40 FIELD MUSEUM OF NATURAL HISTORY 
another part shows geological structure as well as topography. 
To some extent the topography is shown on one map and the 
geological structure on another, so that both elements are repre- 
sented with the greatest distinctness. The portions of the sur- 
face selected to be represented are usually such as to portray 
some typical form of surface sculpturing or of volcanic accumu- 
lation. Some, however, represent natural or political divisions. 
In addition to the relief maps, there are models showing 
geological structure or illustrating methods of development. 
Some of these are dissected so as to show the more intimate 
structure of the formations. There are also exhibited globes, 
wall maps, and other geographic material. The following is a list 
of the principal features: 
Hall 76. 
Entering this hall from the West Dome and passing around 
to the right, the maps against the wall will be found in the 
following order: 
Relief map of Kentucky showing topographical and geologi- 
cal features and location of principal coal fields. 
Relief map of the United States showing limits and theoreti- 
cal curvature of the ancient ice sheet at the stage of the Glacial 
period following the main epoch. Modelled on a section of a 
globe i6^ feet in diameter. Scale, i inch equals 40 miles. 
Relief map of Missouri showing topographical and geological 
features and principal mining districts. 
Relief map of New Jersey showing topographical and geo- 
logical features. 
Model of Henry mountains and vicinity, Utah, showing geo- 
logical formations and effects of erosion. 
Geological and relief map of the Henry mountains showing 
effects of erosion. 
This is on a larger scale than the preceding map and shows 
only a portion of the same territory. 
Same as the above, ideally restored before erosion took 
place. 
Model showing Henry mountains and vicinity ideally re- 
stored before erosion took place. 
This is on the same scale as the first of the series. 
The foregoing series of four maps illustrates the formation 
of laccoliths or dome-like mountains produced by the intrusion 
of lava. 
