34 GEOLOGICAL SURVEY OF NEW JERSEY. 



growth ; or, more accurately stated, a forest 30 years old will 

 produce 30 cords, and one cord will thereafter be added each 

 year. Several recorded instances in Highlands forest, of about 

 average quality, gave an average yield of eight-tenths of a cord 

 yearly. Perhaps one cord per acre is not too high for the aver- 

 age of all deciduous forest, but the Highlands forests will not 

 exceed eight-tenths of this amount, while the red sandstone 

 forests will exceed it generally for second-growth timber. Sec- 

 ond-growth pine does not appear to increase faster than half a 

 cord yearly, even where it is protected from fire, in the light 

 sandy soils of the pine belt. 



GROWTH OF TREES. 



Having collected a considerable number of measurements of 

 chestnuts and oaks, with some hickories, maples and other trees, 

 I have attempted, in Plate No. II, to represent the approximate 

 curves of average growth of deciduous trees in northern New 

 Jersey. I have found no marked difference in rate of growth of 

 chestnut and oak or other trees. There is a noticeable difference 

 between the rate for the thinner soils, typified by the Highlands 

 plateaus and ridges, and the deeper soils of the red sandstone, 

 Kittatinny valley and the valleys of the Highlands. The growth 

 is consequently represented by separate curves for each. The 

 data are consistent up to about 70 years old, but beyond that 

 there is less certainty, and the variation of growth is large. 

 Thus a chestnut 70 years old was observed having a diameter of 

 60 inches, and which had one year increased its diameter one 

 inch. Near Camp Tabor a number of trees 35 years old ranged 

 from 24 up to 34 inches in diameter, and from 40 to 50 feet in 

 height. These were remarkable, but a diameter of 36 inches is 

 often reached before the age of 100 years, while a hickory 300 

 years old measured but 38 inches. The possibilities as to larger 

 size than our average are suggested in the list of large trees 

 previously given. Our curve of diameters would not reach 45 

 inches in 200 years, or 60 inches in 300 years, yet many of the 

 large trees exceed these measures, and it is not likely that many 

 of the trees are 300 years old. Some trees exceeding 100 years 

 of age measured as follows : 104 years, 30 inches ; 118 years, 25 



