H11F-0828
Hydro-climatological Impact of Century Long Drainage in Midwestern United States
Today's Corn Belt in the Midwest USA is located on an area which was largely wetlands 150 years ago. Compared to the pre-European settlement baseline, more than 85% of wetland area has been lost. Large scale artificial drainage activity, which peaked between 1900 and 1930, is primarily responsible for this decrease in wetland area. The consequences of wetland drainage have been characterized including diminished flood storage, changes in vegetation community composition, habitat loss, and changes in bio- geochemistry (e.g., carbon sink to carbon source). However, one potentially important impact, the effect of wetland loss on regional hydro-climatology (temperature and precipitation), has not been characterized. This study will: (a) present the history of artificial drainage in Midwest USA from 1860 to present, and (b) discuss the interaction between wetland drainage and the atmosphere using modeling experiments. Study area encompassing 8 states in Midwest USA (293 million acre) contains intensively drained states like Indiana and Ohio, as well as less drained states like Wisconsin and Missouri. Geospatial data sets of drainage acreages at county scale are based on US census reports from 1920 to 1980 and contemporary wetland data are based on remote sensing data. Interaction between wetland drainage and the atmosphere will be modeled using a coupled land surface and regional climate model.
H11F-0829
Holocene floodplain sedimentation in Central Europe and the impact of historic mining
In most parts of Europe, the Late Quaternary evolution of floodplain environments is the result of interactions between natural and human factors. Land-use changes, during the Neolithic, such as deforestation and the introduction of agriculture affected the stratigraphy of river sediments due to soil erosion on the slopes and alluvial deposition of fine-grained sediments in the floodplains. Beside agriculture mining must be also considered as an important factor controlling the Late Holocene floodplain evolution. Prehistoric and historic metal mining activities caused landscape degradation, such as vegetation clearance which increased the rate of soil erosion especially via hillslope gullying. During the Late Middle Ages, East Bavaria, Germany and the Vils River Valley in particular were one of the leading regions for the iron industry in Central Europe. Two hundred ironworks used 378 000 m3 of wood per annum allowing the production of 9000 tons of iron during the "golden age" of mining in the 15th century. Since the late 19th century the role of the iron industry in East Bavaria has decreased rapidly. The intensive historic mining activities on the Vils River floodplain should have affected the river structure as well as the fluvial dynamics, in particular via the construction of ironworks and associated weirs. Further floodplain sedimentation is thought to have been influenced by the mining-induced soil erosion occurring in the catchment and primary on the slopes. The nature and extent of these changes have not been investigated to date. Analysis of 288 percussion drillings with depths of up to 7 m and a 120 m long excavator section provide new and detailed information on the Late Pleistocene to Late Holocene floodplain evolution. The generalised sequence of the Vils River floodplain is built up of five units representing facies of different genesis (rock/saprolite, gravel, sand, loam, peat) which are identified by physical, chemical and mineralogical parameters (grain size, clast shape and content, TOC, bulk mineralogy). Along the 87 km length of the valley, different units/facies are found at the Upper Vils River (UVR 1 – 5) and at the Lower Vils River (LVR 1 – 4b). In both river sections fine grained material (flood loam) form the major part (up to 4 m) of the alluvial sequence. 29 age determinations (24 14C, 4 IRSL, 1 tree-ring analysis) show increasing accumulation of flood loam in the last millennium. The data correlate with the beginning of mining at the Vils River and hence suggest a causal connection by mining activities in the catchment – both on the slopes and in the floodplain – with intense deposition of flood loams. By presenting these new data we also want to contribute to the evolving discussion of human impact on natural streams. Especially in the United States the decade-old "legacy sediment debate" recently was re- incited by Walter and Merritts (2008) who concluded that "fluvial aggregation and degradation in the eastern United States were caused by human induced base-level changes" from several processes initiated mainly by 17th to 19th century milldam construction. The critical remarks of Bain et al. (2008) and Wilcock (2008) demonstrate that probably more evidence is needed to justify the broad applications of findings in alluvial landscapes and that the comparison with well studied floodplains in Central Europe may be a key to answer open questions in this debate.
