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CHARLES BUTTS 



ing into regular prismatic blocks of very characteristic appearance. 

 The bottom of the formation has not been definitely determined in 

 the region; the top is well marked by the Genesee shale, and has 

 been located within narrow limits from the vicinity of Bellwood, on 

 the Pennsylvania Railroad, 6 miles northeast of Altoona, to Queen, 

 about 20 miles southwest of Altoona. In a railroad cut at a point 

 I mile southwest of Bellwood, where the present main tracks of the 



Fig. 4 



Pennsylvania Railroad diverge from the old tracks, the contact 

 between the Hamilton and Genesee is well exposed. The topmost 

 layer of the Hamilton is an impure limestone, 2 to 4 feet thick, crowded 

 with Hamilton fossils, and immediately overlying it is the character- 

 istic black Genesee shale. At Altoona the contact is not exposed, 

 but its position can be closely determined. On the Pennsylvania 

 Railroad track, beginning about 2,375 ^^^t west of the Logan Hotel 

 and just west of the underground crossing of the electric road to 

 Hollidaysburg, is an exposure extending along the track westward 

 for 540 feet, as shown in Fig. 2, Hamilton fossils were found in 



