Surface and shallow subsurface sediment regime of the nearshore inner continental shelf, Nags Head and Wilmington areas, North Carolina / by Daniel R. Pearson.
| Author/creator | Pearson, Daniel R. author. |
| Other author | Riggs, Stanley R., degree supervisor. |
| Other author | East Carolina University. Department of Geology. |
| Format | Theses and dissertations |
| Production | 1979. |
| Description | v, 120 leaves : illustrations, maps ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | In order to characterize the sediments and geologic processes operating within the nearshore inner continental shelf off Dare and New Hanover Counties, North Carolina, 39 sample stations were occupied along 6 three nautical mile sample traverses run perpendicular to shore. The following samples and information were collected and analyzed from the nearshore shelf of the two study areas: 1) 43 surface samples, 2) 25 hand-core samples, 3) 32 vibracores, 4) approximately 100 nautical miles of seismic profiles, and 5) diver observations from each of the sample stations. The Nags Head nearshore inner continental shelf is characterized by a thin modern shoreface sediment wedge overlying an eroding sequence of Pleistocene sedimentary units. Distribution of the modern surface sediment is a direct function of the bottom topography, water depth, distance offshore, and the proximity of relict strata. In profile the Nags Head nearshore shelf is characterized by a steep shoreface, which planes out into a major topographic low trough which is oriented oblique to the shore. Seaward of the low trough is a major topographic high shoal complex. Each topographic environment has a distinct sedimentary facies type associated with it. Variations in each of these specific topographic-facies types may result from the presence of relict stratigraphic units. In contrast, the surface sediment distribution pattern on the Wilmington nearshore inner continental shelf is more complex. This complexity arises from the abundance and activities of benthic organisms and extensive exposures of Pleistocene and Tertiary sediment and rock strata on the Wilmington nearshore shelf. Thus, the resulting surface sediment distribution pattern is largely a function of the distribution and type of relict strata which is exposed and actively being eroded. In general, distinct sedimentary facies found on the Wilmington nearshore shelf are limited to facies corresponding to well defined topographic highs and topographic lows. Seaward of the lower shoreface the nearshore shelf of both areas consists of a thin veneer of modern sediments overlying relict strata. Thickness of the modern sediment sheet varies according to bottom topography, being thinnest or absent in the major topographic lows. Thus, some topographic lows are floored with relict strata. In addition, the topographic lows commonly serve as traps where thin deposits of lag gravels and modern muds accumulate. Black organic-rich muds were commonly observed in the topographic lows. These muds were found in topographic lows within water depths as shallow as 28 ft (8.5 m) located 0.2 nautical miles offshore. Topographic highs consist of actively mobile modern sands responding to wave induced bottom currents which are focused on the highs. The modern sediment sheet is thicker where the topographic highs are located. Major relict fluvial-estuarine channels occur in the subsurface on the nearshore continental shelf off both study areas. These channels are thought to be products of the ancestral Albemarle-Roanoke River system in Dare County and the ancestral Cape Fear River system in New Hanover County. |
| Local note | Joyner-"Presented to the graduate faculty of the Department of Geology ... in partial fulfillment of the requirements for the degree Master of Science in Geology." |
| General note | Presented to the Graduate Faculty of the Department of Geology |
| General note | Advisor: Stanley R. Riggs |
| Dissertation note | M.S. East Carolina University 1979 |
| Bibliography note | Includes bibliographical references (leaves 115-117). |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
Availability
| Library | Location | Call Number | Status | Item Actions |
|---|---|---|---|---|
| Joyner | University Archives | ASK AT SPECIAL COLLECTIONS DESK | ✔ Available | Request Material |
| Joyner | NC Stacks | GC383 .P42 1979 | ✔ Available | Place Hold |
| Electronic Resources | Access Content Online | ✔ Available |