Schaw. — On the Last Glacial Epoch. 517 



we find in the best physical atlas that the mean temperature 

 in the depth of winter in the Northern Hemisphere varies in 

 different places between —4° and +41°, while in the Southern 

 Hemisphere it is about +45°. In the height of summer 

 in the Northern Hemisphere in this latitude the tempera- 

 ture varies in different places between 54° and 77°, while 

 in the Southern Hemisphere it varies very little from 59°; 

 or, if we take the mean for the year, in the same latitude 

 north it is 52°, and south it is 55°. As we might expect, in 

 the Northern Hemisphere, with its great continents, the range 

 of temperature is very great ; while in the Southern Hemi- 

 sphere, with but little land and vast stretches of ocean, the 

 temperature is more equable, but at the same time it is some- 

 what higher on the average, and this notwithstanding the 

 present position of the equinoctial line in the earth's orbit, 

 which causes the summer to be shorter and the winter longer 

 in the Southern Hemisphere than in the Northern by a few 

 days. 



The effect of cold and warm ocean-currents is well ex- 

 emplified in the Northern Hemisphere by the line indicating 

 the extreme north limit where cereals will ripen. On the east 

 coast of North America, chilled by the arctic current, the limit 

 is lat. 48° N. ; while in north-west Europe, w T armed by the 

 Gulf Stream, the limit extends to the North Cape in lat. 72° N. 

 On the w r est coast of North America, which is not chilled by 

 an arctic current as the current flows into Behring Straits, 

 the limit of cereals is about 58° 30'. We have no land in 

 similar positions in the Southern Hemisphere to compare with 

 these except in New Zealand; Stewart Island, lat. 47° S.; and 

 Tierra del Fuego, lat. 53° S. 



As regards the geological record of glacial action on an 

 extended scale in New Zealand in geologically recent times, 

 it is plain and abundant in the Provinces of Otago and Can- 

 terbury, and, as I am informed by Mr. McKay, as far 

 north as the Grey Eiver Valley on the West Coast in about 

 lat. 42° 30'. As to the limits of glacial action on the east 

 coast of the Middle Island, and on the question of any means 

 we may have of judging either the duration or the date of the 

 termination of this epoch in New Zealand, I will say nothing; 

 but I hope we may have some valuable information on these 

 points from Sir James Hector, Mr. McKay, and others who 

 are experts in the geology of New Zealand. 



It has occurred to me, however, as being highly probable 

 that the peculiar surface-carving of the clay hills around 

 Wellington may be traced to the climatic conditions of the 

 Glacial period, when there must have been very severe winter 

 frosts here, with heavy snowball, and very hot summers, 

 producing rapid thawing and violent torrents of water stream- 



