Mineralogy and Geology. 407 
7. Geological Sketches ; by L. Acasstz. 312 pp., 12mo, with a por- 
trait and woodcuts. Boston, 1866. Ticknor & Fields—This work has 
and admired for the simplicity and beauty of its style, the vividness of its 
descriptions of nature, and the grandeur of its views of the world’s pro- 
ress. Professor Agassiz reviews the prominent events of the successive 
eras in a manner that cannot fail to charm and instruct the most unsci- 
entific reader, and none can rise from the work without appreciating the 
reality of this progress, a d 
neys perforating the Azoic beds, narrow outlets of Plutonic rocks pro- 
truding through the earliest strata,’—while such “chimneys,” or “ fun- 
place in the geological Reports of Canada, or of any other country. — 
Turning to the next chapter, we are told, on page 37, that the Silu- 
vi rgin 
Silurian—a division including, in some regions, thousands of feet of rocks 
representing an era one-third as long as the whole Silurian. 
