|Maryland Geological Survey||Maryland's Geologic Features|
|A Geologic Walking Tour of Building Stones of Downtown Baltimore, Maryland||contact: Dale Shelton (email@example.com)|
|MGS Home | Walking Tour Home Page | Pamphlet Home | Online Publications | The List of Publications | Publications Office ||
STOP 5: MERCANTILE TRUST & DEPOSIT COMPANY BUILDING - 222 Redwood Street
Continue walking east along Redwood Street, crossing Calvert Street, to Stop 5. This dark red brick building, located at the northeast corner of Calvert and Redwood Streets, was constructed in 1885-1886 (Figure 5a).
The building has extensive trim made of Seneca Red sandstone. The sandstone is of Late Triassic age, about 210 to 230 million years old, and was quarried in either Montgomery or Frederick County, Maryland. This is the first sandstone encountered on the tour (Figure 5b). It is a sedimentary rock formed by the cementation of sand-sized grains of quartz (silica). Sandstones can usually be recognized by their sandpaper feel. The chief minerals in this rock are quartz, feldspar (microcline and plagioclase), and white mica (muscovite). The red color is largely due to iron oxide in the rock, mainly in the cementing material.
Since construction of the Mercantile Trust & Deposit Company building, however, weathering has had an effect on the building stone. Weathering is obvious on the stairs where spalling (flaking) is occurring.
An interesting architectural design for the time was the placement of spy steps (Dorsey and Dilts, 1981) in the front of the building. This would allow police officers to step up and peer into the bank while on patrol (Figure 5c). A brass ring at shoulder level was used to balance them on the step.
Seneca sandstone was a popular building stone in Baltimore and Washington, D.C. due to its accessibility and ease of transport. The sandstone was also popular because it is easy to cut and carve for decorative stone when first quarried, but then hardens over time. Seneca Red sandstone was used in the building of the original Smithsonian Institution (castle) building in Washington D.C. (constructed between 1848 and 1859) (Merrill and Matthews, 1989).
Trust & Deposit Company Building
5a: Front of the Mercantile Trust & Deposit
Company building (Stop 5).
This pamphlet was prepared by
Sherry McCann-Murray, with contributions and photography by the Environmental
Geology and Mineral Resources Program of the Maryland Geological Survey.
Adapted for the Internet from Educational Series No. 10. For more information see Building Stones of Maryland .
Compiled by the Maryland Geological Survey, 2300 St. Paul Street, Baltimore, MD 21218
This electronic version of "A Brief Description of the Geology of Maryland " was prepared by Bob Conkwright, Division of Coastal and Estuarine Geology, Maryland Geological Survey. Please send comments on this page to Dale Shelton (firstname.lastname@example.org)
State of Maryland
Department of Natural Resources, Resource Assessment Service