182 KECOKD OF DEEP- WELL DRILLING FOR 1905. 
DETAILED RECORDS. 
The records which follow were selected from the great number listed 
in the preceding table because of the stratigraphic information which 
they afford. They do not always represent the deepest borings 
reported from a particular section, nor are they necessarily records oi 
wells from which samples have been received by the Survey. They 
were chosen mainly with the view of supplying data for those locali- 
ties in which information is deficient. In discriminating among well 
records within a given area those which showed the most care in re- 
cording naturally received preference. The logs are reproduced mainly 
as given by the driller, although obvious mistakes were corrected and 
occasional changes made in the nomenclature, such as the substitu- 
tion of " shale" for u soapstone" where it was clear that the former 
was the proper term. In some cases where no logs accompanied the 
samples, but the latter had been taken at fairly close intervals, records 
were compiled from them. Where the driller's notes and the samples 
have varied decidedly as to the character of the rocks at a given depth, 
the original name is followed by a description of the sample in paren- 
theses. The Survey has attempted to publish only reliable records, 
but, owing to the absence of any opportunity for verification, can not 
guarantee them. It is hoped, however, that they will be of aid to 
drillers by showing the character of the rocks; the types of rig used, 
the depth to the oil or water bearing horizon, the size and length of 
casing probably needed, etc. Companies or individuals prospecting 
in unfamiliar territory should also find among these records informa- 
tion that will be of service to them in many ways. 
In some of the logs the samples are described in detail, even though 
the exact depths of the beds are not given. This is for the purpose of 
showing the general character of the rocks. While drillers employ 
certain terms which are descriptive and, if properly used, sufficiently 
exact, such as " slate," " shells," " shelly slate," etc., yet usage varies 
enough to make records containing such entries puzzling. Again, 
rocks are not always properly differentiated; u sand" is frequently 
any rock gritty enough to wear the bit, hence limestone and sandstone 
are confused, which results in great difficulties in stratigraphic cor- 
relations. On the other hand, while a sample of pulverized rock is of 
little or no value unless the location of the well and the depth are 
known, and while in drilling with a standard rig pieces of crumbly beds 
may fall and mingle with the pieces of the bed on which the drill is 
pounding, and with a hydraulic rig other contamination of samples it 
likely, yet a series of samples carefully taken from top to bottom of i 
well, even if unaccompanied by the driller's notes, gives evidence o: 
high reliability. As a bed deeply buried often differs much from it; 
outcrop, samples from a number of deep wells are described in som< 
detail. 
