SHALLOW WELLS.-The shallow wells of Dorchester County vary in depth from 8 to 50 feet, reaching their maximum in the eastern and higher part of the county where the Wicomico is thickest. The dug and driven wells in the low swamp lands and islands of the Chesapeake are seldom more than 14 feet deep and usually the water is very poor. Typical wells and depths are those at Hudson, 9 to 14 feet; Hills Point, Taylor Island, and Madison, 8 to 12 feet; and Lloyds, Cornersville, and James, 8 and 9 feet deep. The water frequently contains iron, although this mineral is very sporadic in its occurrence, but it is very readily noticed since it occurs in the form of an insoluble hydrate which will stain a cloth or will be deposited on the side of vessels. The organic matter frequently noticed in these wells is most likely derived from the swamp vegetation and thick muck of the lowlands, since the subsoil is very rich in decayed. vegetation to a depth of 8 or 10 feet.

These shallow wells have a very intimate connection with the rainfall, a heavy rain greatly increasing the supply and also bringing in large amounts of suspended soil, so that the water after a rain is quite muddy. The water level fluctuates with the seasonal rainfall and in some few cases falls below the well in extreme droughts. Prolonged heavy rains produce an immediate change, appreciably increasing the amount of water.

In the eastern portion of the county where the wells are deeper, commonly 20 to 30 feet, the water is purer and less likely to fail in dry spells. Most of these wells, like the shallower ones westward, draw from the Pleistocene deposits, but the materials are here coarser and allow more circulation so that organic impurities are more easily expelled. The depth to the base of the Pleistocene deposits cannot be accurately determined, but it is thought that the wells that, in the eastern part of the county, have been driven 50 to 60 feet below the surface, indicate the base of the Pleistocene sands.

The wells at Hurlock which supply the water for town use are shallow wells 50 to 55 feet deep. These wells along with one at Ralph 40 feet deep, one at Reids Grove 40 feet, and some of the wells at Eldorado 35 to 40 feet in depth are probably down to the base of the Pleistocene.

The wells which are drawing from the sands and gravels at the base of the Wicomico are usually somewhat shallower, typical wells being those at Ellwood 20 to 30 feet, Eldorado about 20 feet, Hurlock 15 to 25 feet, East Newmarket 15 to 30 feet, Williamsburg 30 feet, and Galestown 25 feet deep. The water is generally of good quality, carries varying amounts of iron and is more dependable than the shallower wells to the westward. That this water, however, is not very far removed from that in the Talbot is shown by the fact that one well, at the canning house in East Newmarket, went dry after several years, and at several other points the water level is noticeably depressed during dry weather.

The water in the shallow wells of the higher eastern part of the county is much more palatable than that from the low swamp lands along the Bay. Iron is sometimes present in objectionable quantities, but the excessive amounts of organic matter and salt which characterize the western wells are seldom noticed here, the salt never.

The taste of vegetable matter that has been reported from several localities, notably at Secretary, is due either to insecure casings, permitting seepage into the wells, or to contamination less direct, from dwellings, barns, or outhouses.

An example of the possibilities of properly constructed shallow wells is furnished by those which supply the town of Hurlock. This system, privately owned, consists of a battery of 13 driven wells, 13 and 14 inches in diameter, which supply to the town an average of 12,000 gallons a day, which is probably very close to the maximum yield of this system. This supply has lasted a good many years and has given good service for shallow wells, but it is doubtful whether a growing town like Hurlock will be able to depend upon this source much longer both because of the limited amount of water available and the danger of pollution in a thick settlement.

Shallow wells, then, may be expected to furnish fair amounts of good. water in the higher parts of the county, but to the westward and along the Nanticoke River the water will probably be salt, muddy, and generally objectionable.

WICOMICO COUNTY

Wicomico County, lying between Dorchester County, Maryland, and Sussex County, Delaware, on the north and Somerset and Worcester counties, Maryland, on the south, is a region of low relief. Its surface is essentially a plain but little dissected by streams and with broad, flat stream valleys. The streams are slow and considerable areas are covered with swamps. In the western part of the county there are extensive salt marshes along the Nanticoke and Wicomico rivers. The elevations range from only a few feet above sea level in the western part of the county to a maximum of 84 feet in the vicinity of Parsonsburg in the eastern central part of the county.

The geology of Wicomico County is monotonously simple, since at no point has an outcrop of any materials older than the Pleistocene been observed. The Pleistocene, however, is well developed and covers the entire county with a mantle of sands and sandy loams. Gravels are not so extensively developed as in the counties farther northward. The oldest terrace in the county is the Wicomico (named from its development on the Wicomico River in Charles and St. Mary's counties). It is delimited below by an escarpment at an elevation of 40 feet. Lying at a lower level

than the Wicomico is the Talbot terrace which extends from the 40-foot contour line down to sea level and is broken at several levels, notably at 30 feet, by minor intra-formational scarps.

The Pleistocene deposits are underlain by the Miocene deposits, a deep well at Parsonsburg showing that the several Miocene formations extend to a depth of about 1100 feet.

SURFACE WATERS

The only large streams in the county are the Nanticoke, which forms its northwestern boundary and expands in its lower course into a broad tidal estuary; the Wicomico, which rises within the county and is navigable for steamboats as far as Salisbury in the central part of the county; and the Pocomoke, which rises in Delaware and forms the eastern boundary separating Wicomico from Worcester County. There are many creeks, such as Barren, Rewastico, and Quantico, which flow into the Nanticoke; Rockawalking, Beaverdam, Tonytank, and Passerdyke, which flow into the Wicomico; and Nassawongo, which eventually reaches the Pocomoke; but none of these are of any size or commercial importance.

The Nanticoke and Wicomico rivers are tidal and the water is consequently salt or brackish. The smaller streams are sometimes dammed for grist mills, but the waters receiving the surface drainage of inhabited areas is unsanitary and should not be used for domestic purposes.

UNDERGROUND WATERS

Artesian Waters

Under this heading will be included all of the wells in Wicomico County, since even wells in the Talbot terrace are known to flow, and many wells on the Wicomico plain have large heads, frequently sufficient to cause overflows. Several wells have been sunk beyond the lowest Pleistocene horizon but none of these wells, among which the deepest was one 402 feet at Delmar, has been able to secure good water.