PORTION OF THE SCHUYLKILL COAL-FIELD. 87 



of relative heights and lengths are thus so grossly caricatured, 

 that they bear but distant resemblances to what is intended to 

 be represented. The inclinations of strata are changed from 

 moderate angles almost up to vertical ; the altitudes of hiUs are 

 stretched to the eminence of lofty peaks ; rounded secondary 

 mountains assume the form of attenuated spkes ; gentle undula- 

 tions become craggy steeps, and the ordinary surface of a country 

 is thus metamorphosed into a region harshly broken into pinna- 

 cled spires and Alpine crests, and steep and fathomless gulfs — a 

 hideous burlesque upon the actual aspect of the district represen- 

 ted, or rather misrepresented. 



In constructing geological diagrams I have, for some time, 

 ceased to make any difference between the horizontal and verti- 

 cal scales. At any rate I have endeavored, as closely as may 

 be, to adhere to that principle. If the drawings be executed with 

 delicacy they rarely require a deviation from the rule ; and I 

 would respectfully recommend an adherence to it, among my 

 geological friends, particularly in relation to the State surveys, 

 where comparisons of sections are continually needed. We 

 shall then, and not tiU then^possess something like uniformity in 

 the representations of similar things. So long as the distorting 

 principle is tolerated, we shall continue to convey and to view 

 every thing under a false medium, and shall describe objects 

 under every shape but their real one. Geological sections, if 

 draAvn with suitable care, and with the nicety that such works 

 demand, particularly if they be engraved rather than lithographed, 

 may be made perfectly distinct at a very small vertical scale. 

 Detailed sections of particular portions, on a larger scale, can 

 readily accompany and elucidate the general section. The pres- 

 ent writer has constructed sections of many hundred miles in this 

 country upon a scale, both vertical and horizontal, or very nearly 

 con-esponding, as small as five miles to an inch, and yet has ex- 

 hibited all important features therein. The system is clearly the 

 right one, and ought to be followed. It is the only one, in fact, 

 which can be made to exhibit the true inchnation of tlie sti-ata, 

 the real bearing, position and magnitude of the formations and 

 their relation to each other, and furnishes the means of measuring 



