A black carbonaceous highly graptoliferous phyllite. Tectonically shredded, silty varieties near and on Whipstock Hill constitute the Whipstock Breccia Member of Potter (1972) (Oww). Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).
On the original printed map, there are 2 unit descriptions for Owbl. Chose to change label to Owbl2 and change in GIS. Unit description refers to rocks not on Whipstock Hill. Other unit description for Owbl refers to rocks on and west of Whipstock Hill.