NO. 5 



PRE-DEVONIAN PALEOZOIC FORMATIONS 



Feet 



curs, 3.5 feet (1.06 m.) thick and 4 feet (1.21 m.) 

 below a thicker band of 45 feet (13.7 m.). The gray, 

 light-weathering limestone then continues down with 

 alternating bands of darker magnesian limestone 1,325 



2a. Gray oolitic limestone in layers 3 inches (7.6 cm.) to 

 18 inches (45.7 cm.) thick with partings of calcareous 

 and magnesian limestone shale 145 



Fauna. — (661) and (64r) : The Lyell fauna is still almost 

 entirely undescribed. Among the fossils in it the 

 following genera may be recognized : Lingulepis, Ida- 

 hoia, and forms of Agnostus. Certain cystid plates 

 have proved useful for correlation purposes. 



Total 1,470 



Bos WORTH Formation 



la. Dark bluish-gray compact limestone in layers ranging 

 from I to 10 inches (2.5 to 25.4 cm.) thick with 

 considerable interbedded magnesian buff-weathering 

 limestone in the upper 20 feet (6 m.) 165 



Total Bosworth formation 165 



Arctomys 'Formation 



la. Greenish, very fine argillaceous shale 9 



lb. Steel-gray, hard limestone weathering light gray and 

 buff in bands that break down on weathering into 



shaly and thin layers 44 



20. Alternating bands of purple and gray-colored arenaceous 

 shale and thin layers of purplish red sandstone, the 

 surfaces of which are usually ripple marked and 

 checked by sun cracks that were filled in by fine sand 

 and silt. A few small annelid trails occur on the shaly 

 sandstone but no other traces of life were observed. . . 42 



The ripple marks and the sun and wind dried, 

 cracked surface all indicate a shallow sea, the bottom 

 of which was exposed to the air between tides. 



267 

 Meters 



4039 

 44.2 



448.1 



50.3 

 50.3 



2.7 

 134 



Total Arctomys formation. 



95 



12.8 



28.9 



MIDDLE CAMBRIAN 



Eldon Formation 



la. Thin-bedded, steel-gray magnesian limestone, weathering 

 dove-gray. No traces of life seen in or on the layers. 

 Estimated 300 -f 



91.4 + 



