6 BULLETIN OF THE LABORATORIES 



The river terraces are composed of glacial drift. This drift is 

 generally composed of sand or gravel, the gravel being of a varied 

 composition. Granite, diabase, diorite, schists, slates, and limestone 

 are a few of its components. It is on these wooded terraces that the 

 flora is the most varied. One hundred and twenty-five species have 

 been collected from a space only forty feet square, (Maple Grove 

 Cemetery, Granville.) In the eastern part the hills are still higher, 

 the native rock being a coarse sandstone or sandstone conglomerate. 

 This sandstone weathers very slowly. In consequence of this the soil 

 is scant, the valleys narrow and in many places simply gorges. The 

 strata of the county are referred to the Waverly and Carboniferous, 

 the latter occurring only in the eastern part. The southern part is 

 low and covered to a depth of many feet with an alluvial deposit. 

 Formerly a greater part was covered by swamp.* 



Altitudes of Different Points. 



Hartford, n 60 feet. 

 Alexandria, 950 feet. 

 Granville, 906 feet, at depot. 

 Hebron, 885 feet. 

 Jacksontown, 1075 feet. 



" I2 35 feet, hill south of town. 



Newark, 791 feet. 



Rainfall, Temperature, Etc. 



The meteorological observations have been so scattered that it is 

 impossible to give more than approximate data. 



The rainfall averages about 40 inches a year. The least which 

 has been recorded, is 24.89 in 1856, the greatest 61.51 in 1852. The 

 average of the different months is about the same. 



The highest temperature recorded is 94.5 deg. ; the lowest tempera- 

 ture recorded is 18 deg. below zero. 



The prevailing winds are from the west. 



The 40th parallel of latitude runs through the southern portion 

 of the county. 



-Only a general sketch is here given of the main features of the geological 

 structure of the county. A complete description has been given by Prof C. L. 

 llerrick, in the preceeding volumes of this Bulletin. 



