The Goulburn River, a major inland perennial river of the Goulburn Broken catchment, part of the Murray-Darling basin, is located in the Alpine, Northern Country/North Central, and Southern Riverina regions of the Australian state of Victor ...
and
Campaspe River
The Campaspe River, an inland intermittent river of the northcentral catchment, part of the Murray–Darling basin, is located in the lower Riverina bioregion and Central Highlands and Wimmera regions of the Australian state of Victoria. The ...
. The Cadell Fault is notable due to that impact and has been described as one of the most significant examples of seismic activity changing the course of rivers.
The fault is visible as a continuous earthen ridge along the
Cobb Highway between
Deniliquin
Deniliquin () is a town in the western Riverina region of south-western New South Wales, Australia, close to the border with Victoria. It is the largest town in the Edward River Council local government area.
Deniliquin is located at the inte ...
and
Echuca
Echuca ( ) is a town on the banks of the Murray River and Campaspe River in Victoria (state), Victoria, Australia. The border town of Moama is adjacent on the northern side of the Murray River in New South Wales. Echuca is the administrative cen ...
, and extends further south into Victoria. The fault is likely named after
Francis Cadell, an early European pioneer of the Murray River and river trader.
Geology
The
Australian Continental Plate is generally considered to be one tectonic plate, and is classified as a
craton
A craton ( , , or ; from "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging and rifting of contine ...
- a stable continental region. Within the plate, however, there are a number of fault lines. Those lines are relatively stable compared to the external plate boundaries, but do have the potential to generate significant earthquakes. The Cadell fault is an example of that.
The uplifted Cadell fault forms a bifurcated
scarp, the northern part of which extends for 55 kilometres from Deniliquin to Echuca, with a height of 12–15 metres, and the southern part which extends for 13 kilometres south of Echuca, with a height of about 3–4 metres. The split between the two elements has been formed by the erosion caused by historic Lake Kanyapella (refer to the Goulburn section below). The fault deforms a 200- to 250-metre-thick section of sedimentary rock, which overlies granitic base rock. To the west, the Cadell Tilt Block was formed subsequent to the uplift
Rise and impact on river courses
The lifting of the Cadell fault has had a significant impact on the courses of four major rivers of the Murray river system, and can be described as creating an
inland delta on the Murray River in the area between
Barmah and
Kyalite.
Murray
The uplift of the Cadell fault significantly affected the course of the
Murray River
The Murray River (in South Australia: River Murray; Ngarrindjeri language, Ngarrindjeri: ''Millewa'', Yorta Yorta language, Yorta Yorta: ''Dhungala'' or ''Tongala'') is a river in Southeastern Australia. It is List of rivers of Australia, Aust ...
. Prior to the uplift, the Murray travelled from its current course to the south of
Mathoura
Mathoura is a small town in the Riverina region of southern New South Wales, Australia, in the Murray River Council local government area. At the , Mathoura had a population of 938. At the 2021 census the population was 1,002.
The town's name m ...
, through a
palaeochannel
In the Earth sciences, a palaeochannel, also spelled paleochannel, is a significant length of a river or stream channel which no longer conveys fluvial discharge as part of an active fluvial system. The term ''palaeochannel'' is derived from th ...
now known as Green Gully. It then traversed the plains west of Mathoura to join the current course of the Murray further west.

It appears that Green Gully ceased to be the course of the Murray approximately 45,000 years ago due to the uplift, although it seems to have commenced up to 20,000 years before that (i.e. 65,000 years ago). However, 45,000 years ago it reached a sufficient level to disrupt the flow of the river. Prior to that, the river had been able to maintain its course within the Green Gully, albeit with significant modification to the channel.
The uplift effectively dammed the river and formed a large expanse of water, continuously fed by glacial and snow melt in the
Snowy Mountains
The Snowy Mountains, known informally as "The Snowies", is an IBRA subregion in southern New South Wales, Australia, and is the tallest mountain range in mainland Australia, being part of the continent's Great Dividing Range, a cordillera syste ...
. After a time, the flow found its present course into the Edward River and began to make its way westward via the
Deniliquin
Deniliquin () is a town in the western Riverina region of south-western New South Wales, Australia, close to the border with Victoria. It is the largest town in the Edward River Council local government area.
Deniliquin is located at the inte ...
region. An earlier stream formed by that northward flow is the
Gulpa Creek. During that time, the main flow of the Murray may have also followed the course of the current
Bullatale Creek The Northern lake continued to exist at that time, with evidence of
silt jetties being formed towards present day
Barmah eventually draining to become a series of wetlands and swamps. The present-day
Moira Lake and
Barmah Lake are remnants of the Northern Lake.
