84 
GEOLOGY OP NORTH CAROLINA. 
Snow . — The records of the stations are not full enough nor of suffi- 
ciently long continuance to give entirely satisfactory results, in regard to 
the amount and distribution of snow, but the observations of 17 stations 
in 1872, show that the total fall of snow for that year averaged 6 inches 
for the whole State, 4 inches in the mountains, and 6^ in the middle and 
eastern divisions ; and the average for three years, (including 1872), for 
the State, deduced from observations at 5 stations, is also b inches, the 
largest average for a single station, 11^ inches, occurring at Boone. It is 
proper to state that the average for a larger number of years will proba- 
bly be somewhat above the amount given by these last three, as this feat- 
ure of the winters in this latitude is very variable, in some winters a fall 
of 4 or 6 inches occurring at one time, and at lung intervals even 10 and 
12 inches, as in 1857. 
It is observable that the yearly amount of snow-fall is not greater in 
the mountains than in the cismontane regions. This result traverses the 
common impression ; but there is a strong confirmation of it in the well 
known fact, attested by the most intelligent observers, that the wild 
mountain pastures do not become inaccessible to cattle grazing, by reason 
of the obstruction of snow, oftener than about once in seven years. 
Frosts . — The first frosts of autumn may be expected about October 
13 ; occurring once in the last three years on the 2nd., at three of the 
western stations, and as late as November 4, at one point of the eastern 
division ; and the date of the last frost of spring is about April 21 ; oc- 
casionally falling however, as early as the 13th, and once in the three 
years, at some of the mountain stations, quite abnormally, as late as 
May 20. 
There are portions of territory in the western region, that are exempt 
from frosts altogether. These are found in narrow zones along the flanks 
of various mountain ranges, and are known as “ frostless belts.” They 
are from a few rods wide to several hundred yards, and their boundaries 
are said to be very narrowly defined and to remain quite permanently 
fixed. Mr. Silas McDowell, a very intelligent observer in Macon county, 
seems to have been the first to call attention to this fact ; and he has 
traced the limits of some of these tracts, and finds the lines so sharply 
drawn, that one half of a shrub will be frost-killed, and the other un- 
affected. It would occupy too much space to discuss here the causes of 
this phenomenon ; suffice it to say, that it is due to the nocturnal sratifica- 
tion of the atmosphere of these mountain-enclosed basins, the different 
horizontal belts, having different degrees of humidity, whereby the sur- 
face radiation is controlled. 
The point of practical interest is, that within these favored limits, 
