Ave. we reach, beyond W St., a series beginning Adams, Bryant, Channing, etc., Sts., and ending with Webster St., beyond which a second series begins with Allison, Buchanan, Crittenden, etc., Sts., closing with Whittier St.; while a third series follows, consisting this time of botanical names in place of famous Americans, namely: Aspen, Butternut, Cedar, etc., Sts., up to Poplar St., in the extreme northern corner of the District. Similar series will be found in the section N. of Georgetown, in the Benning section, in Anacostia,-in short, in practically all the suburban sections. The advantage, of course, of this system is that it enables any one, by a little calculating, to determine approximately the house numbers beyond any given street. Thus, since the first number beyond N. W St. is 2200, then the first number beyond Webster St. should be 4400, and beyond Whittier St. 6600. In point of fact, however, some confusion has been caused by the inclusion in some of these series of both an I and a J; while in at least one case the series does not stop with W, but includes a Y (Yuma St., in the Tenleytown section).

The monotony of the chequer-board pattern is, as already indicated, broken up by a multitude of small parks and circles, from which broad avenues radiate at a great diversity of angles. These avenues bear the names of the several states, the principal and more central avenues being naturally named from the thirteen original colonies, while many of the largest and most important western states must be contented with representation in the remoter districts. Pennsylvania. as the "Keystone State," gave its name to the city's principal thoroughfare, and direct line of communication between the Capitol and the White House, intersecting at the former point with New Jersey, Delaware and Maryland Avenues, and with projected lines of Vermont and Connecticut Aves., which are interrupted by Lafayette Square. Other important points of radiation are: Washington Circle (p. 218), Dupont Circle (p. 229), Thomas Circle (p. 228), Mt. Vernon Park (p. 225), and Lincoln Square (p. 366).

What impresses the stranger in Washington, next to the continual surprise of new and suddenly revealed vistas, is the spaciousness of all the streets and avenues. Of the lettered streets, the average width is 90 ft.; only three are less than 80 ft., while the widest, North K St., is 147 ft. Of the numbered streets, sixteen range between 100 and 112 ft. N. and S. Capitol Sts. are 130 ft. wide, E. Capitol St. and N. 16th St., 160 ft. each.

House numbers were first adopted by the city in 1854, and revised in 1869 on the basis of the so-called "decimal

system," the numbers starting from the central dividing lines marked by the Capitol Sts., and starting a new hundred beyond each street crossing. Accordingly even a stranger can readily determine the location of any given address: for instance, 815 North K St. would lie between 8th and 9th Sts., and similarly 422 West 4th St. would lie between D and E Sts.

In regard to the house numbers, it should be noted that in the case of the lettered streets the even numbers are on the side nearest the Capitol, while in the case of the numbered streets the even numbers are on the side furthest from the Capitol. Thus, for example, 304 C St. N. W. is on the S. side, while 714 F St. S. E. is on the N. side. The numbering of the avenues, while somewhat more confusing at first, becomes quite simple if one remembers that there are no avenues which run precisely Northeast or Northwest, but that they all slant at a small angle with either the lettered or the numbered streets. Accordingly the house numbers of the avenues obey respectively the rules for the streets with whose direction they most nearly coincide. Pennsylvania Ave., for instance, running almost E. and W., has its even numbers on the S. side west of the Capitol, and on the N. side east of the Capitol, after the manner of the lettered streets; while Connecticut Ave. N. W., running nearly N. and S., has its even numbers on the W. or further side, following the rule of the numbered streets.

One last source of confusion is caused by certain streets bearing half-numbers, such as 41⁄2 St. In such cases the house numbers do not begin with even hundreds, but with so-many-hundred-and-fifty; for instance, the building at the S. W. cor. of Pennsylvania Ave. and 41⁄2 St. is not No. 400 but No. 450.

b. The Geology of Washington

The District of Columbia lies within that lengthy section of the Atlantic coast consisting of a broad slope that descends from the Appalachian Mountains to the ocean and continues beneath it. This slope comprises two divisions of radically different origin, but with an indefinite boundary: I. the higher western portion, known as the Piedmont Plateau and underlain by very old rocks which have passed through many changes of structure and position; 2. the Coastal Plain, formed of numerous layers of unconsolidated sediments, sand, gravel and loam, which lie almost as originally deposited.

