138 GLACIAL PHENOMENA [Ch. XIL 



To remove from the mind as far as possible this natural feeling of 

 discouragement, I shall endeavor in this chapter to prove that what 

 seems most strikingly anomalous, in the " erratic formation," as some 

 call it, is really the result of that glacial action which has already been 

 alluded to. If so, it was to be expected that so long as the true origin 

 of so singular a deposit remained undiscovered, erroneous theories and 

 terms would be invented in the effort to solve the problem. These 

 inventions would inevitably retard the reception of more correct views 

 which a wider field of observation miffht afterwards suggest. 



o DO 



The term "diluvium" was for a time the popular name of the boul- 

 der formation, because ft was referred by some to the deluge, while 

 others retained the name as expressive of their opinion that a series 

 of diluvial waves raised by hurricanes and storms, or by earthquakes, or 

 by the sudden upheaval of land from the bed of the sea, had swept over 

 the continents, carrying with them vast masses of mud and heavy 

 stones, and forcing these stones over rocky surfaces so as to polish and 

 imprint upon them long furrows and striae. 



But no explanation was offered why such agency should have been 

 developed more energetically in modern times than at former periods of 

 the earth's history, or why it should be displayed in its fullest intensity 

 in northern latitudes ; for it is important to insist on the fact, that the 

 boulder formation is a northern phenomenon. Even the southern ex- 

 tension of the drift, or the large erratics found in the Alps and the 

 surrounding lands, especially their occurrence round the highest parts of 

 the chain, offers such an exception to the general rule as confirms the 

 glacial hypothesis ; for it shows that the transportation of stony frag- 

 ments to great distances, and the striation, polishing, and grooving of 

 solid floors of rock, are here again intimately connected with accumula- 

 tions of perennial snow and ice. 



That there is some intimate connection between a cold or northern 

 climate and the various geological appearances now commonly called 

 glacial, cannot be doubted by any one who has compared the countries 

 bordering the Baltic with those surrounding the Mediterranean. The 

 smoothing and striation of rocks and erratics are traced from the sea- 

 shore to the height of 3000 feet above the level of the Baltic, whereas 

 6uch phenomena are wholly wanting in countries bordering the Mediter- 

 ranean ; and their absence is still more marked in the equatorial parts of 

 Asia, Africa, and America ; but when we cross the southern tropic, and 

 reach Chili and Patagonia, we again encounter the boulder formation, 

 between the latitude 41° S. and Cape Horn, with precisely the same 

 characters which it assumes in Europe. The evidence as to climate 

 derived from the organic remains of the drift is, as we have seen, in 

 perfect harmony with the conclusions above alluded to, the former habits 

 of the species of mollusca being accurately ascertainable, inasmuch as 

 they belong to species still living, and known to have at present a wide 

 range in northern seas. 



But if we are correct in assuming that the northern hemisphere was 