H11F-0830
Colonial Era Impoundment of the Northeastern United States: Beaver Trapping and Low- head Dam Construction
Hydrologic systems of the northeastern United States were transformed by European settler activities. The colonial economy shifted engineered water structures from beaver dams to human dams built for power generation. While the geomorphic effects of human-constructed dams have recently garnered considerable attention, few studies have investigated how intensive trapping for the fur trade, the near extermination of the Northeast beaver population, and the consequent loss of beaver ponds altered the regional water balance. Although reconstructions of colonial beaver populations have been made, none link the decline in beavers to its hydrologic impact. Beaver population models based on pre-colonial population estimates, historic harvest rates, and current-day population dynamics were used to simulate the corresponding decrease in pond numbers over time. Beaver populations declined dramatically during the seventeenth century, with harvest rates estimated at 2,000-10,000 beavers per year, resulting in expatriation in some sub-regions by the early 1700s. Using contemporary estimates of beaver pond volumes, the calculated loss in pond storage between 1600 and 1840 was approximately 17 million cubic meters of water and sediment, considerably larger than estimated storage gains from dam construction in the same period, suggesting that beaver eradication was a major driver of hydrologic change during the colonial era.
H11F-0831
Synthesizing US Colonial Climate: Available Data and a "Proxy Adjustment" Method
Climate and its variability is a primary driver of hydrologic systems. A paucity of instrumental data makes reconstructing seventeenth- and eighteenth-century climatic conditions along the Northeast corridor difficult, yet this information is necessary if we are to understand the conditions, changes and interactions society had with hydrosystems during this first period of permanent European settlement. For this period (approx. 1600- 1800) there are instrumental records for some regions such as annual temperature and precipitation data for Philadelphia beginning in 1738; Cambridge, Mass., from 1747-1776; and temperature for New Haven, Conn., from 1780 to 1800. There are also paleorecords, including tree-rings analyses and sediment core examinations of pollen and overwash deposits, and historical accounts of extreme weather events. Our analyses of these data show that correlating even the available data is less than straightforward. To produce a "best track" climate record, we introduce a new method of "paleoadjustment" as a means to characterize climate statistical properties as opposed to a strict reconstruction. Combining the instrumented record with the paleorecord, we estimated two sets of climate forcings to use in colonial hydrology study. The first utilized a recent instrumented record (1817-1917) from Baltimore, Md, statistically adjusted in 20-year windows to match trends in the paleorecords and anecdotal evidence from the Middle Colonies and Chesapeake Bay region. The second was a regression reconstruction for New England using climate indices developed from journal records and the Cambridge, Mass., instrumental record. The two climate reconstructions were used to compute the annual potential water yield over the 200-year period of interest. A comparison of these results allowed us to make preliminary conclusions regarding the effect of climate on hydrology during the colonial period. We contend that an understanding of historical hydrology will improve our ability to predict and react to changes in global water resources.
H11F-0832
Dam Dynamics in the Colonial Northeast and Chesapeake: Hydrologic Implications
Recent work has highlighted the widespread presence of low-head dams for power generation during the 19th century. However, this work largely depends on census numbers tabulated in the mid-1800s, over 200 years after European activity began in North America. In order to compare the hydrologic implications of colonial era low-head dam construction with the impacts of other simultaneous processes (e.g., expatriation of the beaver or forest clearance), we have compiled historical data on mills to reconstruct the temporal and spatial dynamics of low-head dam construction in the colonial northeastern United States (i.e., Virginia to Maine). This reconstruction, combined with the results of related work on beaver pond dynamics and deforestation, provides several insights into the distribution and impacts of human impoundments during this period. While the resulting hydrologic changes are large, the addition of human dams to the system seems to be minimally offset and less important than changes arising from the expatriation of the beaver or the removal of trees during this early period. In addition, the spatial patterns of dam construction are complex, making prediction of hydrologic and associated responses more difficult to predict.
