Abbildungen der Seite
PDF
EPUB
[graphic]

No.

16 10th & S. C. Ave. SE.
17 14th & C Sts. SE.
18 12th St. SE.

19 2d & M Sts. SE..
20 15th & Md. Ave. SE.
21 2d & N.. C. Ave. SE.
22 8th & O Sts. SE.
23 B & Warren Sts. SE.
24 460 K St. NW.
25 1st & M Sts. NW.
26 1st & M Sts. NW.
27 1st & M Sts. NW.
28 1st & M Sts. NW.
29 11th & G Sts. NW
30 12th & U Sts. NW
31 12th & U Sts. NW
32 12th & U Sts. NW.
33 15th & M Sts. NW
34 15th & M Sts. NW

[ocr errors]
[ocr errors]
[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][subsumed][merged small][merged small][merged small][merged small][merged small][merged small][merged small][subsumed][merged small][merged small][merged small][merged small][merged small][merged small][merged small][subsumed][ocr errors][ocr errors][subsumed][subsumed][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]
[blocks in formation]

Reddish brown sandy clay containing concretions of iron ore...... 80-120 Dark gray clay containing a little sand and a few concretions of iron

[blocks in formation]

Bluish gray crystalline rock (probably boulders or cobbles of rock

[blocks in formation]

Very coarse gravel with quartz and crystalline rock pebbles.
Finer gravel

...370-379

.379-382

Piedmont.

Fine gray arkosic sand, a weathering product of the underlying crystalline rock becoming harder towards the base...

Gray crystalline rock.....

.400-440 .440-590

ARTESIAN WELL PROSPECTS.-The lists of wells shown in tabular form are the results of deep drilling in the District of Columbia. An examination of these lists will indicate the approximate depths to artesian water in different parts of the District, and in sinking wells drilling should usually be continued to the crystalline rocks unless satis

factory supplies are encountered from higher horizons. However, on the high hills south of Anacostia River deep drilling is apt to be disappointing because of the low head of the water.

WATER RESOURCES OF DELAWARE

INTRODUCTORY

The State of Delaware possesses an abundant supply of water throughout its entire territory. Most of this is underground, or in shallow streams which generally are of little or no service for power or drinking purposes. The waters themselves vary widely according to the underlying rocks and the topography.

RAINFALL

The rainfall in Delaware averages from 35 to 50 inches annually, and is distributed rather uniformly over the state throughout the year. No locality averages less than 2 inches per month and none more than 5. The maximum and minimum precipitation varies from place to place with the succeeding months and seasons, but in general there is less precipitation along the Atlantic at Rehoboth and Lewes and along the Delaware from Port Mahon to Wilmington than farther inland along the Chesapeake-Delaware divide and the shallow valley of the upper Nanticoke near Seaford and Laurel. The accompanying tables give the approximate average rainfall by months, seasons, and year for eight localities.

TABLE OF AVERAGE MONTHLY PRECIPITATIONS IN INCHES

Wilmington Newark Newcastle Dover Milford

Lewes
Seaford

Millsboro

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. ..3-4 3-4 3-4 3-4 2-4 3-4 4-5 3-4 3-4 2-3 3-4 3-4 .3-4 3-4 3-4 3-4 4-5 2-3 4-5 3-4 3-4 2-3 3-4 3-4 2-3 2-3 3-4 3-4 3-4 4-5 3-4 3-4 3-4 2-3 2-3 4-5 3-4 3-4 4-5 3-4 3-4 3-4 4-5 3-4 3-4 3-4 3-4 3-4 2-3 4-5 3-4 3-4 4-5 3-4 4-5 3-4 4-5 3-4 3-4 2-3 4-5 3-4 4-5 1-2 1-2 2-3 2-3 3-4 2-3 2-3 2-3 2-3 2-3 3-4 3-4 4-5 4-5 2-3 4-5 3-4 3-4 3-4 3-4 2-3 2-3 4-5 3-4 4 4-5 3-4 4-5 3-4 3-4 3-4 3-4 2-3

[blocks in formation]

This annual rainfall represents about 100,000 gallons per acre per month which falls upon an unusually porous soil that retains more than. the average amount, and yields the same quite regularly and easily through springs and wells in the Wicomico and Talbot terraces. Since practically all the waters, surface and underground, originate in catchment areas within the limits of Delaware and peninsular Maryland, the amount and seasonable distribution of the rainfall have more than usual immediate relation to the water resources of the state.

HYDROGRAPHIC AREAS

The state is divided into two major divisions by a line passing from the Delaware River through Wilmington and Newark to Elkton, Maryland. North of this line the topography is rugged and the underlying rocks highly metamorphosed crystalline schists, gabbro, and smaller bodies of limestone. South of this line the area is characterized by low relief, sluggish streams, and more or less unconsolidated clays, sands, and gravels. The former may be designated as the Piedmont area, the latter as the Coastal Plain area.

Piedmont Area

This area, bordered on the north by the circular boundary, on the south by the above-described line from Wilmington to Elkton (approximately parallel to the Baltimore & Ohio and Pennsylvania railroads), comprises approximately 150 square miles. It contains the remnants of the old base-leveled surfaces of the Piedmont and their seaward margins which have been dissected by the streams which cross the area into the

« ZurückWeiter »