MSRA Webinar Series - Hidden Legacies - Investigating Pre-Colonial Stream Corridors in the Mid-Atlantic Coastal Plain feat. Matthew J. Cashman, Ph.D.
MSRA is excited to continue our series of webinars featuring leading industry researchers and partners, as we strive to offer opportunities for discussion and promote advancement of the stream restoration science. Visit our website and social media channels for upcoming webinars.
Continuing Education Credits will be offered for the MSRA Webinar Series!
We hope you will join us:
When: Wednesday September 23rd, 2026
Time: 12:00 p.m. - 1:00 p.m.
Where: GoToWebinar
Following your registration, and prior to the event, you will receive a webinar link from GoToWebinar on the morning of the webinar which will give you access to the webinar.
Will you be attending?
Register Today! Registration will Close at 3pm the Day Before the Webinar.
EVENT DETAILS:
Cost: Free for members, $10 for non-members
Presentation Abstract: Within the Mid-Atlantic United States, widespread landscape disturbance during European colonization resulted in erosion and subsequent storage of legacy sediments within river valleys and floodplains, altering their form, function, and flora. Previous studies of precolonial river corridors have influenced river restoration designs and targets throughout the region, but the generalizability of these studies into other physiographic settings, such as the Coastal Plain, is unknown. Therefore, our study investigated the physical form and riparian vegetation of precolonial stream corridors located within the Coastal Plain of Anne Arundel County, Maryland, documenting changes from pre- to colonial and postcolonial time periods. Our study provides evidence of buried, precolonial riparian ecosystems with dates ranging between 750 years to 8000 years Before Present. These valley bottom ecosystems were likely a dynamic patch mosaic, largely dominated by dense Alnus (alder) scrub swamps with variable Poaceae (grass) and Cyperaceae (sedge) dominated meadows and both multi-threaded and single-threaded channel forms. These precolonial floodplains are buried by vast amounts of legacy sediment to the extent that pre-colonial sediments are largely not exposed in the modern valley bottom. Notably, the Coastal Plain precolonial corridors investigated in this study contrast to studies in the Piedmont physiographic region with precolonial sediments exposed in streambanks and with precolonial ecosystems described as herbaceous stream-wetlands. Our findings provide critical historical context as to the magnitude of alteration for modern stream channels and suggest an alternative precolonial ecosystem which can be used to inform restoration designs, management targets, and reestablishment of channel functional processes in areas of the Mid-Atlantic Coastal Plain.
Presenter Abstract: Matthew is a Physical Scientist with the USGS Water Mission Area. His expertise focuses on the interaction of surface water, water quality, and geomorphology on aquatic ecology and habitats. His work involves conducting integrated water availability and ecological assessments at national and regional scales.
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