4 Dansk Botanisk Arkiv, Bd. 2. Nr. 8. 



the mountains reach the coast in many places. In other places 

 a low foreland is present, as is also the case in the intermediate 

 district, especially "the Ninety Mile Beach" from Port Hedland 

 to Broome. This foreland is sandy and covered by dunes; in 

 bays and outlets of the rivers the mangrove sets in. 



The climate 1 is tropical and dry. The average temperature 

 for Broome (Lat. 18 ° S.) is 26 ° 6 C, the hottest months being 

 December and January with an average of 29 ° 9 C, and the 

 coldest June— July with 21 ° 7—21 ° 8 C. (see Fig. 2). But the 

 maximum temperatures rise much higher, and their effects upon 

 the vegetation must be very pronounced. We learn that a tem- 

 perature of 49 ° G is not very rare in the interior, and 38 ° C not 

 rare at the coast. Especially significant is the fact that periods 

 of uninterrupted high temperature sometimes occur. E. g. the 

 temperature did not sink under 37 ° 8 (100° F.) in 64 consecutive 

 days in 1902 at Marble Bar, nor in 57 days in 1900 at Nullagine, 

 two places in the interior of the north-western district. No doubt 

 such prolonged heat spells must have a very disastrous result as 

 regards the plant world, at least when not accompanied by rain. 



And rain, the second important climatic factor, is scanty. 

 The rainfall increases from the north-western corner towards north- 

 east (see Fig. 1), but in no district does it reach such a degree 

 that a rich tropical vegetation can thrive. The north-western 

 district is in reality a desert, the average annual rainfall not 

 reaching c. 500 mm (20 inches) in any place, while the best part, 

 the northern Kimberley, has a rainfall between 750 and 1000 mm 

 (30 — 40 inches); Broome, the best meteorological station, at the 

 south western corner of Kimberley has 583 mm (22.96 inches). 

 There is thus a considerable difference in this respect between 

 the north-west and the Kimberley districts, and what makes this 

 difference even more perceptible than the figures show, is the 

 regularity of the rainfall in the Kimberley district and the ir- 

 regularity in the north-western district. In the latter, the rain- 

 fall differs greatly from year to year. The rain here comes usu- 

 ally with the hurricanes, which sweep over the country during 

 the summer, but are very capricious in their occurrence. During 

 year-long periods hardly any rain falls, and then a hurricane brings 



1 See: Hunt, H. A.: Climate of Australia, in Federal Handbook of 

 Australia, prepared in connection with the 84th meeting of the Bri- 

 tish Association for the Advancement of Science held in Australia 

 August 1914. Melbourne 1914. See also: W. A. Year-Book for 1900 

 —1901, vol. I, Perth 1902, pp. 135—157. 



