NO. 5 PRE-DEVONIAN PALEOZOIC FORMATIONS 265 



(457.2 m.) or more down the north slope, where the strata of both 

 the Devonian and Ozarkian Hmestones are nearly vertical. The upper 

 Ozarkispira fauna of the Mons occurs about 30 feet (9 m.) below 

 the contact, and no traces of the Sarbach formation were seen between 

 the Devonian and the Mons either up the ravine or on the north side 

 of Ranger Canyon opposite the ravine, where there is an outcrop of 

 the Devonian and Ozarkian limestones, but about 2 miles (3.2 km.) 

 to the north on the west side of the northward extension of Ranger 

 Canyon, there is in places a dark arenaceous shale about 6 feet 

 (1.8 km.) thick at the base of the Devonian and below that the 

 siliceous and cherty gray limestones of the Sarbach. I searched in 

 vain for evidence of an unconformity between the Devonian and the 

 Sarbach which here has a thickness of 120 feet (36.6 m.). To the 

 eastward, where the Devonian is again thrust up, there is much more 

 disturbance of the strata and the upper layers of the Mons appear to 

 vary in strike and dip from the Devonian. The upper massive mag- 

 nesian limestones of the Sarbach formation are absent. 



DiSCOMFORMITY 



DEVONIAN 

 CANADIAN 



Sarbach Formation ^ , ,, 



Feet Meters 



\a. Lead-gray, compact limestone in layers 2 to 10 inches 

 (5 to 25.4 cm.) thick with many cherty and magnesian 

 limestone stringers and irregular partings. 



Layers of dark gray, buff-weathering magnesian 

 limestone 3 to 8 inches (7.6 to 20.3 cm.) thick are 

 intercalated at irregular distances from each other 



below 48 feet (14.6 m.) from the top 124 37.8 



From about 30 feet (9.1 m.) to 80 feet (24.3 m.) 

 down, annelid trails nearly cover the surface of the 

 rock and some layers have annelid borings running 

 through them in all directions. These are filled in with 

 siliceous, magnesian limestone that weathers out on the 

 surface in strong relief. 



OZARKIAN 

 MoNS Formation 



\a. Thin layers of gray limestone, with many small irregular 

 concretions containing minute fragments of an Obolus- 

 like shell and bits of trilobite test 236 71.9 



l&. Thick-bedded, rough-weathering, gray limestone inter- 

 bedded with shaly limestones and calcareous shale. 



At 354 feet (107.9 m-) below the summit, thin layers 

 of bluish-gray, shaly limestone occur in bands between 

 the thicker layers. 



