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Open-File Report 2004–1434
By Beth M. Wrege and Philip S. Jen
Strat-7
Map showing location of Strat-7 well
Lithologic log for Strat-7 test hole
Selected borehole geophysical logs collected in Strat-7 test hole
Strat-7 monitoring-well construction report
Periodic water levels in Strat-7 monitoring well
Hydrograph showing ground-water levels in Strat-7 monitoring well, September 2000–May 2002
Figure 31. Location of Strat-7 well, U.S. Marine Corps Air Station, Cherry Point, North Carolina.
| Depth below land surface (in feet) | Description (compiled by C.C. Daniel, III) |
|---|---|
| 0.0 – 0.9 | "A" horizon; soil zone gray, very fine sand, silty minor clay, roots. |
| 0.9 – 4.0 | Grayish-tan silty SAND, very fine sand. |
| 4.0 –5.5 | Orange, very fine SAND, silty, some clay. |
| 5.5 – 7.5 | Orange CLAY. |
| 7.5 – 11.0 | Yellowish-orange very fine SAND, silty, some thin clay disseminated through interval—thin sand layers (0.1 ft) with little clay color 5Y8/4. |
| 11.0 – 17.3 | SAND, well sorted, subrounded, frosted yellowish-gray sand, very fine. |
| 17.3 – 17.7 | CLAY. |
| 17.7 – 19.6 | Yellowish-gray SAND, very fine. |
| 19.6 – 21.5 | Grayish-orange CLAY. |
| 21.5 – 27.5 | Sandy CLAY with thin storm sands, heavy mineral lenses, grayish-yellow 5Y8/4 to pale yellowish-orange 10YR8/6. |
| 27.5 – 28.8 | Silty sand, clay 10YR6/6. |
| 28.8 – 30.0 | Silty clay, light olive-gray 5Y6/1. |
| 30.0 – 32.0 | Sandy CLAY—coarse, poorly sorted sand, fraction small pebbles 2–12 mm, well rounded. |
| 32.0 – 44.6 | SAND—coarse sand, moderately sorted, well rounded, frosted. |
| 44.6 – 60.5 | Fine to very fine SAND with some silt and clay. Sand angular to subrounded. Light olive-gray 5Y5/2. Sparse, widely scattered phosphate and quartz pebbles, 1-to 6-mm long dimension. Phosphate and quartz pebbles below 60 ft increase in size and abundance. |
| 60.5 –64.0 | 62.0–64.0 ft, quartz pebbles to 1 cm, phosphate pebbles to 2 cm. |
| 64.0 – 65.2 | Carbonate lag gravel, shell hash, with quartz and phosphate up to 3 mm. |
| 65.2 – 68.3 | Fossiliferous carbonate, light gray N7. |
| 68.3 – 71.5 | Sandy, silty, shell hash with scattered phosphate. |
| 71.5 – 73.4 | CLAY. |
| 73.4 – 86.2 | SAND with a few clay lenses, a few widely scattered quartz pebbles, well rounded, 3–5 mm. Fine to very fine sand, angular to subrounded scattered phosphate, fine to very fine, 1–2%. |
| 86.2 – 90.0 | Clayey, silty SAND. |
| 90.0 – 93.5 | Sandy CLAY with clay rip-up clasts, light gray N7 to very light gray N8 with no sand, slick when wet. |
| 93.5 – 100.3 | Silty, sandy CLAY to silty clayey SAND with shell fragments, chalky thin-walled bivalves. A few phosphate pebbles 2–3 mm, medium light gray N6 to medium greenish-gray, very fine sand fraction. |
| 100.3 – 102.5 | Silty, yellowish greenish-gray CLAY. |
| 102.5 – 124.5 | Fossiliferous sandy CLAY with abundant shell hash, lag gravel zones. 102–105, chert and chert fragments. 115–115.6, moldic, limestone, clay, yellowish-gray 5Y7/2. 123.9–124.5, sand content increases, contains shell fragments; interval has increased quartz and phosphate well-rounded pebbles 4–8 mm in diameter. |
| 124.5 – 134.7 | SAND, well sorted, fine; 1% phosphate of similar size, scattered phosphate pebbles 2–4 mm, scattered shell fragments subangular to rounded, partially frosted. 10YR7/1 light gray. |
| 134.7 – 154.8 | Fossiliferous CLAY, sandy, contains large shell fragments <2 inches in diameter of core contains chert nodules, some with chalky coating. Light greenish-gray 5G7/1. Sandy fraction decreases upward, size decreases. 153–154.8, shell hash with quartz pebbles, phosphate nodules, quartz and phosphate 3–9 mm, sandy-clay matrix, large shell fragments. |
| 154.8 – 198.0 | LIMESTONE, carbonate – interlayered sequence of porous calcarenite moldic limestone and friable to very friable moldic limestone, also includes lag gravel of carbonate fragments. Rare pieces of mother-of-pearl and chalky shells remain at places in the section. Sand in section is fine to medium, well rounded, and frosted. Minor phosphate mixed with the sand. Grayish-tan-buff color, may have some silt-clay in matrix. |
| 198.0 – 210.8 | LIMESTONE, "dirty" moldic limestone at top, gray 5Y7/1. Moldic limestone – "clean," light tan yellowish-gray 5Y8/1. Large voids up to 1.5–2 cm. "Dirty" moldic limestone at base of interval 5Y7/1. |
| 210.8 – 212.0 | LIMESTONE, "lag gravel" limestone fragments. |
| 212.0 – 214.0 | LIMESTONE, calcarenite – no megafossils. |
| 214.0 – 214.5 | LIMESTONE, "lag gravel" limestone fragments mixed with calcarenite (shell hash, plates?). |
| 214.5 – 257.5 | LIMESTONE, calcarenite – no megafossils. Small limestone fragments, plates? Small shells and shell fragments leached out 10YR8/1 very pale yellowish-gray. Friable to indurated/cemented sand. Sand is fine to medium, moderately well sorted, subangular to rounded, 1–2% phosphate sand-size grains. Scattered plates (carbonate/aragonite?). |
| 257.5 – 264.0 | LIMESTONE, calcarenite with shell, shells are chalky, appear to be bivalve shell fragments, aragonite (?); plates, 263–264. |
| 264.0 – 265.0 | LIMESTONE, moldic. |
Figure 32. Selected borehole geophysical logs collected in Strat-7 test hole, U.S. Marine Corps Air Station, Cherry
Point, North Carolina.
Figure 33. Strat-7 monitoring-well construction report, U.S. Marine Corps Air Station, Cherry Point, North Carolina.
| Date | Water level, in feet below land surface |
|---|---|
| 09-21-2000 | 17.33 |
| 10-05-2000 | 17.15 |
| 02-09-2001 | 17.60 |
| 05-03-2001 | 17.92 |
| 08-09-2001 | 18.74 |
| 03-29-2002 | 16.71 |
| 05-15-2002 | 18.23 |
Figure 34. Hydrograph of ground-water levels in Strat-7 monitoring well,
U.S. Marine Corps Air Station, Cherry Point, North Carolina, September 2000–
May 2002.
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