
good preservation & mixed with fragments of vegetable matter much of it carbonized & some silicified.
The matrix was a sand rock sometimes argillaceous enough to approach shale in character.
Sanborn Harbor. Nagai Id. 
Aug. 1872
The geological characters of the middle portion of this island are as follows.
The strata at the surface are metamorphic sandstones & slates generally dipping to the westward but arranged in waves having their longer axis about NNE & SSW. sometimes faulty but in general pretty regular and occasionally an exposure perpendicular to the axis shows the wave complete & unbroken. The slates & sandst.