SHALLOW WELLS.-In Talbot County the shallow wells drawing, as they do, from the thin cover of Pleistocene sands, have the usual range in depth of from 8 to 20 feet, and the most common depths are about 10 to 15 feet. Locally driven wells have been sunk to depths of 40 and 45 feet, as at Skipton, but such wells are comparatively rare, and the majority of the inhabitants of the counties, except in the larger towns, use water from wells less than 20 feet deep. These shallow wells encounter water in beds of sand and gravel belonging to the Talbot and Wicomico formations. This shallow water is quite commonly marshy, coming probably from beds containing a large amount of vegetable matter, and in a few places the water tastes strongly of iron due to the amount of that mineral contained in the pebbles or nodules of the Pleistocene.

In a few places near the shore the water contains considerable salt, enough to render it brackish. This is most noticeable on some of the low islands, but it has also been reported on the mainland near tide water.

DORCHESTER COUNTY

Dorchester County is situated in the southern part of the Eastern Shore, and is almost surrounded by the waters of the Choptank River on the north, Chesapeake Bay on the west, and the Nanticoke River on the south and east. Most of the county is low and flat and imperfectly drained, and hence it includes a greater area of swamp and marsh land than any other county in Maryland. This is especially true of the southwestern portion. In the northeastern part of the county the divide between the Choptank and Nanticoke rivers, as far south as the vicinity of Linkwood and Reids Grove, is a nearly flat plain above 30 feet in elevation and gradually rising toward the northeast, until in the extreme northern part of the county it reaches elevations of 50 feet. In the remainder of the county lying southwest of this area and in the major stream valleys within this area the land is less than 30 feet above tide, and extensive areas are almost at tide level and form undrained marsh lands of great . extent.

Although Dorchester County is underlain by the successively older Miocene, Eocene, and Cretaceous formations, the amount of erosion is so slight that the streams have not cut through the surficial mantle of loams and sands of the Wicomico and Talbot formations. As mentioned in the preceding section, the northeastern part of the county consists largely of the Wicomico plain and the balance and major portion of the county is made up of the lower-lying Talbot plain.

SURFACE WATERS

The surface streams are for the most part tidal and unsuitable for use. The smaller streams carry no large amounts of water, fluctuate from season to season, are apt to contain a great deal of vegetable matter in suspension, and since all receive the drainage from inhabited areas they are liable to pollution and are unsuitable as sources of domestic or municipal supplies.

UNDERGROUND WATERS
Artesian Waters

There are four horizons in Dorchester County that are furnishing water for artesian wells, one in the lower Calvert, one at the base of the Choptank, one in the Nanjemoy level, and a level which seems to be the upper

Matawan, corresponding to that found in Talbot County at Easton and Oxford at 570 and 540 feet. This Matawan level along with the Nanjemoy supplies by far the greater number of the wells in this county.

CHOPTANK WATER.—This horizon is a purely local supply and furnishes the water for the artesian wells at three neighboring towns, Eldorado, Brookview, and Vienna. These wells have a similar depth and all have a slight flow of soft water. Logs of two wells were secured, one at Eldorado and one at Vienna.

These logs are not detailed enough to allow any fine differentiation. The materials are all Miocene, and probably the complete section includes parts of two of the Miocene formations, the St. Mary's and the Choptank. The Eldorado well flows 8 gallons a minute at an altitude of 13 feet above sea level. The Vienna well flows 4 gallons a minute at very nearly the same altitude as the Eldorado well.

This horizon is a good source of water, but it is very doubtful whether it has a wide extent. It is more likely a water-containing sand lens of restricted distribution.

BASAL CALVERT WATER.-The wells drawing their water from the lower portion of the Calvert are in the eastern part of the county and,

strangely enough, the records of deep wells in the northwestern part make no mention of any water at the depth where the Calvert might be expected. Wells have been sunk to near the base of the Calvert formation (as in other parts of the Coastal Plain the basal Calvert is usually encountered within 50 feet above the base of the formation) at East Newmarket where the town-supply well is 290 feet deep, at Hurlock 228, and at two localities near Secretary 250 and 280 feet deep. The well at Hurlock struck two streams of water, the upper one, which is cased off, at 192 feet and the lower, the one in use, at 250 feet. A log of this well is given below:

Of these wells only one, the 250-foot well northeast of Secretary on the Choptank, flows, and this well flows 3 or 4 gallons a minute 8 feet above sea level. The other three wells have good heads, about 15 feet above sea level, but since the surface at all three localities is beyond the limit of flow they must be pumped.

The distribution of the Calvert water might at first glance seem to be very fortuitous and the failure to find this stream in the western part of the county might be ascribed to faulty methods of drilling or to other human errors if it were not for the consistent agreement of numerous drillers, all of them pastmasters of their trade. However, from the records of several wells in the northwestern part of the county and from

the evidence afforded by a well sample from near Gum Swamp, it seems possible that the Calvert water is absent because of subsurface irregularities. This will be discussed more fully further on.

NANJEMOY WATER.-This water bed, which supplies several localities in Talbot County, assumes great importance in the northwestern part of Dorchester and supplies the large amounts of artesian water used at Cambridge and the immediate vicinity. The wells in this neighborhood are drilled to a depth of 320 to 390 feet, the variation being due to differences in elevation and position along the dip. The public supply of Cambridge comes from six wells about 375 feet deep which yield an alkaline, soft water. The following analysis is of the water as furnished to the residents of Cambridge:

There are several other wells at Cambridge that have very nearly the same depth and which yield the same alkaline water. The well at the Eastern Shore State Hospital, about 1 miles east of Cambridge, is 390 feet deep and belongs to this group.

The amount of water yielded by the individual wells has shown progressive decrease since the horizon was first tapped in this vicinity in 1888. The first wells sunk had good flows, but since the addition of so many wells in later years the flows have ceased and the water now stands a few feet below sea level. Not only has the head diminished, but in the canning season when the wells at the canning factories are pumped hard and also