Cockayne. — Plant Geograpliy of the Waimakariri. 129 



concerned, or a difference of 14:'6° between the middle of the 

 Trelissick basin (609 m.) and the summit of Mount Enys 

 (2,134 m.). This excess of cold is met by the protecting 

 action of the snowy mantle which covers all the alpine 

 region except certain precipitous rocks near the very summits. 

 Even these unprotected spots have their phanerogamic vege- 

 tation* ; on one such in the Craigieburn Mountains, at an 

 altitude of 1,980 m., I have noted Cardaminc cnysii and Ve- 

 ronica epacridea growing in profusion, in places during January 

 the rocks being white with blossoms of the former. Summer 

 snow-storms are frequent, especially during south-west wind, 

 but sometimes also coming from the north-west. The rainfall 

 varies according to position with regard to north-west rain ; 

 thus it is certainly greater on the summit of the Craigieburn 

 INIountains than on Mount Torlesse. This heavier rainfall 

 and greater frequency of rainy days has caused in favourably 

 situated stations a richness of vegetation approximating to 

 the western region, and even some of the western plants 

 make their appearance — Senecio scorzonerioides, e.g. The sky 

 is frequently cloudless, and insolation stronger than in any 

 other region. There is no comparison at times between this 

 direct action of the sun and the temperature of the air. 

 It may be most delightfully warm on one side of a gully, 

 sitting in the sunshine, and on the other, at hardly the dis- 

 tance of two metres away, bitterly cold, ground and plants 

 being frozen hard. Temperatures such as these have been 

 measured in various parts of the world. Hookerf writes, 

 "This effect (solar radiation) is much increased with the ele- 

 vation; at 10,000 ft., in December, at 9 a.m., I saw the 

 mercury mount to 132° with a difference of + 94°, while the 

 temperature of shaded snow hard by was 22°." The moisture 

 in the atmosphere at times when the mountains are clothed 

 with cloud and mist must be very considerable. On the other 

 hand, during the clear weather the rarified atmosphere must 

 be very dry. It is a beautiful and interesting sight from an 

 elevation of 1,200 m. on Mount Torlesse, the sky overhead 

 clear, to look down upon a great level stretch of white dense 

 cloud marking the Canterbury Plain. The soil and subsoil 

 ai'e much the same as in the subalpine region, but streams 

 are less frequent, and towards the summits altogether want- 

 ing. Moist ground with permanent lagoons sometimes occuis. 

 Many of the slopes consist of shingle-slips, sometimes made 



* Similar examples are given by Christ {loc. cit., p. 295) from Swit- 

 zerland, where on the Col de St. Theodule, which has an average tem- 

 perature for the year of — 5-59° C, a minimum of — 21-4° C, and a 

 maximum of 15 1° C, with an altitude of 3,333 m. above the sea, thirteen 

 species of flowering-plants grow. 



t Himalayan Journals, vol. ii., London, 1854, p. 410. 



9 



