Geological Survey of the Environs of Philadelphia

30 bushels alluvion Alumina amphibolic rocks analyses Atlas average Blockley township bushels of corn bushels of oats bushels of rye bushels of wheat Byberry Byberry townships Carbonate of lime Chesnut Hill chlorite clay clayey colour containing creek crop Delaware river diabase disintegration eurite farm farmers feldspar fertile finely divided matter geological Germantown gneiss grain granite gravel ground hay per acre Holmesburg impalpable matter kaolin light sandy lighter nature limestone valley loam Loss by vegetable manure Marsh township mica slate micaceous miles nearly ophiolite Oxide of iron pegmatite Philadelphia places Poquessin Price produces quantity quarried quartz Radnor township raised rocks prevail Roxborough sand sandy loam Schuylkill serpentine formation sheet Map Silex slaty soapstone sometimes South America spots Spring Mill Springfield stiff stone strata stratum subordinate subsoil talc talcose tion tons of hay township Upper Dublin upwards vegetable fibres vegetable matter veins vicinity wheat per acre White Marsh Willow Grove