Williams.] THE GRAPTOLITE SHALES OF CHAPMAN. 4 5 
be adopted, the terrane may be regarded as older than the Sheridan 
sandstone and Ashland shale and limestone, and as representing" the 
base of the Silurian for this region. 
There is little doubt as to its being more recent than the pure, non- 
calcareous slates, a considerable belt of which cuts across the country 
in a southwesterly direction west of the Aroostook limestone. 
GRAPTOLITE SHALES. 
In the northern part of Chapman Township Dr. Gregory discovered, 
in 1898, a calcareous sandy shale containing graptolites. The section 
(1099 D) 1 is on the sides of a hill in the western part of Chapman, on 
W. H. Littlefield's farm, on the west side of the Swanback road, and 
about three-fourths mile south of the Mapleton line. 
The strata present two planes of fissility, as is frequently the case 
with the shales of all this region. Judging, however, from the plane 
in which the graptolites lie in the rock, the strike of bedding is about 
N. 35° E., with a dip of about 60° NW. The other plane of fissility 
has a strike of about N. 70° W. , and dips at an angle of 25° SE. With 
this interpretation of the position of the strata, 1099 D 5 on the west 
side of the hill would be the highest stratum; then D 1, which may be 
a continuation of D 5, and below this D 2 and then D 3. 1099 D 3 is a 
fine-grained brown-gray sandstone, with nodules or lenticles of argil- 
laceous limestone, which are believed to be the Aroostook limestone. 
This weathers by leaching to a rottenstone, in which condition no bed- 
ding is evident. In D 3 graptolites are rare, but Coleolus is frequent. 
Above D 3, 150 feet or so, the shales, D 2, are dark gray and little 
calcareous, or not at all so, and glisten with mica grains on the fractures, 
the rock splitting along what are believed to be the bedding planes, on 
which lie the fossil graptolites. 
Above D 2 is D 1, more purely arenaceous than D 2, and fine grained. 
This stratum contains only occasional crinoid stems and fragments of 
corals or some other calcareous fossil. 
On the opposite or west side of the hill, still dipping westward, is 
D 5, which closely resembles D 1, and which contains crinoid stems and 
traces of Coleolus. The immediate relation to other rocks is not evi- 
dent, but about a quarter mile to the north of D 3, on lot 9 of Chapman 
Township, occurs a limestone striking N. 30° E. and standing nearly 
vertical. At that exposure the limestone abuts against a sandstone 
similar to the one farther south, and it is probable that the sandstones 
are stratigraphically older than the limestone. The fossils of this lime- 
stone enable us clearly to identify its age as Eosilurian. The fauna i.s 
that of the Ashland limestone. 
1 The numbers here and below refer to the rock exposures, the locations of which are given in Pt. 
Ill of this bulletin. 
