A Natural Resource Management Guide for the County of Morris A ...

Table Five - Hydrogeologic Characteristics of Glacial Deposits
DEPOSITS LOCATION COMPOSITION CHARACTERISTICS
STRATIFIED DRIFT
deltaic & lacustrine glacial lakes stratified sands & gravels very productive if thick unit
fan sediments
fluvial sediments deposited by meltwater stratified sands & gravels very productive if thick unit
in alluvial plains, or in
streambed
lake-bottom glacial lakes stratified clay, silt, and can act like semi-confining
fine-grained sand
unit
till scattered non-stratified & non-sorted minor aquifer or semimaterial;
silt, sand, gravel & boulders
confining unit
morainal along ice margins till minor aquifer or semiconfining
unit
Source: NJ Geological Report Series 34, Ground-Water-Withdrawal and Water Level Data for the Central Passaic River
Basin, New Jersey, 1898-1990, 1994.
Deltaic and lacustrine fan, fluvial, and lake-bottom sediments can be grouped together as stratified drift.
Deposited by glacial meltwater, stratified drift is more uniform and better sorted than tills, which were
deposited directly by the glacier. Coarse-grained, well sorted, saturated stratified drift is often associated with
highly productivity aquifers.
Till is present as both terminal and ground moraine. The terminal morainic deposits, although moderately
permeable, are of such a thickness as to yield significant amounts of water. The ground moraine is not nearly
as productive.
Near the glacier, sediments deposited from meltwater are commonly interlayered with till and are highly
variable both vertically and horizontally. Farther from the glacier, sediments are more uniform.
Poorly sorted sands and gravels, which have fine particles filling spaces between larger grains, may yield only
small quantities of ground water.
Slow moving meltwater deposited fine-grained sand, silt, and clay in lakes and ponds. Thick deposits often
act as confining layers to permeable water-bearing zones.
Postglacial materials consisting mainly of sand, gravel, silt, mud, and peat, often act as a semiconfining unit.
Buried Valleys
Preglacial and glacially deepened river valleys became filled with glacial sediments. These buried valleys have
been the subject of investigation because of their excellent water-bearing capabilities, particularlywhere filled
A Natural Resource Management Guide
for the County of Morris 57