Accordingly, the geologic formations of the Washington district fall into two classes: first, the ancient and highly crystalline rocks; and secondly, the unconsolidated beds of the Coastal Plain. The former occur chiefly to the northwest and southwest of Washington; the latter lie to the south and east. The greater part of the city proper is built upon these unsolidified beds.

The Archaean Rocks. The principal varieties of rock found in or near the District of Columbia are as follows: 1. Carolina Gneiss, occurring northwest of Washington, where it may be seen along the gorges of the Potomac. It consists of alternate layers of gneiss and schist, varying from dark bluish-gray, when newly exposed, to green and yellowish-gray when weathered. 2. Granite Gneiss, of which there occurs a large irregular belt between Georgetown and Falls Church. This rock is similar in coloring to the Carolina gneiss, but it has a fine and uniform texture. It is the result of metamorphism of original granite. Complete disintegration of granite gneiss produces a stiff red clay. Fine specimens of this process may be seen in the deep road cuts between Washington and Chevy Chase (p. 12). 3. Diorite and Diorite Gneiss. The largest area in which this rock occurs extends N. and S. through Cabin John (p. 15); the second largest stretches N. from Georgetown. It is an igneous rock of massive texture, of a greenish-gray shading to black, the green being more pronounced in proportion to the amount of hornblende it contains. fact that it cuts through the Carolina and granite gneiss shows it to be the youngest formation of the three. 4. Gabbro and Metagabbro. Gabbro is a massive rock shading from dark gray to black. The largest area in which it is found is northeast of Cabin John, where metagabbro (from dark olive to a lighter green) also occurs. 5. Granite. Three different kinds are distinguished in the Washington district: a. the granite occurring in the beds of granite gneiess; b. a series of granite dikes that cut into the beds of Carolina gneiss. This granite is composed almost wholly of quartz and feldspar and is of a very light gray tone, weathering almost to white; c. two exposed belts in the basin of Rock Creek and the quarries on Broad Branch. This is a coarse aggregate of quartz and orthoclase feldspar, with plagioclase and biotite.

The

Coastal Plain Formations. These are locally of far more importance and interest than the Archaean rock formations above treated, because they form more than three-quarters of the area of Washington, inclusive of much of the surrounding territory. One important fact should be noted: that in the geology of this region the strata from the Archaean down to the close of the Mesozoic period are lacking. There are no traces of Permian, Triassic or Jurassic remains. The unsolidified Cretaceous beds rest directly upon the Archaean rock. Geologists distinguish nine distinct layers of these unsolidified deposits, separated, with one exception, by long periods of erosion. The separate layers are not of uniform extent, and nowhere do all nine occur superimposed; indeed, as will presently be shown, a large portion of the older city rests upon only two layers of deposit with the underlying Archaean rock. Yet all nine formations occur

within the District and exposures of them may be seen with comparatively little trouble.

It

De

ft.

