Geomorphological processes and the development of the lower Saint John River human landscape

The nature of human interaction with the landscape, both past and future, is an essential question for both geology and archaeology. Landscape elements are controlled in large part by long-term temporal processes and are recorded in the thick sedimentary deposits found within the lower Saint John River valley, New Brunswick. A 67 m continuous core was recovered through drilling at Grand Lake Meadows, located at the junction of Grand Lake and the Saint John River, approximately 55 km south of Fredericton, New Brunswick. Sediment samples were collected from the core to identify stages of development of the marsh land area and surrounding environs since deglaciation. Analytical tests include particle size analysis and atterberg limit determination, loss-on-ignition, x-ray diffraction, and ion chromatography. Organic samples were also collected for radiocarbon dating, which allowed for the development of chronological control of changes in both the environmental and archaeological record. The Grand Lake Meadows is interpreted as having evolved through four phases of development. Phase one starts with deglaciation and continues to ~11,500 BP. Deglaciation began into a marine environment, which was undergoing desalinization due to pulses of fresh water from melting ice and retreating glaciers. Phase two began ∼11,500 BP and continued until 8000 BP at which time there was major isostatic readjustment in the region. It was during phase two that the stratified Ancestral Grand Lake was established. Phase three began ∼8000 BP and continued until 3000 BP. Phase three represents an increased northern contribution or' fresh water and the demise of Ancestral Grand Lake. The lower Saint John River valley consisted of a fluvial dominated fresh water system, which likely initiated the down-cutting of the Reversing Falls gorge at the coast. During phase four, ∼3000 BP to present, marine water breached the Reversing Falls allowing saline water to penetrate into the lower Saint John River valley. This breaching at the falls led to the development of the modern river valley and Grand Lake Meadows. This landscape reconstruction, which documented change in the sediment system, landscape morphology, depositional histories and chronology, examines possible linkages between geological events and human activity within the Grand Lake Meadows system.

• http://www.proquest.com/docview/843285664/abstract/D4A3FCE15C1F48FFPQ/1