granite, serpentine, gabbro, phyllites, and gneiss, and outcrop as shown on the geological map of the county published by the Maryland Geological Survey. A part of the area is described in the Tolchester folio of the U. S. Geological Survey and the whole district will be described in the county report of Harford County in the course of preparation by the Maryland Geological Survey. The Coastal Plain portion which lies almost entirely to the southeast of the Baltimore and Ohio Railroad comprises sands and clays of Cretaceous age and surficial sands, gravels, and loams belonging to the Pleistocene terrace formations which are geologically very young. SURFACE WATERS There are no large streams in the county except the Susquehanna River, which forms its eastern boundary, and the Gunpowder which forms its western boundary. The latter is utilized for the Baltimore City supply and the former furnishes the public supply of Havre de Grace, and is an abundant source of water power which it not, however, utilized in the county. The surface streams within the county are all small except the Bush which is a tidal estuary. Because of their small size and liability to contamination the small streams are not usually fit for domestic use. UNDERGROUND WATERS There are relatively few deep wells in the county and the amount of information concerning them is so limited that it is difficult to formulate a satisfactory statement of the possibilities of future development. In the Coastal Plain portion of the county the Cretaceous sands usually contain an abundant supply of water at no great depths, but in the Piedmont portion, since the water is found in joints and fault plains and the rocks are much contorted, there is no definite clue to what the driller will strike. There are several wells at Aberdeen, one on the property of Charles C. Brown, 233 feet deep, in which the water rises to within 2 or 3 feet of the surface and pumps 60 gallons a minute of slightly hard water. The Belair Water & Light Company utilizes the Wallis Spring and has two driven wells 2 miles northwest of the town. These are 6 inches in diameter and 300 and 333 feet deep respectively. The water is of good quality, heads 8 feet below the surface and pumps 70 gallons per minute. The town of Cardiff is partially supplied by 200- and 230-foot 6-inch wells located at Delta across the Pennsylvania line. A number of wells have been put down at Havre de Grace. These range from 43 to 200 feet in depth. The shallower draw their supply from the upper surface of the underlying crystalline rocks and yield large quantities of soft water which is admirable for manufacturing purposes but liable to surface contamination and hence should be used with caution for domestic purposes. The deeper wells, 100 to 200 feet deep, also yield an abundance of water, 60 to 100 gallons per minute, heading about 20 feet below the surface. There are two successful wells at Sharon. The following records of wells at Van Bibber well illustrate the variations in materials encountered in the Coastal Plain portion of the county: ALTVATER AND SCHOENHALS WELL, 2 MILES WEST OF VAN BIBBER J. T. NORRIS' WELL, 3⁄4 MILE NORTHEAST OF VAN BIBBER SPRINGS. There are large numbers of small springs throughout the hilly portion of the county, utilized locally for domestic purposes. The town of Aberdeen with a daily consumption of 50,000 gallons is supplied by a spring from which the water is pumped into a standpipe giving a pressure of 50 to 60 pounds. Belair obtains part of its supply from the Wallis Spring and springs form the principal source of supply at Magnolia. It is possible that some of the springs may have medicinal value, although the only mineral spring noted is a large sulphur spring at Abingdon. SHALLOW WELLS.-Throughout the farming districts and in the small towns dug wells are relied upon for domestic purposes. These range in depth from 10 to 100 feet and can usually be depended upon to yield a moderate supply which is generally reported as of excellent quality. In the more thinly settled portions of the county, if care is taken in the location and pollution is prevented, such wells are eminently satisfactory. BALTIMORE COUNTY Baltimore County, centrally located and surrounding Baltimore City, is the most populous county in the state. It extends from tidewater on the Patapsco, Back, Middle, and Gunpowder rivers to the Mason and Dixon Line, which separates it from York County, Pennsylvania, on the north. The river necks of the southeastern border are low, flat farming lands of the Coastal Plain district which rise and become more broken toward the "fall line." The fall line separates the Coastal Plain from the Piedmont Plateau and is a transitional zone approximately marked by the line of the Baltimore and Ohio Railroad. Northwest of this line and comprising most of the area of the county the country is a much broken upland with high ridges and narrow stream valleys which gradually rise from elevations of from 100 to 200 feet along the "fall line" to over 800 feet in the northern part of the county. The average elevation is well over 300 feet. Except for the limestone valleys, like the Green Spring, Worthington, and Dulaney valleys, the country is sharply broken and the stream valleys are narrow, particularly toward the north and west, often forming rocky gorges, like those of the Gunpowder, Jones Falls, Gwynns Falls, and Patapsco. The southern and Coastal Plain portion of the county is low and flat, the topography of which is dominated by the surface mantle of sands, |