are the "ramp" of the eastern plateaux, their uneven but relatively gentle declivity towards the great interior plains. In addition to outliers of the highlands (Mount Exmouth group, Curumbenya Range, etc.) the Cobar (c. 30o miles south-east–north-west; i5o miles wide; altitude 500-1,000 ft.) and Wyalong peneplains—worn-down relics of the buckled ancient floor which protrude through the later surface deposits—are the chief irregularities, though the streams have excavated long and broad transverse furrows.
occupy all the remainder (nearly of the State except the north-west corner where the Barrier "Range" (c. Ioo miles north to south; 3o miles east to west; altitude c. I,000 ft. or 500 ft. above the surrounding plains) forms a series of hard etched and scarped ridges and resembles in struc ture the Cobar "peneplain." The immense plains—substantially the basins of the Upper Darling and a good part of that of the Murray—are floored with recent deposits (probably residuals of an earlier and wetter epoch). The western portions, and the older and higher of these deposits, are prevailingly red and are generally fertile. Black soils are found in the river valleys (e.g., middle Macquarie, Castlereagh, Namoi, etc.) and along the silted-up courses of old streams. The streams, meandering, distributing, and flooding wide over these levels, are continually spreading fresh alluvium. The northern portion (8o,000 sq. miles) reaching south eastwards to Dubbo, falls within the Great Artesian basin, and the south-western parts (Riverina) fall within the Murray-River artesian area. In the former area bores vary from c. 90-4,340 ft. (ay. c. 1,75o ft.), while 38o flowing wells discharge 80,780,000 gals. a day (maximum for single well, 1.5 million gallons).
Of the rivers the coastward-draining are relatively short, the Hunter and Hawkesbury, each c. 34o m. are the longest—rapid and constant-flowing streams, and owing to recent (Pleistocene and earlier) uplift, they are vigorously cutting back and excavating deep canyon-like gorges in the plateaux behind (cf. upper Macleay gorge, 3,00o ft. deep), creating wild and beautiful scenery and opportunities for the development of water-power. The lower basins are undulating to hilly with rich alluvial flats. Sand-barred mouths are common and also lagoon-like lakes (e.g., Lake Mac quarie) due to damming of mouths by marine drift. (Cf. south to
north current along the coast.) Few are navigable for any great distance and then usually for small craft only (e.g., Hawkesbury, 7o miles; Macleay, 39 miles; Shoalhaven, 22 miles). See also RICHMOND RIVER. The inward-flowing streams have been re ferred to. (See AUSTRALIA: Drainage.) Of the Murray, 1,200 miles are within New South Wales. Recent measurements have given the following results: Darling, length 1,16o miles, drainage area 221,700 sq. miles; Murrumbidgee, 981 and 10,700; Lachlan, 922 and 10,420; Macquarie, 590 and 10,090; Namoi, 526 and 9,82o.
Situated wholly in the temperate zone, New South Wales has a generally moderate climate. Average temperatures are higher by 5°-7° F in the north than in the south, and the range increases towards the interior, the mean daily range on the coast being c. 19° F, in the western plains c. 26° F. The transition zone between summer and winter rains passes diagonally (north west to south-east) through the State. The area south-west of the line Broken Hill-Wagga-Albury receives winter rains mainly from Antarctic depressions ("lows") ; the area north-east of a sinuous line running from the north-west corner of the State to New castle receives summer rains from tropical (monsoonal) "lows"; the intervening belt receives rain from both quarters and, in the east, from the passage of anticyclones ("highs") also. The east receives much more rain, and more uniformly, than the interior, the isohyetal lines except in the south and south-west running roughly parallel with the coast. The extremes are in the north east corner (8o in. per ann.) and in the north-west (7 in.). Only 42% of the total area receives an average of over 20 in. per ann.; 15% receives less than 10 in. which is also more or less erratic. Heavy rains cause extensive flooding of the streams resulting often in serious loss; droughts are also a recurrent difficulty, especially in the interior. The rate of evaporation increases from c. 4o in. a year on the coast to c. Ioo in. in the north-west with concomitant seasonal aridity and the drying up of streams. Four main climatic divisions, corresponding to the physiographic, may be distinguished: (i.) Coast: relatively high and regular rainfall coming mainly from the sea, with mild and humid conditions.
Av. ann. temps., in the north 76°-57° F, in the south
F; rainfall 3o-8o in. per ann., greater in the north. (See LISMORE,