A GEOLOGICAL LESSON, 67S 
at diiferent heights as the high water gradually receded, which he saw when on a 
visit to his grandfather in Vermont. 
Now such familiar facts as these, which are fair representatives of what may 
be found in an hour's walk in almost any country place, may easily be made the 
basis of a large amount of geological knowledge which will be a real acquisition, 
and not the utterly hypothetical and intangible stuff as a substitute for knowledge, 
which one gets from mere text-book perusal. When the student, whether young 
or old, has once grasped the idea, from actual observation, that the hills and valleys 
in our surface soil are caused by the erosive power of water, he is, for the first 
time, ready to comprehend the broader facts of mountain sculpture, canon 
erosion, and denudation, which have wrought such stupendous changes upon 
the surface of our globe. 
From the simple discovery of a bone or shells in the soil, or a buried brick- 
yard, the thoughts natually expand to the closely related facts of the origin of 
fossiliferous beds; the mode of deposition of stratified and sedimentary rocks, 
varying in aggregate thickness over the earth's surface from a few inches to fif- 
teen or twenty miles; and the order of succession of geologic events. And 
these embrace the whole of historical geology, and part of dynamical and litho- 
logical geology. 
Again, the observation of rounded boulders in every creek-bed and often in 
higher positions; of the foreign or "lost rocks" often seen even in elevated 
fields ; and of the thick and wide-spread deposits of the sandy loess in northern 
latitudes, which are just like the silty mud left high and deep nowadays after the 
flood waters of the muddy Missouri have subsided, forces unbidden upon the 
thinking mind a consideration of the unmeasured caps of moving ice progressing 
southward like an immense plow ; the subsequent floods, perhaps more universal 
than Noah's, transporting and assorting unnumbered tons of material with over- 
whelming power; and the vast lakes of muddy water which succeeded. 
Till the method of studying the earth's history, — not only by geologists, but 
by teachers and pupils in school, — proceeds from the known to the unknown, 
and the facts under our daily observation are made the starting point in explain- 
ing those of like character which occurred in ages past, we need not be surprised 
that students graduate with no practical knowledge of geology, for the lack of 
which their future fortunes are often destroyed ; that good but simple men fear a 
knowledge of the works of God will weaken faith in his word and himself; or 
even at the inglorious boast of a " thorough " educator that he has "yet to learn 
any practical use for geology," and frequent ridiculous guesses in attempted ex- 
planation of scientific allusions in the Bible record. 
