112 “ Turtle-Back” Celts in District of Columbia. [February, 
of the city of Reading, and another a short distance below that 
city. The rude implements found at these places have been 
remarked upon by Mr. A. F. Berlin in a recent number of the 
American Antiquarian? The first named locality is the one upon 
which Mr. Berlin first noticed the occurrence of rude implements 
bearing the typical characteristics of so-called “turtle-backs.” A 
few days after this discovery I visited the place, and found 
various examples, consisting of “ celts,” spear-heads, arrow-heads 
and scrapers. These were found over a small area only, occupy- 
ing the top of a small limestone bluff. A small stream known as 
Mineral Spring creek passes near the base of this bluff, the inter- 
vening soil consisting of loam and débris from the more elevated 
regions. Immediately above, and resting upon the stratum of 
limestone, is a stratum of sand and pebbles, which has been 
washed away along the immediate declivity of the embankment, 
exposing the rude relics above referred to as found by Mr. Berlin. 
I found that this stratum of sand was covered by earth and gravel 
from the neighboring hillside, with which it was continuous, 
excepting along the greater declivity where the rain had worn 
away the super-stratum, exposing the sub-stratum of sand and 
rounded and worn pebbles, which occurred in accumulations 
where they had been washed into the ravines. Modern types 
were also found here associated with the rude implements, but 
the latter were not found on the upper stratum, even where the 
ploughing of long continued cultivation and local denudation has 
removed considerable soil ; but farther down the modern forms 
have been washed down and lowered by the removal of sand and 
earth to reach the more ancient stratum containing the “ turtle- 
. backs.” 
This stratum of sand and gravel, or, more properly speaking, 
pebbles, continues eastward horizontally, as was proven by: the 
digging of a well. Nearer the hill, where this excavation was 
made, the workmen reached a layer of stratified sand, pebbles 
and cobble-stones at a depth of about forty feet. Upon examina- 
tion this proved to be the level (if run horizontally towards the 
bluff) of the one containing the implements. Since then this 
stratum has been detected along the valley a short distance, 
proving it to be the same, the great amount of débris and soil 
from the mountain side being accounted for where the well was 
1 Vol. i, No. 1, 1878, pp. 10-12, pl. facing p. 16, 
