360 The Upper Devonian Deposits of Maryland 



Orleans. The lower rocks are olive shales interstratified with some 

 rather massive greenish-gray sandstone. The higher rocks contain some 

 fossils as Amhocoelia umbonaia (Conrad), and Atnjpa reticularis 

 (Linne). The rocks at this fossiliferous horizon are largely argillaceous 

 shales which weather to an olive or biiff color. Toward the top of the hill 

 in the shales and some slightly coarser layers are fossils though at no place 

 are they abundant. 



Exposure on Green Ridge. — This section follows the National Road 

 along which there are fair outcrops up the western slope of Green Ridge. 

 The base of the section begins near the lower part of the hill to the east of 

 Fifteen Mile Creek. 



No. 1. Tlie lowest rocks are olive to biifP, smooth, argillaceous shales 

 with layers of greenish-gray sandstone not more than 6 to 8 inches in 

 tliickness. These shales and sandstones belong in the Woodmont member 

 of the Jennings formation. Higher is the first zone of fossils near the top 

 of one of the thicker layers in which are specimens of Camarotoechia sp., 

 but the fossils are fragmentary. At this part of the section the lithologic 

 characters remain about the same as in the lower exposure. 



jS'o. 2. Lithological appearance of the rocks about the same as in 

 No. 1 but no fossils wore found. 



No. 3. A zone of somewhat crumbly and mealy shales in layers of 

 which there are numerous specimens of Camarotoechia sp., with a few of 

 Spirifer mesacostalis Hall. This zone is about 5 feet in thickness. 



No. Jf. Olive shales interbedded with thin sandstone ; fossils rare. 

 This zone extends up to the base of the lowest brownish shales. 



No. 5. At the base of this zone are brownish argillaceous shales but 

 most of the rocks are olive to buff shales alternating with thin sandstone. 

 No fossils were found in this zone, which occurs on the highway below the 

 farm house. From the top of this zone for some distance the rocks are 

 concealed (No. 6). 



No. 7. The rocks of this zone are composed of shales and thin sand- 

 stone to arenaceous, coarse, blocky shales. They weather to a brownish 

 or buff color with j)atches and streaks of rather bright red due to weather- 

 in? of the iron contained in the rock. The base of this zone begins 

 a ehort distance above the farm house and in a thin sandstone layer are 



