WfHC - cover page (not to be used with pre-printed report ... - CSIRO

Working Knowledge at Oriners Station, Cape York
firm, occasionally hardsetting. Well drained, highly permeable, stable
(Biggs and Philip 1995a; Biggs and Philip 1995b).
o Combined: Depressions, Ridgelines, Plains (Atlas of Australian Soils):
Mr11 (Atlas of Australian Soils): Gently undulating plains consisting
of low very broad sandy rises (interfluves) and many sharply defined
shallow drainage depressions (dambos) that become less prominent in
the northern parts of the unit. Well-defined swamps (pans) are also a
feature. The dominant soils of the rises are sandy yellow earths
(massive and structured earths). Other sandy earths are commonly
associated. Some soils have ironstone nodules at depth. On higher
ridges there may be areas of sandy red earths or deep sands. On
some lower slopes adjacent to the drainage depressions deep sandy
duplex soils (yellow and yellow-grey duplex soils) or deep bleached
sands occur. The drainage depressions have sandy to loamy grey
duplex soils and bleached grey. (Figure 49 (Isbell, Webb et al. 1968;
Bureau of Rural Sciences (BRS) 1991).
Ca39 (Atlas of Australian Soils): Undulating to gently undulating
plains with prominent shallow drainage depressions: dominant soils
are deep mottled bleached sands, with other deep sands also
occurring. Associated are deep sandy yellow earths (massive and
structured earths). Sandy or loamy bleached grey earths and loamy
mottled duplex soils (yellow and yellow-grey duplex soils occur in the
shallow drainage depressions. Data are fairly limited (Isbell, Webb et
al. 1968; Bureau of Rural Sciences (BRS) 1991).
MT12 (Atlas of Australian Soils): Gently undulating plains consisting
of low sandy rises (interfluves) and broad shallow drainage
depressions (dambos); small isolated dissected sandstone or lateritic
mesas occur in parts of the unit: dominant soils of the rises are sandy
bleached mottled grey earths (massive and structured earths), with
associated sandy grey earths, sandy yellow earths and bleached
sands. Most of these soils are underlain by weathered sandstone at
moderate depths. Occasional higher rises have sandy red earths. The
shallow drainage depressions (dambos) have loamy bleached grey
earths and loamy duplex soils (yellow and yellow-grey duplex soils).
Adjacent to larger streams are small levees of loamy or sandy red
earths. The small dissected mesas are remnants of unit Bz17. (Figure
49 (Isbell, Webb et al. 1968; Bureau of Rural Sciences (BRS) 1991).
Of interest to note in many of these soils is the common presence of soft mottles and hard
pisoliths (nodules) due to solute accumulation during wetting and drying cycles. Mottles often
harden into nodules (ferricrete, calcrete, silcrete) once permanently oxidized by atmospheric
exposure due to either a lowering of the water table and/or exposure through sheet or gully
erosion. The side slopes of shallow depressions or gully scarps and floors are preferential
zones of accumulation of cations (e.g., iron, manganese, calcium, silca) through local soil
development processes (relative accumulation (McFarlane 1991)) and lateral groundwater
input (absolute accumulation (McFarlane 1976)) or both (Goudie 1973; Goudie 1984). The
relatively recent formation (hardening) of ferricrete nodules can be seen in many deep gullies
that formed over the last 100-yrs as a partial result of land use disturbance. The rapid
exposure of massive alluvial soils after gully erosion promotes the oxidation of soil mottles
and hardening into nodules of ferricrete and calcrete, which form surface lags of coarse
gravels on gully scarps, floors, and other eroded or stripped surfaces (Grimes 1979; Pain
and Ollier 1992; Shellberg 2011).
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