1. Potomac formation (Early Cretaceous). This consists of clays and sand occurring separately and in a proportions of mixture. occupies the surface over a large part of the Washington district. In the terraces along the Potomac, it is overlaid by the Later Columbia formation (see below), and in the high terraces W. of Alexandria and the north portion of Washington by earlier members of that formation. To the E. it passes beneath the later Cretaceous and Neocene formations. It lies directly on Archaean rock; thickness, 0 to 650 feet. It overlies the greater part of the N. W. region beyond Florida Avenue. 2. Matawan (later Cretaceous). These are deposits of black argillaceous, carbonaceous sands and contain abundant molluscan fossils. There are excellent exposures in road icfu tis from Buena Vista, to the R. R. cut at Collington, and on the road from Good Hope to Twining (p. 413). 3. Monmouth formation (later Cretaceous). Brown sands, varying in thickness from 0 to 25 ft. Found in a small area near Collington, N. E. of Washington. 4. Pamunky formation (Early Eocene). Sands and marls of a bluish or greenish black. posits varying from o to 120 ft. in depth are found over a wide area E. of Washington where they are for the most part overlaid by Chesapeake or Lafayette formations. 5. Chesapeake formation (Miocene). Fine buff sands, clays and diatonaceous deposits, from o to 80 ft. in depth. Most of its area is overlaid by Lafayette formation. It occupies the greater part of the high plateau S. of Washington. Small masses underlaid the Lafayette gravels at Soldiers' Park (p. 432), and between Georgetown and Tenleytown. Good exposures occur in the road cuts halt a mile north-northwest of the Naval Observatory (p. 442) and in the road cuts about Upper Marlboro. 6. Lafayette formation (Pliocene?). Gravels, sands and loams on an extensive plain 20 to 30 in thickness. It covers the high, wide plains S. E. of Washington and caps the elevated area at the Soldiers' Home, and the ridge extending from W. of Georgetown to Tenleytown. The deposit is mainly quartzite gravel and loams, but contains some boulders. 7. Earlier Columbia formation (early Pleistocene). This is a deposit of gravels and loams found on the higher terraces, with an almost uniform thickness of 20 ft. Occurs along the terraces of the Potomac, Rock Creek, Anacostia and Patuxant Valleys. The most extensive deposits are W. of Alexandria and in Mount Pleasant (p. 13), and adjoining upper portions of the city of Washington. In the N. portion of the city and up the valley of Rock Creek these formations have an average altitude of almost 100 ft. The most extensive exposures are at the head of 16th St., in the upper part of the hollow S. of Anacostia, along Fort Foote Road and in old gravel pits on the Southern R. R., E. of Springfield station. 8. Later Columbia formation (early Pleistocene). These deposits occur in the lower terraces of the Potomac and its larger branches. About the city of Washington the more extensive Columbia terrace levels are respectively 40 and 90 ft.; the Capitol stands upon the western edge of a prominent outlier of the 90-foot terrace. This formation consists of a. a lower series of gravel, containing a heterogeneous mixture of pebbles, boulders, and irregular masses of crystalline rocks packed in brown sand and grading up into: b, a brown or buff massive loam. The finest exposures are in the street and R. R. cuts in the E. and N. W. sections of the city. See especially Pennsylvania Ave, extended, E. of the Anacostia River. Thickness, 25 ft. 9. Post-Columbia formation (Recent Pleistocene). This formation occurs mainly below tide water. To the S. and W. of the Mall a large area has been filled in from this alluvial deposit in the river bed, part of which constitutes Potomac Park (p. 352).

The city of Washington has a unique history among the capitals of the modern world. Unlike other cities, it is not the result of a slow growth and development from some original modest village, but like Queen Dido's fabled Carthage, a bold creation with its first stately government buildings rising spectacularly in the midst of forests, swamps and unploughed fields. In the years immediately following the Revolutionary war, the United States had no permanent Capital. It was not until 1783 that the idea of creating a separate national district in which to erect a central seat of government was first suggested, as a consequence of a serious riot in Philadelphia. A band of mutinous soldiers of the American army entered the city on June 20th of that year, marched to where the Continental Congress then held its sessions, and with threats of violence demanded arrears of pay. The pacific guardians of the Quaker city professed themselves unable to cope with the situation, and Congress was obliged to retreat to Princeton, N. J. This insolent treatment was felt deeply by the members and they agreed that the seat of government should be removed to some spot beyond danger of a repetition of the occurrence. Four months later the first public proposal to acquire territory for a National Capital was heard in Congress in the form of a notion introduced by Elbridge Gerry of Mass., recommending the Potomac region, near Georgetown, as one of the sites worth considering.

This resolution was carried on Oct. 7th, but subsequently amended, and later repealed in April, 1784. For four years the plan remained practically in abeyance through opposition due to sectional jealousy. In Oct., 1784, Congress appointed Commissioners authorized to lay out a District on the Delaware; and in Jan., 1785, similar ineffectual efforts were made to locate the District on the Potomac. The first decisive step was taken when the authority to acquire land for a Federal City was embodied in the Constitution of the United States (adopted in Sept., 1787), article 1, sec. 8, clause 16, which gives power to Congress to "exercise exclusive legislation in all cases whatsoever, over such district, not exceeding ten miles square, as may, by cession of particular states and the acceptance of Congress, become the seat of the Government of the United States." The above clause in the Constitution fixed definitely the size of the new District. Appreciating the advantage of having the Capital within its limits, Maryland,