Recent research indicates that the current course of the Murray River through the Narrows (also known as the
Barmah Choke) may have originated in recent history, possibly as recently as approximately 550 years ago (approximately 1450 CE). Indeed, local
Aboriginal legend is that the Aboriginal population of the region at the time was instrumental in the formation of the current path of the Murray. Their folklore has it that the local Aborigines carved a channel through the sandbank holding the waters of the Northern Lake back, which then allowed the water to flow into the Goulburn River and form the current course of the Murray. The Narrows were noted by early
squatters
Squatting is the action of occupying an abandoned or unoccupied area of land or a building (usually residential) that the squatter does not own, rent or otherwise have lawful permission to use. The United Nations estimated in 2003 that there wer ...
in the area to be somewhat unusual given its straight sides, compared to the more sloping bank formation of mature rivers
The damming of the Murray by the Cadell Fault directly led to the creation of the Barmah
Red Gum Forests, now protected by the
Barmah National Park in Victoria and
Murray Valley National Park in New South Wales. The damming caused the creation of an alluvial fan (through
aggradation
Aggradation (or alluviation) is the term used in geology for the increase in land elevation, typically in a river system, due to the deposition of sediment. Aggradation occurs in areas in which the supply of sediment is greater than the amount o ...
)
on which the red gum forests established, and the ongoing flooding and draining of the area has led to the arboreal ecosystem present today.
Edward
The
Edward River
Edward River, or Kolety is an anabranch of the Murray River and part of the Murray–Darling basin, is located in the western Riverina region of south-western New South Wales, Australia.
The river rises at Picnic Point east of Mathoura, as a r ...
owes a significant part of its origin to the rise of the Cadell fault. Whilst not studied in as much detail as the course of the Murray, water flowing out of the Northern Lake may have found a previous tributary of the Murray and made its course across to the present day confluence with the
Wakool River
Wakool River, an anabranch of the Edward River that is part of the Murray River catchment within the Murray–Darling basin, is located in the western Riverina region of south western New South Wales, Australia.
The Wakool River splits from th ...
and eventually the Murray at Kyalite.
Today, the majority of the flow from the Murray river flows northward through the Edward, with a lower amount travelling southward into the Murray itself.
Goulburn
Similar to the Murray, the Goulburn River formerly followed a path to the north of its current one, flowing through the Broken Creek and meeting with the former Murray (now Green Gully) somewhere south-west of Mathoura, where it continued westward.
With the uplift of the Cadell, a large lake was also formed south of the Northern Lake, which was the predecessor of present-day
Lake Kanyapella, the remnant of the larger prehistoric lake. Wind-blown, or
aeolian, movement of surface soils created the Barmah Sandhills on the north-eastern edge of the lake. Over time, water flowed from the lake into the Campaspe River, and the Goulburn River changed its course to follow that path. Eventually, erosive water flows drained the prehistoric Lake Kanyapella along the course of the current Murray River.
Campaspe
The path of the
Campaspe River
The Campaspe River, an inland intermittent river of the northcentral catchment, part of the Murray–Darling basin, is located in the lower Riverina bioregion and Central Highlands and Wimmera regions of the Australian state of Victoria. The ...
was less affected by the Cadell fault, but the routing of both the Goulburn and the Murray rivers down the course of the ancient Campaspe, instead of both rivers continuing westwards towards Kyalite, had the effect of making the Campaspe upstream of Echuca a tributary of the new Murray and making its reaches from Kaarimba to Kanyapella part of the Goulburn River.
Ongoing management
As the location of a significant tectonic event, and due to the population and production importance of the region to Australia,
Geoscience Australia
Geoscience Australia is a statutory agency of the Government of Australia that carries out geoscientific research. The agency is the government's technical adviser on aspects of geoscience, and serves as the repository of geographic and geolo ...
has studied the likelihood of further earthquake activity involving the fault. Based on modelling of the maximum credible earthquake, of
moment magnitude scale
The moment magnitude scale (MMS; denoted explicitly with or Mwg, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. was defined in a 1979 paper ...
(MMS) 7.2, the damage incurred would be catastrophic, with over 1,000 square kilometres of land suffering 50% loss of structures. A potentially more likely earthquake, of MMS 6.8, would do less damage in itself but, due to the increased possibility of such an occurrence, may be more of a risk. Those estimates are based on the information presently available, and Geoscience Australia has not specified its confidence in them.
Future movement of the Cadell fault could also affect the courses of rivers, as it has done in the past.
Novel set in this area
Chris Hammer's novel
The Tilt,
is set in this area. The towns have pseudonyms.
Mathoura
Mathoura is a small town in the Riverina region of southern New South Wales, Australia, in the Murray River Council local government area. At the , Mathoura had a population of 938. At the 2021 census the population was 1,002.
The town's name m ...
appears as ‘Tulong’.
Deniliquin
Deniliquin () is a town in the western Riverina region of south-western New South Wales, Australia, close to the border with Victoria. It is the largest town in the Edward River Council local government area.
Deniliquin is located at the inte ...
is Hatheson,
Moama
Moama ( or ) is a town in the Murray region of southern New South Wales, Australia, in the Murray River Council local government area. The town is directly across the Murray River from the larger town of Echuca in the neighbouring state of Vic ...
is Boonlea, and Anglers Reach represents Picnic Point on the Murray.
See also
*
Plate tectonics
Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...
*
Fault (geology)
In geology, a fault is a Fracture (geology), planar fracture or discontinuity in a volume of Rock (geology), rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust (geology ...
References
{{Coord, 35, 49, 0, S, 144, 54, 0, E, display=title
Seismic faults of Australia
Murray River
Rivers of New South Wales
Rivers in the Riverina