THE BEACON SANDSTONE AT INLAND FORTS. 
43 
Groin respectively, are low and attenuated spurs of the horizontally bedded 
sandstone, which is here cut into cirques. The groins afford the most easily 
accessible exposures of sandstone in the whole region. The slope was seldom 
too steep to be climbed, and, as the horizontal structure is well etched out by 
denudation, any particular bed may be traced along the whole length of the 
ridge. Here, too, the rock was a white or yellowish sandstone with not so 
much as a sign of a shale or a limestone-band. So far as could be ascertained, 
only one of its horizons contained organic remains, and these of a most doubtful 
nature. These were found on West Groin, where the surface of a sandstone-bed 
was covered by what appeared to be cylindrical casts of 
some organism (763-767). Possibly these cylinders may 
be entirely a result of weathering, but, as they are all of 
much the same diameter and cross and intercross in all 
directions, I thought at the time that they are probably 
more than this, and I still think that they may be of organic 
origin. There is no sign of actual structure in the bound- 
aries of the cylinders, but there is usually a slight depression 
parallel to, and close along, their sides. The length of the 
cylinders varies from six inches to three feet, and the 
diameter is usually about half an inch ; they project nearly 
half an inch above the smooth surface of the surrounding 
sandstone. 
At another spot on West Groin, 800 feet above the 
level of the ice, there occurred an impression (763, 764) on 
the surface of the sandstone. This appeared as a shallow 
hollow, somewhat like the imprint of a flat crooked stick 
with a blunt rounded end (Pig. 21). The impression was an 
eighth of an inch deep, two inches wide, and one and a 
half feet long. 
O 
Along the central line there are two markings „ _ 
o o of Sketch made in the Field. 
parallel to the outer boundary and about a quarter of an 
inch apart. These run nearly the whole length of the impression, and on either 
side of them are rows of rather deeper pits about a quarter of an inch apart, 
which alternate on the two sides of the central lines (see note by Mr. E. A. Newell 
Arber, on p. 48). 
Sundry other, but smaller, rod-like markings (765-769) occur on other specimens, 
and with the same alternate pits, and I am inclined to think that these impressions 
are, at least remotely, derived from bodies with organic structure. One of the smaller 
impressions, which are 6 inches to 1 foot long and about half an inch across, still 
retains fragmentary remains of dark carbonaceous matter. The following table of the 
succession, from the bottom of West Groin to the top of its corresponding hill, shows 
how uniform is the Beacon Sandstone Formation. 
G 
9 
