CAKBONIFEKOUS SYSTEM. 251 



In the "preceding pages, a general southwesterly dip of the 

 strata of the State has been often referred to; by which it is 

 meant that all the formations are seen to disappear "beneath 

 each other as one goes in any direction, between west and 

 south, from the eastern part of the State. This will be more 

 clearly understood by referring to the geological map-model 

 in the first part of this volume. The true line of general dip 

 is usually assumed to be at right angles with the trend or 

 border of the formation, but this is at best only approxi- 

 mately correct. In the case of the Iowa strata, the true line 

 of general dip is much more nearly to the southward than is 

 indicated, by the trend of the borders of the respective forma- 

 tions, as represented upon the geological map and the 

 map-model. This arises from the fact that the southward 

 slope of the surface of the State is in the same direction that 

 the dip of the strata is there, while the eastward slope of the 

 surface of the State is in a contrary direction from the dip of 

 the same; namely, to the westward, as well as southward. 

 All the formations thus far described, except the last, pass 

 beneath each other to the southward by an actual dip, which 

 is greater than the southerly slope of the surface, while to the 

 westward their disappearance is partly due to an actual dip 

 in that direction it is true, but also largely due to their 

 passing beneath others that occupy levels which are in some 

 cases successively almost as much higher than the preceding 

 one, as the amount of its vertical thickness. 



Thus the westerly dip of the strata is more apparent than 

 real, or at least it is actually less than it appears to be, if 

 we lose sight of the fact that there is a westerly rise of the 

 surface from the Mississippi river to the Great Watershed. 

 A profile of the Burlington and Missouri river railroad, 

 kindly furnished by its Chief Engineer, Mr. H. Thielsen, 

 shows that Highland station, the highest point between the 

 two great rivers, is nearly eight hundred feet above low 

 water in the Mississippi river at Burlington, and nearly 

 four hundred feet above low water in the Missouri river at 

 Plattsmouth. This high point is in Union county and upon 



