OPR Rail Development – Vegetation and Flora Assessment
substantially metamorphosed rocks; granulites and some felspathic quartzite; large granite intrusions
The geology of Beard’s (1976) Murchison region is dominated by the Archaean Yilgarn Block (also
known as the Yilgarn Craton), which forms the nucleus of the Western Australian Shield. Gneisses
and granites are the major components of the Yilgarn Block, with minor infolded belts of
metamorphic sedimentary and igneous rocks. Metamorphic rocks are composed of various volcanic
and sedimentary materials including: ultramafic and mafic rocks (essentially basalts), acid lavas and
tuffs, chemical sedimentary rocks such as banded ironstone, jaspilite and chert, and clastic
sedimentary rocks comprising shale, siltstone, sandstone, greywacke and conglomerate.
Metamorphic belts are mineralized and tend to form ranges of hills, as they are harder and more
resistant than gneiss and granite ‐ the latter generally underlie plains, particularly sandplains. The
major soil type present in the Murchison region is shallow earthy loam overlying red‐brown hardpan.
The Upper Murchison subregion of Beard’s (1976) Murchison region is described as generally hilly
and undulating terrain, with shallow soils and granite exposure in the hills. The Weld Range and the
Jack Hills are the main ranges of the subregion, and are formed by resistant metamorphic rocks
(Beard, 1976). These greenstone belts exhibit banded ironstone formations (Elias, 1982). Curry et al.
(1994) describe the Murchison River catchment and surrounds as an area dominated by granite‐
greenstone terrain, while very flat plains derived from colluvium and alluvium widely separate the
hill ranges. Soils are predominantly shallow, sandy and infertile, and are underlain by red‐brown
siliceous hardpan across most of the lower areas.
The terrain of the Yalgoo subregion of Beard’s (1976) Murchison region is undulating and moderately
dissected, with small remnants of the Tertiary land surface existing as sandplains. Low ranges of hills
are created by metamorphic rocks. An inventory and condition survey of the Sandstone‐Yalgoo‐
Paynes Find Area was carried out by Payne et al. (1998). They describe the area as dominated by
granite‐greenstone terrain, with gently sloping pediments widely separating occasional ranges.
Sheetflood alluvial plains (very gently inclined) are upslope from salt lakes. Most soils are
characterized as shallow, sandy and infertile, generally with the lower areas underlain by red‐brown
LAND SYSTEM AND SOIL‐LANDSCAPE SYSTEM CLASSIFICATION
Rogers (1996) conducted an inventory of soil and land resources of the Geraldton agricultural region,
covering an area of approximately 20,600 km
. The Study Area incorporated the Shire of Mingenew
Northampton. Fifty‐one soil‐landscape systems are described, based on geology, landform and soil
characteristics in this area.
The Freehold section of the Study Area crosses 10 of the soil‐landscape systems mapped in the
Geraldton agricultural region and a summary of these soil‐landscape systems is provided in Table 2.4.
The most commonly occurring soil‐landscape systems in the Freehold section of the Study Area were
the Dartmoor (27.4%), Eradu (20.1%) and Binnu Systems (14.3%). The soil‐landscape systems with
the highest percent of the total system area contained in the Study Area were the Greenough
(11.8%), Moresby (7.5%) and Dartmoor Systems (6.7%).
Gently undulating sandplain with numerous dune ridges.
Level to gently undulating sandplain.
Level to gently undulating plain and weakly dissected long slopes, much as a relic drainage
Level to gently undulating sandplain. Drainage lines absent with a few soaks.
River beds, terraces and alluvial flats associated with Greenough, Murchison, Hutt and Chapman
Flat‐topped ranged and isolated mesas. Flat to gently undulating summit surfaces, moderate to
steep side slopes and gently inclined footslopes.
Lateritic breakaways with spillway sands. Long gentle slopes broken by low gravel ridges and
Casuarina System (gently undulating sandplain) to Tamala System (coastal limestone hills).
Narrow valleys with gently undulating to rolling rises and low hills with an integrated drainage
pattern. Rock outcrop common on hillcrests with long gentle slopes and alluvial terraces
associated with local rivers. Forms much of drainage basin of Chapman, Bowes, Oakajee and
Undulating to rolling rises with narrow valleys and an integrated drainage pattern, drained by
Series of low hills parallel to the coast immediately behind the Quindalup System. Well drained
calcareous black sands, neutral reddish brown sands and neutral yellow sands.
Source: Rogers (1996)
Land systems are described using the biophysical characteristics of geology, landforms, vegetation
and soils (Curry et al., 1994; Payne et al., 1998).
