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GEOLOGY OF THE FIRST DISTRICT. 
Smoothed and Scratched Surfaces of Rocks. 
In many parts of Europe and America, the rocks have been found beneath the superficial 
materials of the earth, with smoothed surfaces, as if ground off by attrition. They are some¬ 
times smooth and polished ; sometimes scratched, grooved and furrowed, on the smooth sur¬ 
faces. The cause that has produced the scratches and smooth surfaces seems to have acted 
in a nearly uniform direction in each locality, conforming to the great topographical features 
of the country to a certain extent, but with numerous local variations, which are, it is believed, 
capable of a satisfactory explanation. Various theories have been offered to account for these 
appearances, which are observed on elevated grounds and high mountains, as well as on plains 
and in valleys. The principal are, first, the attrition caused by powerful currents of water 
moving gravel, pebbles, boulders and blocks along the surface ; secondly, floating ice having 
these materials imbedded in their mass, grinding along the bottom, where the water was not 
deep enough to float them clear ; and thirdly, glaciers with rocks, etc. imbedded, and sliding to 
a lower level, as we now see in elevated districts, above and near the region of perpetual snow. 
A great number of examples of these smooth and scratched surfaces have been observed 
in the First Geological District; and for conciseness and facility of reference, those detailed 
will be put in a tabular form. Great numbers that were observed were not registered, for 
they were so common that the localities would fill a volume, and would be useless repetition; 
but enough have been registered to show the general direction of the action of the forces 
causing them, and the numerous local deflections, the resultant apparently of the resolution 
of two or more forces acting obliquely to each other. 
The grooves, scratches and smooth surfaces are most frequently seen on level or slightly 
inclined surfaces of the rock, but they have in many instances been observed where the sur¬ 
face of the rock was inclined 45°, 50°, and even nearly perpendicular. In these cases, the 
mass causing the scratches seemed to have been deflected from its course after meeting these 
obstructions ; grinding and rounding off the irregular parts of the rock in place, and sliding 
off again into deeper water. 
The scratches are found on all the consolidated rocks in place that have been protected by 
a covering of loam or clay, and that do not disintegrate below the surface when covered with 
such materials. The harder rocks (with the exception of the slate and talcose rocks of the 
Hudson and Taghkanic groups) show the scratches most distinctly, as the trap, granitic, 
gneissoid and conglomerate rocks, and the hard blue limestones and grey grits. 
The examples observed in the First district of New-York will first be adduced ; then others 
in other portions of our country, that may eventually aid in the determination of the causes 
of the drift. Where the direction of the scratches is not noted in the localities in the First 
district, it was in most cases from fifteen to twenty degrees west of north and east of south, 
in the eastern part of the Champlain and Hudson valley. 
