336 ANNUAL, REPORT SMITHSONIAN INSTITUTION, 1920. 



from 50 to 100 feet of profusely fossiliferous Franconia. Incident- 

 ally the presence of the fault just mentioned was unquestionably es- 

 tablished. As an interesting and welcome confirmation of the earlier 

 conviction that the Franconia is older than the Mazomanie — wel- 

 come despite the fact that it came to light after the case had been 

 proved by actual superposition — I may add that two entirely new 

 faunas, one from near the top, the other just above the base of the 

 formation, were discovered in the Mazomanie. The upper of the 

 two occurs rather widely distributed but in a sandstone so friable 

 that it can not be picked up without crumbling in one's hand. De- 

 spite this difficulty a considerable collection was made and safely 

 transported to Washington by soaking the sand with shellac. 



I have described the solution of this problem in greater detail than 

 may seem necessary, first because of its intrinsic value and interest 

 as a new instance of oppositely overlapping formations, second be- 

 cause of its bearing on the question of differential surface move- 

 ments, and third as an illustration of the thoroughness of modern 

 stratigraphic investigations. 



The case shows differential movement, first in the fact that the 

 Franconia is confined to the western half of the State, whereas the 

 preceding Dresbach was laid down on the east side and over the 

 south side as well as the west. Next, the very different distribution 

 of the Mazomanie shows reversal of the tilt from the west toward 

 the east. Further — through the fact that the two formations are sep- 

 arated to the south of the Baraboo Range by a broad strip, in which 

 neither is present, whereas to the north of the pre-Cambrian range 

 both formations were laid down so that the younger overlaps the 

 older for a distance of at least 50 miles — it is proved that the move- 

 ment was not simply an east- west reversal of tilt but that it was 

 accompanied by additional local subsidence on the north where a de- 

 pression was formed that subsequently lodged a considerable embay- 

 ment of the Mazomanie sea. 



But this does not exhaust the known record of diastrophic move- 

 ments of this time in Wisconsin. Uplifts of the relatively evenly 

 distributed floor of Dresbach sandstone are indicated in many places ; 

 and depressions occurred in other localities so that the Franconia 

 lapped over in such places onto the pre-Cambrian rocks. This occurs 

 at Taylors Falls, and possibly at Berlin, 6 towns located on opposite 

 sides of the area covered by the formation. At Osceola, on the other 

 hand, there is a narrow ridge on the surface of the Dresbach that 

 completely cuts out the Franconia, though the formation is well de- 

 veloped both to the north and south of Osceola. Finally, we recog- 



9 Larger collections and a more thorough study of the fossils found in the Cambrian 

 sandstone that lies on the uneven pre-Cambrian floor at Berlin, Wisconsin, tend to the 

 conclusion that this bed is of Mazomanie or possibly even of St. Lawrence age, hence 

 younger than the Franconia. — E. O. Ulrich, Mar. 18, 1921. 



