too THE POPULAR SCIENCE MONTHLY. 



the bottom along certain lines, and the Antarctic Continent, other- 

 wise almost unknown, makes its presence felt to the di-edge by the 

 abundant masses of crystalline rock, drifted far from it to the north. 



These are not altogether new discoveries. I had inferred many- 

 years ago, from stones taken up by the hooks of fishermen on the 

 banks of Newfoundland, that rocky material from the north is dropped 

 on these banks by the heavy ice which drifts over them every spring, 

 that these stones are glaciated, and that after they fall to the bottom 

 sand is drifted over them with sufficient velocity to polish the stones 

 and to erode the shelly coverings of Arctic animals attached to them. 

 If, then, the Atlantic basin were upheaved into land, we should see 

 beds of sand, gravel, and bowlders with clay flats and layers of marl 

 and limestone. According to the Challenger reports, in the Antarctic 

 seas south of 64°, there is blue mud with fragments of rock in depths 

 of twelve hundred to two thousand fathoms. The stones, some of 

 them glaciated, were granite, diorite, amphibolite, mica-schist, gneiss, 

 and quartzite. This deposit ceases and gives place to Globigerina 

 ooze and red clay at 46° and 47° south ; but even farther north there 

 is sometimes as much as forty-nine per cent of crystalline sand. In 

 the Labrador current a block of syenite weighing four hundred and 

 ninety pounds was taken up from thirteen hundred and forty fathoms, 

 and in the Arctic current, one hundred miles from land, was a stony 

 deposit, some stones being glaciated. Among these were smoky 

 quartz, quartzite, limestone, dolomite, mica-schist, and serpentine ; 

 also particles of monoclinic and triclinic feldspar, hornblende, augite, 

 magnetite, mica, and glauconite — -the latter, no doubt, formed in the 

 sea-bottom, the others drifted from Eozoic and Palaeozoic formations 

 to the north. 



A remarkable fact in this connection is that the great depths of the 

 sea are as impassable to the majority of marine animals as the land it- 

 self. According to Murray, while twelve of the Challenger's dredgings 

 taken in depths greater than two thousand fathoms gave ninety-two spe- 

 cies, mostly new to science, a similar number of dredgings in shallower 

 water near the land gave no less than one thousand species. Hence 

 arises another apparent paradox relating to the distribution of organic 

 beings. While at first sight it might seem that the chances of wide 

 distribution are exceptionally great for marine species, this is not so. 

 Except in the case of those which enjoy a period of free locomotion 

 when young, or are floating and pelagic, the deep ocean sets bounds 

 to their migrations. On the other hand, the spores of cryptogamic 

 plants may be carried for vast distances by the wind, and the growth 

 of volcanic islands may effect connections which, though only tem- 

 porary, may afford opportunity for land animals and plants to pass 

 <»\cr. 



With reference \<> the transmission of living beings across the At- 

 lantic, we have before us the remarkable fact that from the Cambrian 



