Qfe
Upper level fluvial and estuarine deposits (Pleistocene)
Kps
Potomac Formation (Lower Cretaceous) Sand-dominated lithofacies
Ttu
Highest level upland terrace deposits (Tertiary)
Qa
Alluvium (Holocene)
Kpc
Potomac Formation (Lower Cretaceous) Clay-dominated lithofacies
QTt
Terrace deposits, upper level (Pleistocene and Tertiary)
Qd
Debris (Holocene and Pleistocene)
Qt
Terrace deposit, low level (Holocene and Pleistocene)
Tt
Terrace deposits (Tertiary)
dgf
Disturbed ground and artificial fill
Qc
Colluvium (Holocene and Pleistocene)
Tc
Calvert Formation (middle Miocene)
Ql
Landslide (Holocene and Pleistocene)
Qte
Low level fluvial and estuarine deposits (Pleistocene)
Km
Monmouth Formation (upper Cretaceous)
TKb
Brightseat Formation and Monmouth Group, undivided (lower Paleocene and upper Cretaceous)
Ta
Aquia Formation (upper Paleocene)
Kp
Potomac Formation (Upper and Lower Cretaceous)
Tyb
Yorktown Formation (Pliocene) and Bacons Castle Formation (upper Pliocene)
Ks
Severn Formation (upper Cretaceous)
Tm
Marlboro Clay (lower Eocene and upper Paleocene)
Tn
Nanjemoy Formation (Lower Eocene)