140 CONTRIBUTIONS TO THE GEOLOGY OF MAINE. [bull. 165. 
As shown by the table on page 119, limestone will include those cal- 
careous rocks with considerable quartz, those with very little quartz, 
and those of calcite alone, and they will be described as arenaceous 
limestone, slated limestone, and white f ossilif erous limestone. 
ARENACEOUS LIMESTONES. 
Rocks of this class occur as thin beds among the more calcareous 
members of the Aroostook limestone series, or as wide beds forming 
hills of considerable size. A good example is found in the railroad 
cut half a mile south of Presque Isle Station, and also in the road near 
the Academy Building, where the rock has the appearance of a quartz- 
ite sandstone interbedded with limy slates. It is cleaved and sheared, 
and has the recemented cracks common to the slated limestones. To 
the naked eye the rock is uniform in texture and composition, but 
under the microscope a thin section shows stratification caused by vari- 
ation in the amount of quartz present in the different laminae. 
The largest exposures of this rock are on a hill about half a mile 
west of Spragueville and on the North Branch of the Presque Isle 
River, where it crosses the corner of Chapman Township. The rock is 
identical in both places, and only the Chapman section will be described. 
Rising from the river at Littlefields is a low, rounded hill or ridge, 
which is partly bare of vegetation and shows a number of good expos- 
ures. At the eastern base is a light-gray limestone, in places quite 
pure and uniform, but for the most part composed of angular frag- 
ments of limestone closely cemented together and containing numerous 
brachiopods and other fossils. This is apparently the same limestone as 
that observed on Dudley's farm, 3 miles to the northwest. In one place, 
near the northeast base of the hill, a contact between the white lime- 
stone and the arenaceous limestone was observed, and from the condi- 
tion of the rocks it seems evident that crushing has taken place along 
the contact plane. A confused mass of pebbles of the two rock types 
now represents the contact. 
Joining the fossiliferous limestone on the west is the arenaceous 
limestone, which is here shaly, weathers yellow brown in distinct zonal 
banding, contains many large, rounded nodules and lenticles of the 
same material, and is marked by Orthoceras fragments. 
Farther up the hill the rock has a dark-gray color, is broken into 
thin slabs, and glistens with micaceous specks. The fossils here are 
graptolites. The rock nearest the hilltop is more sandy and contains 
crinoids, corals, and other organic remains. 
Judging from the position of the fossils, the beds of this series 
strike N. 35° E. and dip W. < 60°. Intersecting cleavage planes have 
broken the strata into blocks. 
Under the microscope slides prepared from rocks of this class 
showed that calcite in rounded or irregular grains and in strings and 
