and an abundance of water can be obtained from dug wells of shallow depth. On the narrow divides, however, the water table during dry seasons sinks almost to sea level and thus necessitates wells of considerable depth. On the other hand, on the broad, low-lying flats bordering the Potomac dug wells rarely need to be over 20 feet in depth and sometimes the water in them rises nearly to the surface. The water in these shallow wells is very apt to contain impurities, usually of organic origin, although iron salts are also liable to be present in greater or less amounts. Some of the wells on St. George Island are only 12 feet deep and the water in these is more or less brackish because of seepage from the river. The location of shallow wells in or near settlements should be given very careful consideration, since most of the villages are on hills and household drainage is especially liable to contaminate the wells. COUNTIES OF CENTRAL MARYLAND Harford County lies to the west of the headwaters of Chesapeake Bay and extends to the Pennsylvania line. Over three-quarters of its area is in the Piedmont Plateau district and is a gently rolling upland, while the southeastern quarter is in the Coastal Plain district and is low and flat. The Piedmont portion of the county is formed by the very ancient crystalline and sedimentary rocks of igneous and metamorphic origin which are much folded and faulted. These comprise quartzite, slates, 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 Artesian 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, 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 |