576 Dr. Bicketts — On the Cause of the Glacial Period. 



Changes of climate are now taking place for which I can imagine 

 no adequate cause, excepting the reckless destruction of the great 

 American forests. The temperature of Iceland and of Greenland 

 is much more rigorous than when they were first discovered; 1 

 whilst, upon the other hand, the glaciers of Norway are receding, 

 and the Christmas of tradition visits us at very distant intervals. 

 Even temporary changes as indicated in North America appear 

 to influence our winters ; thus of late years the most severe winters 

 there, such as those of 1872-73 and 1873-74, were with us re- 

 markable for their mildness. The opposite conditions have also 

 been noticed; such as occurred during the Kussian War in 1854-55, 

 when the frost on the Eastern shores of the Atlantic was intense, 

 whilst the winter was mild in Northern America. It has been stated 

 that "it is a saying amongst the Danes that there is mild weather 

 in Iceland when it is cold in Europe, and vice versa." 2 



Previous to the Glacial Period there existed a very different contour 

 of the North American continent from the present. The Gulf of 

 Mexico extended over what is now the valley of the Mississippi, even 

 to St. Louis, upwards of 600 miles north of New Orleans ; the 

 peninsula of Florida was submerged ; and along the east coast a 

 very considerable belt of land, extending to the Alleghany Mountains, 

 was sunk below the level of a sea whose waters were of a tropical 

 temperature. Such a variation in the coast-line must have had a 

 great effect upon the climate. With a Gulf of Mexico extending 9° 

 farther north than it does at present, the air, heated and charged 

 with moisture derived from its tropical waters, would have been 

 directed up the valley of the Ohio by the western flanks of the 

 Appalachian chain, and have modified the climate even of extreme 

 northern districts. Florida presenting no obstruction, the Gulf 

 Stream must have been impelled many degrees further northwards 

 by the vis a tergo — the N.E. and S.E. trade-winds — carrying a larger 

 quantity of Equatorial water than it now conveys, namely, that 

 which is deflected round the western extremity of Cuba and what 

 escapes over the Bahama banks and channels. Therefore the 

 amount of heat derived from the tropics which was conveyed to 

 high northern latitudes must have been immensely increased. I 

 am not aware whether it is possible to co-ordinate those beds abound- 

 ing in plant-remains, which have been discovered in Greenland, in 

 Iceland, and in Spitzbergen, with those indicating these changes in 

 the coast-line of America ; but such alterations must have induced a 

 condition of temperature at all events nearly approaching, if not 

 similar to, that which these plant-remains indicate. 



As the present state of the winter temperature of Britain depends 

 on the volume and warmth of the North Polar Current, the waters 

 of which are, to a considerable extent, derived from those of the 

 Gulf Stream, it follows that any serious diversion of this stream 

 would affect our climate in an opposite direction. 



There are two areas in the isthmus which separates the Atlantic 



1 A Visit to Iceland. By Madame Ida Pfeiffer. Page 64. 



2 Iceland: its Scenes and Sagas. By S. Baring-Gould. Page xrsi. 



