The Aquia Creek sandstone, also 

called “freestone,” was a popular building material between 1790 and 1840. It 

was prized for construction because of 

the ease with which it could be carved 

and transported to building sites along 

the Potomac River. George Washington 

selected the Aquia Creek sandstone 

as the primary material for use in 

Government buildings. In 1791, and 

acting on the Government’s behalf, 

Pierre L’Enfant—the architect and engineer selected to design the new city of 

Washington, D.C.—purchased a quarry 

about 40 miles south of Washington along 

Aquia Creek in Stafford County, Virginia. 

(The peninsula on which the quarry is 

located subsequently became known as 

Government Island and today is a natural 

park preserve and archaeological site.) 

Stone from this quarry was used for the 

original portions of the President’s House 

(later known as the White House), some 

older portions of the U.S. Capitol building, 

the oldest portions of the U.S. Treasury 

building, and numerous other smaller 

structures around the city.

The Aquia Creek sandstone is of 

Early Cretaceous age (between 100 and 

140 million years old). It is composed primarily of sand and pebble-sized quartz and 

clay pellets and is cemented with silica. 

Unlike many other sandstones, its matrix 

is harder than its crystals, which gives it a 

quality of toughness without brittle hardness. In appearance, the coarse-grained 

stone is light gray or tan, and it is streaked 

or clouded with buff, yellow, or red colors 

that give it a warm tone.

Unfortunately, the Aquia Creek 

sandstone proved to have quality-related 

flaws, and it weathered poorly. After the 

burning of the White House and Capitol 

buildings by British troops in 1814, the 

walls made of Aquia Creek sandstone 

suffered cracking and pitting. Both buildings were whitewashed and later painted 

to mask the damage and help protect the 

stone from weathering. As the defects 

of the stone became apparent, its use for 

exteriors declined. One of the last major 

exterior uses of the stone was at the 

U.S. Capitol gatehouses and gateposts

(circa 1827). One of these gatehouses 

and three of the gateposts are located at 

15th Street and Constitution Avenue NW, 

and another gatehouse is located farther 

west at 17th Street NW.

Interior use of the Aquia Creek sandstone may also be seen in the U.S. Capitol, 

including in the walls and columns of the 

rooms adjoining the Rotunda and in the 

spiral staircase. It was also used in the 

Little Rotunda tobacco column colonnade in the Senate wing on the same floor, 

in the famous cornstalk columns in the 

Senate vestibule, and downstairs in the 

Doric sandstone columns of the crypt.

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2012–3044

April 2012 Printed on recycled paper

Famous Building Stones of Our Nation’s Capital

The buildings of our Nation’s Capital are constructed with rocks from quarries located throughout the United States and many 

distant lands. The earliest Government buildings, however, were constructed with stones from nearby sources because it was too 

difficult and expensive to move heavy materials such as stone any great distance without the aid of modern transportation methods, 

including large cargo ships, trains, and trucks. This Fact Sheet describes the source and appearance of three local stones commonly 

used in building Washington, D.C.

Aquia Creek Sandstone: White House, Capitol Building, and Gatehouses

U.S. Capitol gatepost

U.S. Capitol gatehouse

Aquia Creek sandstone

White House U.S. Capitol

Laura Corey, USGS Laura Corey, USGS Laura Corey, USGS
During the “brownstone era,” from 

about 1840 to about 1880, red Seneca 

sandstone was an extremely popular 

building stone in Washington. This stone 

of Triassic age (more than 200 million 

years old) crops out along the Potomac 

River in the Triassic lowlands from 

Seneca, Maryland, to just east of Point of 

Rocks, Md. Red Seneca sandstone ranges 

from reddish brown to a deep purplish 

brown. It is brightly colored when cut 

but darkens and hardens on exposure 

to air. Seneca sandstone is generally 

fine-grained and uniform, and it does not 

easily scale when exposed to weather.

Several quarries supplied this 

red sandstone to the city. The best 

known is located about 20 miles up the 

Potomac River on the Maryland shore in 

Montgomery County just west of Seneca 

Creek. The remains of the quarry where 

canal barges were loaded with stone for 

shipment up or down the canal may still 

be seen. The ruins of a quarry building 

that housed saws and machinery for finishing the stone stand nearby. (Note: This 

site is located on private land.)

The first important Government 

building to be constructed of this sandstone was the carved and turreted main 

building of the Smithsonian Institution 

(the Castle), which was built between 

1847 and 1857. The sandstone, when 

first quarried, was described as lilac gray; 

after years of oxidation, it is now a dark 

red. Seneca sandstone is also prominent on the floors and the Rotunda door 

frames in the U.S. Capitol.

Marble eventually replaced 

sandstone as the most popular building 

stone in Washington. Of particular 

note were the three different kinds of 

regionally metamorphosed marbles of 

late Precambrian to early Paleozoic 

age that were used in the construction 

of the Washington Monument. The 

first 152 feet of the monument, which 

was built between 1848 and 1854, is 

faced with marble from the quarry 

located at Texas, Md., just north of 

Baltimore in the Piedmont Province. 

Work stopped when funds ran out. 

When construction was about to resume 

in 1876, the builders discovered that 

the foundations were inadequate and 

that the monument was sinking and 

tilting. To straighten and stabilize the 

monument, wider subfoundations were 

constructed to a depth of nearly 37 feet. 

In 1879, work began again on the upward 

projection of the monument, and four 

courses, or rows, of white marble from 

Sheffield, Massachusetts, were laid 

above the Texas, Md., marble. Because 

of difficulties with timely delivery and 

quality control of the marble, however, 

the contract with the Sheffield quarry was 

annulled in 1880. The extensive upper 

part of the monument was then finished 

with marble from a quarry located north 

of Baltimore in Cockeysville, Md. The 

monument was completed in 1884, 

reaching a height of 555 feet and 5 inches.

The three kinds of marble used 

in the monument can be distinguished 

by their differences in color. The lower 

section is the white, coarse-grained, 

nearly pure calcium carbonate marble 

from the Texas, Md., quarry. The upper 

section is built of fine-grained marble 

from the Cockeysville, Md., quarry. The 

Cockeysville marble is a clear white 

stone with a few pale streaks or bands, 

and its higher magnesium content gives it 

a pale gray sheen. Both marbles contain 

veins and pockets of mica and pyrite, 

which can stain the marble if it is exposed 

to the elements. In between these two 

marbles are four rows of a pronounced 

white marble from the Sheffield, Mass., 

quarry.

This Fact Sheet is based on a more extensive 

U.S. Geological Survey publication, 

“Building Stones of Our Nation’s Capital,” 

at http://pubs.usgs.gov/gip/stones.

Seneca Sandstone: Smithsonian Institution Main Building (the Castle)

Smithsonian Castle

Seneca sandstone

Washington Monument

Cockeysville marble

Sheffield marble

Texas marble

Cockeysville marble from the Washington 

Monument showing damage caused by the 

August 2011 earthquake.

Cockeysville Marble: Washington Monument

For more information, contact:

U.S. Geological Survey

Office of Science Quality and Integrity

12201 Sunrise Valley Drive, MS 912

Reston, VA 20192

Web site: http://education.usgs.gov

National Park Service

Laura Corey, USGS