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	Socio-Economic Characteristics

	Irrigated Crops

	Geology

	Ecological Characteristics

	Wetlands


	LAP Brochure

Last modified:
Monday 20th June 2011

Crop Irrigation Map

LAP Brochure

A report by Brown and Stephenson (1991) contains a comprehensive description of the age, nature, depositional environments and stratigraphic relationships of the sedimentary layers in the Basin.

A summary of the geological sequence in the Mid Murray LAP Region has been extracted from the aforementioned report and is depicted below in Table 1. The surface geology of the Region is mapped in A Study to Underpin a Land & Water Management Plan (AWE, Figure 1.8, page 26) and is available from the Mid Murray LAP Association upon request.

Summary of the geological sequence

Unit	Age	Description	Thickness	Comment
Coonambidgal Formation (Qa)	Late Pleistocene to Holocene	Grey sandy silt and clay	Present over surface of floodplain	Aquitard
Monomam Formation (Qa)	Late Pleistocene to Holocene	Grey to brown sand and gravel	Alluvial deposits in the River valley	Alluvial aquifer
Woorinen Formation (Qdw)	Late Pleistocene to Holocene	Red brown silty sand to sandy clay	Extensive, variable thickness but usually 2-3m	Forms Mallee sand dunes
Bakara Calcrete (Qca)	Early Pleistocene to Holocene	Calcrete rubble or massive sheets	Extensive, usually less than 2m thick	Very low permeability, causes perched water tables
Blanchetown Clay (Qph)	Late Pliocene to Early Pleistocene	Grey-green or red- brown sandy clay, gypsiferous	Extensive, up to 20m thick	Defines ancient course of River Murray
Norwest Bend Formation (Tpn	Late Pliocene	Oyster beds and sandy limestone	Generally less than 5m thick, restricted to narrow north-south zone along the River	Elevated above the water table
Loxton-Parilla Sands (Tps)	Late Miocene to Pliocene	Yellow-brown to red silty sand and gravel	Thickest in south eastern portion, thin or absent to west of River	Major regional unconfined aquifer
Murray Group Limestone (Tml)	Oligocene to Middle Miocene	Pale grey to yellow fossiliferous limestone	Extensive, up to 100m plus thick	Regional aquitard
Ettrick Formation (Toe)	Oligocene to Early Miocene	Grey to green calcareous clay	Continuous, 20-30m thick	Regional confined aquifer
Lower Renmark Group	Eocene to Mid Miocene	Cabonaceous and pyritic sand and clay	Forms continuous blanket over basement, variable thickness up to several hundred metres	Generally forms low permeability base to sedimentary system
Basement	Cambrian- Precambrian	Folded and metamorphosed sediments	Continuous, underlies sedimentary sequence

Hydrogeology

The River valley in the Mid Murray LAP Region is generally incised into the semi-confined regional Murray Group aquifer. Ground water flow discharges from the aquifer into the River valley from east and west.

From deepest to shallowest (oldest to youngest), these aquifers include the:

Renmark Group;
Murray Group; and
Loxton-Parilla Sand aquifers.

The figure below shows:

a regional water table aquifer occurring within the Murray Group aquifer;
potentially) a localised water table aquifer formed within the Loxton-Parilla Sand beneath irrigated areas, underlain by a semi-confined Murray Group aquifer; and
a regional confined aquifer formed within the Renmark Group.