Hydrologic Stratigraphy
Delaware's Hydrologic Stratigraphy
The following table displays the correlation of hydrologic units to geologic units recognized
by the Delaware Geological Survey in the Delaware Coastal Plain.
| Age |
Geologic Units |
Hydrologic Units |
| Holocene |
|
| Pleistocene |
Carolina Bay deposits
upland bog deposits
Cypress Swamp Fm.
Nanticoke deposits
Scotts Corners Fm.
Lynch Heights Fm. |
Columbia/ Unconfined/ Pleistocene aquifer - poor
to excellent yield, minor confining beds |
| Omar Fm. |
Confining unit over Columbia aquifer only in southeastern
Sussex County - minor poor aquifer |
| Columbia Fm. |
Columbia/ Unconfined/ Pleistocene aquifer
- poor to excellent yield, minor confining beds |
| Pliocene |
Beaverdam Fm. |
| Miocene |
Bethany Fm. |
Interbedded confining units and Pocomoke aquifer
- fair to excellent yield |
| Cat Hill Fm. |
Manokin aquifer - fair to excellent yield and
confining beds |
| St. Marys Fm. |
Confining beds - minor poor aquifer |
| Choptank Fm. |
Interbedded unnamed aquifers; fair to good yields,
and confining units
Milford aquifer - fair to good yield |
| Calvert Fm. |
Confining beds
|
| Frederica aquifer - fair to good yield |
| Confining beds |
| Federalsburg aquifer - fair to good yield |
| Confining beds |
| Cheswold aquifer - fair to excellent yield |
| Confining beds |
| Oligocene |
Glauconitic unit of Oligocene age |
|
| Eocene |
Glauconitic unit of late Eocene age |
| Piney Point Fm.
| Piney Point Aquifer - poor to excellent yield,
interbedded confining units |
Shark River Fm.
Deal Fm. |
Confining Beds |
| Manasquan Fm. |
Rancocas aquifer - fair to good yield,
interbedded confining units |
| Paleocene |
Vincentown Fm.
|
| Hornerstown Fm. |
Confining beds |
| Cretaceous |
Navesink Fm. |
| Mount Laurel Fm. |
Mount Laurel Aquifer - poor to good yield |
| Marshalltown Fm. |
Confining bed |
| Englishtown Fm. |
Englishtown Aquifer - fair to good yield |
| Merchantville Fm. |
Confining bed |
| Magothy Fm. |
Magothy Aquifer - fair to good yield |
| Potomac Fm. |
Potomac aquifers and confining units - fair to
excellent yields |
| Triassic and Jurassic |
Post-rift unconformity rocks (of Jurassic age)
Rift basin rocks (inferred)
|
|
| EXPLANATION: Aquifer Yield |
| poor <10 gpm |
fair 10 - 50-gpm |
good 50 - 500 gpm |
excellent >500 gpm |
| gpm = gallons per minute |