Curry et al. (1994) undertook a regional inventory of the Murchison River catchment and surrounds
to document the land systems present and the condition of each. The Study Area covered
, extending between Meekatharra and Mount Magnet in the east, to the catchments of
of the Sandstone‐Yalgoo‐Paynes Find area to document the land systems present and the condition
of each. The Study Area covered approximately 94,700 km
and Payne et al. (1998), these land systems are described in Table 2.5.
The most commonly occurring land systems in the Pastoral section of the Study Area were the
Yanganoo (19.8%), Tindalarra (16.3%) and Challenge (9.6%). The land systems with the highest
percent of the total land system in the Study Area were Yarrameedie (10.3%), Weld (9.7%) and Millex
as Figure 2.4. The soil‐landscapes are mapped as Figure 2.5 and the land systems are mapped as
Figure 2.6 to Figure 2.8.
Table 2.5 – Land Systems of the Study Area
Hardpan wash plains interspersed by low sandy (wanderrie) banks supporting tall shrublands of
mulga with understorey shrubs on the hardpan plains and non‐saline shrubs with perennial
grasses on the banks.
Major riverine plains with active lower floodplains flanking channelled watercourses; supports
perennial grasses; severely degraded and eroded in many areas.
Gently sloping gritty and sandy‐surfaced plains with granite outcrops and minor breakaways,
Calcreted drainage zones on hardpan; alluvial plains with raised calcrete platforms dissected by
major flow zones and channels, supporting variable mostly non‐halophytic shrublands and
calcareous shrubby grasslands.
Tributary floodplains with shallow, erodible duplex soils on red‐brown hardpan, more or less
degraded and eroded.
Hardpan wash plains with long, interconnected wanderrie banks supporting mulga and wanderrie
Ridges, hills and footslopes of various metamorphosed volcanic rocks (greenstones), supporting
Undulating yellow sandplain system supporting dense mixed shrubland with patchy mallees.
Hardpan wash plains with variable dark gravely mantling and weakly groved vegetation; minor
Elevated, gently undulating red sandplains edged by stripped surfaces on laterite and granite; tall
acacia shrublands and understorey of wanderrie grasses (and spinifex locally); replaced by more
extensive areas of Bullimore land system to the south‐east and Sandplain land system to the
Quartz‐strewn stony plains and low rises with outcropping granite, gneiss and schists; supports
Saline and non‐saline calcreted river plains, with clayey flood plains interrupted by raised calcrete
platforms supporting diverse and very variable tall shrublands, mixed halophytic shrublands and
Plains on granite, with irregularly distributed low sandy banks and saline alluvial plains lightly
Level or very gently undulating stony plains on hardpan and granite with irregularly distributed
Low hills, ridges and outcrops of granite, gneiss and quartz above convex, quartz‐strewn
Greenstone hills supporting Acacia shrublands and Eucalypt woodlands.
Undulating plains of sandy‐surfaced laterite and weathered granite with low remnant plateaux,
Granite hills with exfoliating domes and extensive tor fields, supporting acacia shrublands.
Loamy plains surrounded by sandplain supporting York gum woodlands.
Extensive, gently sloping stony and sandy plains on granite and gneiss below saline footslopes of
shrublands with understorey non‐halophytic and halophytic shrubs.
Prominent ridges of banded ironstone, dolerite and sedimentary rocks sporting bowgada and
Very gently inclined hardpan wash plains with narrow drainage lines and fairly saline narrow
narrow tracts of snakewood and bluebush; a major wash system in the Greenough River
Gently undulating gravely plains on greenstone, laterite and hardpan, with low stony rises and
minor saline plains; supports mulga and bowgada‐dominate shrublands, with dense mulga groves
and patchy halophytic shrublands.
Sandplains and stripped granite or laterite surfaces with low fringing breakaways and lower
plains; supports bowgada shrublands with sparse wanderrie grasses, mulga shrublands and minor
Rugged ranges and ridges of mainly Archaean metamorphosed sedimentary rocks; supports
Low greenstone hills with occasional lateritic breakaways and broad stony slopes, lower saline
stony plains and broad drainage tracts; supports sparse mulga shrublands with patches of
Flat hardpan wash plains, extensively uniform and carrying light to moderate mantles of small
Almost flat hardpan wash plains, with or without small wanderrie banks and showing variable
Undulating stony interfluves, drainage floors and pediment (foothill) plains below major ranges of
Mainly flat saline floodplains on the Greenough and Sandford Rivers supporting halophytic
shrublands dominated by samphire, saltbush, snakewood and spiny snakewood.
Source: Curry et al. (1994) and Payne et al. (1998)
Proposed Rail Alignment
Proposed Project Area
Name: GDA 1994 MGA Zone 50
Projection: Transverse Mercator
Datum: GDA 1994
Unique Map ID: A038
Unique Map ID: A037