R! Geomorphic category Cainozoic deposits (coarse- to medium- Cainozoic deposits (medium- to fine-textured) textured) Land system CpCp CpXM part, CpM part CpXM part, CpM part, CpBl part, CpG part CpG part CpBl part, CpBXM CpG part Terrain Very gently Almost level to very gently undulating—uneven microlief (30-90 cm) in some areas undulating

Soils Uniform sandy Massive earths, Eb (a) Sandy duplex soils, Mosaics of massive Cracking Gilgaied a soils, Fa, Fb (Ec, Ed) Df, and massive earths, earths, Eb, Ec; clay soils, cracking > 1 Ec duplex soils, Da; Cb clay soils, Ca r (b) Sandy and loamy brown and grey- o duplex soils, Df, Da brown soils, Be, Bb, (c) Duplex soils, Db Ba; and gilgaied clays, Ca tn H Vegetation (a) Angophora Box, silver-leaved (a) Brigalow, box, mulga Box-brigalow and/or Brigalow Belah, melanoxylon ironbark, and/or forest woodland belah woodland with low open brigalow, or woodland gum woodland with brigalow, belah, woodland gidgee forest (b) Box, ironbark, mulga or cypress pine (b) Box, forest gum, and/or gidgee on cypress pine understorey mulga, cypress pine gilgaied clays woodland woodland (c) Silver-leaved (c) Box, brigalow, ironbark, mulga gidgee woodland woodland Land units (a) 45, (b) 46, 48,49 (a) 50, (b) 51, (c) 52 53, 54, 55, 56 57 58, 59 (c)47

Fig. 9.—Distribution of land units on depositional plains. 82 R. W. GALLOWAY ET AL.

LAND UNIT 54 (365 KM2)

Field Criteria.—Clay plains, mosaic of gidgee and box or belah, mosaic of gilgaied clays and red earths. Median Rainfall.—Nov.-Apr.: 200-250 mm. May-Oct.: 140-160 mm. Material.—Cainozoic clay. Relief.—Plains with gilgai.

Position on Slope.—Presumably lower slopes. Soil.—Mosaic of gilgaied cracking clay soils and massive earths: Ca (Ug5.24) and massive earths, mainly Ec (Gn2.13, 2.23, 2.83), minor Ea (Gn2.12) in varying proportions; the massive earths are commonly underlain by gravelly layers and calcareous carbonate-enriched clays. Vegetation.—Open-forest, sometimes rather low, of Acacia cambagei, sometimes with occasional or Casuarina cristata; shrub layer, moderately dense and patchy, of and Geijeraparviflora; ground cover sparse, acicularis, Bassia diacantha, Enchylaena tomentosa, gracile, and caroli. Land Capability.—VIc6, g4, S3-4. No. of Observations.—5. 84 R. W. GALLOWAY ET AL.

LAND UNIT 56 (380 KM2)

Field Criteria.—Clay plains, gidgee forest on mosaic of gilgaied clays, texture-contrast soils, and brown soils. Median Rainfall.—Nov.-Apr.: 200-250 mm. May-Oct.: 140-160 mm. Material.—Cainozoic clay. Relief.—Plains with gilgai.

Position on Slope.—Presumably lower slopes. Soil.—Mosaic of gilgaied cracking clay and other soils: Ca (Ug5.24, 5.34), texture-contrast soils, Da (Dbl.23), and/or dark brown and grey-brown soils, Be (Uf6.33, 6.51), in varying proportions. Vegetation.—Open-forest of Acacia cambagei occasionally with some A. harpophylla; shrub layer usually open, Eremophila mitchellii, , Myoporum deserti, and Pimelea pauciflora; ground cover sparse, Tripogon loliiformis, Bassia spp. (B. calcarata, B. diacantha, amd B. lanicuspis). Land Capability.—Vlc6, g4, S3-4. No. of Observations.—4. LAND UNITS, MAPPING UNITS, AND LAND SYSTEMS 85

LAND UNIT 57 (235 KM2)

Field Criteria.—Clay plains, low open woodland of brigalow, cracking clay soils without gilgai. Median Rainfall.—Nov.-Apr.: 200-250 mm. May-Oct: 140-160 mm. Material.—Cainozoic clays and possibly unresistant weathered shales. Relief.—Plains; slopes 0-4-1 %.

Position on Slope.—Presumably on all parts of slope. Soil.—Cracking clay soils; very deep (> 150 cm), self-mulching, strongly alkaline throughout, Cb (Ug5.34); mottled, with gypsum accumulations (10-20%) below 90 cm. Vegetation.—Low open-wood\and of with occasional Eucalyptuspopulnea; ground cover sparse, Solarium esuriale, Atriplex muelleri, Enchylaena tomentosa, Sida trichopoda, Bassia diacantha, and occasional Astrebla spp. Land Capability.—VIc6, S3-4. No. of Observations.—1. LAND UNITS, MAPPING UNITS, AND LAND SYSTEMS 87

LAND UNIT 59 (800 KM2)

Field Criteria.—Clay plains, gidgee forest, gilgai. Median Rainfall.—Nov.-Apr.: 200-300 mm. May-Oct.: 140-190 mm. Material.—Cainozoic clay; possibly some alluvial clay. Relief.—Plains with gilgai.

Position on Slope.—No information. Soil.—Gilgaied cracking clay soils: very deep (>150 cm), self-mulching, neutral reaction in upper 90 cm, slightly acid, mottled, with gypsum accumulations beneath, Ca (Ug5.24). Vegetation.—Open-forest of Acacia cambagei with occasional Casuarina cristata with sparse shrub layer of Eremophila mitchellii and lower Myoporum deserti, ground cover sparse, Chloris acicularis, Enchylaena tomentosa, Paspalidium spp., and Bassia spp. Land Capability.—VIc6, g4, S3-4. No. of Observations.—1. LAND UNITS, MAPPING UNITS, AND LAND SYSTEMS 101

LAND UNIT 73 (280 KM2)

Field Criteria.—Alluvial clay plains, gidgee, cracking clay soils. Median Rainfall.—Nov.-Apr.: 200-300 mm. May-Oct.: 140-190 mm. Material.—Alluvial clay. Relief.—Back plains occasionally flooded; slopes probably 0 • 05-0 • 3 %.

Position on Slope.—No information. Soil.—Cracking clay soils: >120 cm deep, Ce (Ug5.24); a mosaic of cracking and non-cracking clays (Ce/Be) in some occurrences; neutral to mildly alkaline at and near the surface grading to moderately or strongly alkaline beneath where small accumulations of carbonate and gypsum occur. Vegetation.—Open-forest, occasionally woodland of Acacia cambagei, sometimes with occasional Eucalyptus microtheca, E. largiflorens, and Acacia harpophylla; sparse shrubs, mainly Eremophila mitchellii; ground cover low, Astrebla spp., setifolia, and Paspalidium gracile, occasionally replaced by Bassia spp. (B. diacantha, B. convexula, B. tricuspis) and Atriplex lindleyi. Land Capability.—IV-VIC4-6, W3-4, k3-4. No. of Observations.—4.