Geology topics

Research about Jones County, Onslow County, North Carolina

Source-linked reports with geographic coverage including Jones County, Onslow County, North Carolina.

2 recordsLinked to original sources

USGS1990

Hydrogeology of aquifers in Cretaceous and younger rocks in the vicinity of Onslow and southern Jones counties, North Carolina

Unconsolidated sediments in Onslow and Jones Counties, North Carolina overlie crystalline basement rocks and range in thickness from about 700 ft to more than 1,800 ft, thickening toward the east. This material is composed of permeable sand and limestone interlayered with relatively impermeable clay and silt beds. Sediments are divided into two groups: aquifers in Quaternary-, and Tertiary-aged rocks and aquifers in Cretaceous-aged rocks. Aquifers in the Cretaceous rocks provide most of the groundwater for public supplies and are the focus of this report. The aquifers in Cretaceous rocks are the Peedee, Black Creek, upper Cape Fear, and lower Cape Fear aquifers, which are composed of beds or groups of beds of sand and gravel. Each aquifer is overlain by a clay and silt bed, that impedes the flow of water between aquifers. The thickness of Cretaceous hydrogeologic units ranges from about 700 ft to more than 1, 300 ft. Hydrogeologic units are correlated using 60 geophysical logs and accompanying drillers ' logs along with water level and water quality data. Three hydrogeologic sections demonstrate the continuity of the aquifers and confining units, show water levels and chloride concentration in water from test intervals, and delineate where chloride concentration in water exceeds 250 mg/L within each aquifer. Maps of each aquifer in Cretaceous rocks show altitude of its top, thickness, sand percentage, and the transition from freshwater to saltwater. Maps of the confining units show thickness and sand percentage of each.

North Carolina↗

USGS1990

Ground-water pumpage and water-level declines in the Peedee and Black Creek aquifers in Onslow and Jones counties, North Carolina, 1900-86

Two aquifers in sediments of Cretaceous age, The Peedee and Black Creek aquifers, have become a major source of freshwater in Onslow and Jones Counties in North Carolina since about 1960. Prior to 1960, most water systems in this area withdrew water from younger sand or limestone beds that overlie the Peedee and Black Creek aquifers. Water-quality and economic considerations related to the treatment of water from these shallower aquifers led to increased use of the Peedee and Black Creek aquifers. Water withdrawals from the Black Creek and Peedee aquifers were about 10,000 gallons per day in 1933. By 1986, total withdrawals were about 7.8 million gallons per day, about 90 percent of which was supplied from the Black Creek aquifer. As a result of these withdrawals, ground-water levels have declined throughout Onslow and Jones Counties. The average rate of decline in static water levels in the Peedee aquifer is about 0.6 feet per year in central Jones County and about 1.4 feet per year in northern Onslow County. Rates of water level decline in the Black Creek aquifer average about 8.3 feet per year in Jones County to about 12 feet per year in northern Onslow County. Water levels in the Peedee aquifer have declined as much as 40 feet in Jones County and 80 feet in northern Onslow County since about 1900. During the same period, water levels in the Black Creek aquifer have declined as much as 120 and 160 feet in Jones and northern Onslow Counties, respectively.

North Carolina↗