Photograph and description from the Maryland Historical Trust..
The Monocacy site is a large stratified site on the Potomac River floodplain. Near the river, nine vertical zones are easily discernible, comprising eleven feet of alternating sterile and culture-bearing strata. Away from the river, the site’s depth decreases with the disappearance or compacting of the various strata. The deepest cultural layer consists of dark soil containing rhyolite debitage, but lacking diagnostic artifacts.
Above this, separated by a sterile layer, is a stratum containing artifacts of four sequential phases which range from the Terminal Archaic to Early Woodland periods. Represented by Susquehanna Broadspear projectile points and steatite vessels, the earliest component is associated with the Susquehanna Soapstone tradition of the terminal Archaic period. Marcey Creek steatite-tempered pottery overlies and sometimes intermixes with this layer, indicating an early Early Woodland occupation.
Slightly above this but showing considerable overlap is a friable and grit-tempered pottery. Above this is quartz-tempered pottery. Separated from this stratum by another sterile layer is a Late Woodland layer composed of two components marked by two distinct pottery types: limestone-tempered and shell-tempered. The last prehistoric occupation of the Monocacy site and found at the top of this level is represented by quartz-tempered pottery of the Potomac Creek type. The topmost stratum of the site contained artifacts from the c. 1830s C&O Canal era and the 1860s Civil War period.
The Monocacy Archeological Site is one of the deepest known stratified sites in Maryland. The Marcey Creek component of the Monocacy site represents the earliest (950±95 B.C.) dated manifestation of pottery in the Potomac River valley and is one of the earliest dated appearances of pottery anywhere in the east.