UNCONFORMITY AT BASE OF ONONDAGA LIMESTONE 315 
The character of the disconformity between 1 and 2 is shown in 
the accompanying photograph (Fig. 6). The bed on which the 
hammer rests is No. 2 of the above section. This disconformity 
is also seen in the William Avery quarry on the east side of Conn’s 
Fic. 6.—The disconformity between the Devonian and Silurian limestones on 
Flatrock Creek, Shelby Co., Ind. The hammer rests upon the top of the Silurian 
limestone. 
Creek about 1 mile below Waldron, where it is marked by a band 
of residuary clay in the following section: 
CONN’S CREEK SECTION 
ta Ft. In, 
i. Brownish-bufi sandy-looking limestone..............0..6: cs .000- 2 6 
2, (CORRS? eae ake Tee UR er er ae re a I 
prebine hinestone mn3= to 6-In. layers... 2... <5 ones ec eee vo tile ele nee 5 96 
Between the area in the Ohio valley in which outcrops of the 
Devonian limestone are abundant, and the Wabash valley, where 
they are also common in a limited district, an extensive drift- 
covered plain intervenes in which but two or three outcrops of 
Devonian rocks are known. 
