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SHALLOW WELLS.-In this as in the other Eastern Shore counties bordering on the Bay the inhabitants of the low lands of the Talbot terrace obtain abundant supplies of water in the sands of the Talbot formation at depths of from 10 to 15 feet, or sometimes at slightly greater depths. This water has the usual advantages and disadvantages of surficial waters, the ease of reaching the water table being offset by the danger of contamination and the uncertainty of the supply during periods of dry weather. Since the major portion of the county is covered by the deposits of the Wicomico formation domestic supplies can be obtained from these at depths of from 15 to 45 feet. Sudlersville and Church Hill, both at an elevation of about 65 feet, furnish the records for the deepest Wicomico wells, although they are probably duplicated at a good many other places. At Ingleside, Barclay, Tilghman, etc., the Wicomico supply runs at the more common depth of 18 to 30 feet. The Wicomico water is consistently good, in the absence of direct pollution, and is a very valuable source of potable water.

CAROLINE COUNTY

Caroline County lies almost entirely on the broad central divide of the Eastern Shore which is formed by the sandy loam of the Wicomico formation. This is known topographically as the Wicomico terrace or plain. This plain has been moderately dissected by streams, although over extensive areas it is still an almost level country lying from 40 to 60 feet above sea level. Three wide tongues of lower-lying plain penetrate the county from the south along the valley of the Choptank River, Tuckahoe, and Marshyhope creeks. This plain, which is known as the Talbot plain, is less dissected than the higher Wicomico plain and ranges in elevation from sea level to about 30 feet. Federalsburg is situated on this plain and Denton is situated at the junction of the Wicomico and Talbot plains on the steep slope that usually separates these two levels.

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GEOLOGY

The surface of the county is made up almost entirely of the loams, sands, gravels, and marsh lands of the Talbot and Wicomico formations previously mentioned. There are a few limited exposures of the older Miocene along Tuckahoe Creek and on the upper Choptank River. The Choptank formation of the Miocene underlies the southern part of the county at no great depth, but is unimportant as a water-bearing horizon within the limits of this county. Beneath the Choptank is found the Calvert formation of the Miocene, a thick series of sands and clays underlying the whole county and an important source of artesian water. Still deeper the successively elder formations of the Eocene and Cretaceous are encountered. These are prevailingly sands and clays, generally carrying an abundance of water but lying at great depths. Since the Calvert horizon is so much more easily reached and usually furnishes an abundance of satisfactory water it is seldom necessary to drill to greater depths, although there are several wells at Denton that draw their water from the Eocene which approach to within 200 to 300 feet of the surface in the northern part of the county. One well at Hillsboro reaches the Upper Cretaceous at 440 feet.

SURFACE WATERS

The surface waters of Caroline County are not important sources of supply because the large streams are all tidal and either salt or brackish, and the small streams contain very little water in dry weather. The streams all receive drainage from inhabited areas and are of doubtful sanitary character. These conditions have prevented the use of surface water and there is no prospect of its future development.

UNDERGROUND WATERS

Artesian Waters

The Choptank formation outcrops in limited areas in the southern part of the county, but of the wells whose records are available none is thought to encounter water in this formation. The amount of water contained is probably rather small and then, too, the horizon occupies an unfavorable position, since it is slightly too deep for shallow wells and too shallow for deep wells. The head on the Choptank water would not be very great.

The Calvert formation is the main water-container of this county and through its thickness of over 200 feet of clays and sands there are many streams of water, some of which seem to owe their pressure to the local character of the bed or to the transition from a sand bed just before it graded into a clay, which would obviously get a much greater flow than if the sand were continuous. The Calvert formation is made up of clays and sands, and the notable impossibility of correlation of some of the water horizons with other wells close at hand is quite probably due to this gradation of materials. The wells at Ridgely 80 to 85 feet deep encounter a soft water that rises to within 6 feet of the surface. At Greensboro and Hillsboro, both along the strike with Ridgely, the wells are deeper. At Hillsboro recorded wells are 102, 145, and 165 feet deep, all drawing from Calvert horizons, the 141- and 165-foot wells probably drawing from the same stratum. These wells have a small flow of soft water. At Greensboro two wells 180 feet deep contain water reported hard and containing sulphur. The water in these wells has only head enough to bring it to the surface, while another well 160 feet deep containing similar water flows 80 gallons a minute. In these Greensboro wells the water comes from 120 feet. At Federalsburg, wells find water in the Calvert at depths of 230 to 285 feet with a head sufficient to give flows of 10 to 35 gallons a minute. The water in the shallowest well of this series is hard and contains iron, but the others report soft water. Records of four wells show flows obtained at the various depths: 150 feet, 3 gallons; 248 feet, 35 gallons; 255 feet, 20 gallons; 285 feet, 15 gallons. The 248-foot well shows water at 90 and 150 feet; the 255-foot well shows water at 180 and 210 feet; and the 285-foot well shows water at 160 feet.

A generalized section of one of the city supply wells, 248 feet deep, is given below:

Sand and gravel..

Marsh mud, bad odor.

Blue sandy clay.....

Fine sand and gravel...

WELL AT FEDERALSBURG

Very fine bluish sandy clay......

Shell rock with iron ore alternating with fine blue sandy clay.

Shell rock bands varied in thickness from 1 to 14 feet.

Feet

0-10

.10-20

20-28

28-36

.36-70

.70-248

Other wells at Federalsburg varying in depth from 133 to 185 feet find flows in higher beds of the Calvert. The Federalsburg wells with their various depths are a striking demonstration of the richness of the Calvert formation in water beds.

The Eocene water is reported from only two localities in Caroline County, but it probably underlies the whole county at depths of from 200 to 500 feet. The wells at Greensboro and Denton strike the characteristic hard water at depths of 240 to 285 feet. These wells have a small flow dependent on the elevation of the mouth of the well. The first city well at Denton was a non-flowing well, the second one was drilled down near the river and it flows. The wells at West Denton, 350 and 400 feet deep, indicate a second Eocene level. The shallower well flows 120 gallons a minute, while in the second one the water stands within 20 feet of the surface. These two wells and the city wells at Denton noted above show the control of elevation upon the head of water in a well and they clearly demonstrate the basic falseness of a classification which makes flowage the criterion of an "artesian" well.

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A well at Hillsboro 440 feet deep has a -22 head of good water. At 300 feet the well passed through " gunpowder material" (Eocene) and is probably drawing from a bed in the uppermost Matawan. This is the only well in the county that gets so low in the column.

Caroline County has a large supply of artesian water in the Calvert and Eocene beds, and by locating on low land the wells should be made to flow. However, the water should everywhere rise within easy pumping distance.

Non-Artesian Waters

SPRINGS. The flat nature of the country has not been favorable for the formation of springs and they are practically absent throughout the county, making it necessary for the inhabitants to rely upon wells for domestic and farm purposes.

SHALLOW WELLS.-The shallow wells of Caroline County draw their supply from the surface waters of the Pleistocene sands and gravels, and since the Talbot is only represented in a few areas along the larger streams

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