H11F-0833
Estimating Regional Water Residence Time Changes in the Colonial Northeast United States
The Northeast United States experienced a fundamental change following colonization by Europeans. During the period from 1600 to 1800 forests were cleared, agricultural lands were expanded, beavers were hunted to near-extinction, wetlands were drained or filled, and cities were built. Such activities had important implications for the stocks of water on and the fluxes of water through that landscape. We have made an early attempt to quantify the changed water stocks and fluxes in the Northeast during this time period using historical information and simple analyses. Simple calculations and estimates of stock and flux uncertainty were used to compute the distribution of land surface water residence times at the beginning and ending of the Colonial Era. Our estimates show that humans shifted water residence towards shorter times, which would have important implications for geomorphology, biogeochemistry, and how humans responded to their alteration of the hydrologic cycle.
H11F-0834 INVITED
Evolution of Hydro-systems: The 500-Year Challenge
We take as our starting point the tenet that humans are rapidly embedding themselves into the basic character of the water cycle, through a myriad of processes including direct water abstraction and flow diversion, land cover change, pollution, destruction of aquatic biodiversity, and climate change as part of a broad transformation and co-option of natural ecosystem services by society. Given this modern-day reality, it is now difficult to view hydrology as a purely nature-dominated science. Hydraulic engineering, land use and land cover change, and protecting society from the vagaries of climate all figure prominently in any discussion of the state and dynamics of the contemporary water cycle. Traditional initial and boundary conditions for hydrologic problems are no longer applicable in heavily populated or economically developing parts of the world. Initial and boundary conditions are instead dependent on a myriad of legacy effects associated with human decision-making, economics, governance, politics, culture, and even religion that may have taken place in times long gone and in settings far upstream of a particular downstream area of interest. Reconstructing time series of human-water cycle interactions and establishing their connectivity over time and space can afford insight into the co-evolution of biogeophysical and social dynamics with hydrologic cycle state, its variability, and trajectories. It also provides an important opportunity to break down traditional disciplinary boundaries associated with water and environmental studies more generally. The Northeast Corridor of the U.S. provides an ideal setting for testing these notions, and a millennial-scale perspective affords us the opportunity to quantify and assess the evolution of human-water interactions from the time of first European settlement into the 21st century. Such an assessment provides the necessary benchmark against which we can improve our understanding of the modern evolution of highly engineered water and land systems, and gives us a perspective on unfolding strategic water issues into the remainder of this century. This talk will present an overview of the rationale, modes of execution, and early results emerging from an NSF-funded hydrologic synthesis prototype effort.
H11F-0835
Reconstructing Colonial Land Cover Changes Across the Northeastern United States to Understand Hydrologic Changes
Land cover change is one of the most important drivers of hydrologic change. While we understand the North American landscape was substantially altered during the colonial period (1600-1800), the highly variable spatial and temporal dynamics of land cover change have not been yet resolved. Past land cover changes have important implications for the hydrologic history of the region and impart legacy effects on contemporary hydrologic systems. Before European arrival, the northern portion of the region was predominantly a game economy with increasing predominance of subsistence agriculture as one moved south. Upon arrival of Europeans, the region was transformed to a resource extraction economy, predominantly export oriented logging and agriculture production. Several authors have reconstructed historical land use change history at a variety of scales (county, watershed, and globe) based on paleo signatures in sediment cores, historical anecdotes, export data, and population based model. However, fewer integrated efforts utilize these historical land cover reconstructions to inform our understanding of hydrologic change, particularly at the regional scale. Therefore, we synthesize a variety of approaches to reconstruct a regionally coherent/consistent picture of land cover change in the northeast from 1600 to 1800. Our study region is divided into two major hydrological sub-regions based on glaciation history and contemporary climate gradients: the New England region and the Chesapeake Bay regions. We try to clarify uncertainty of each study and difference between them due to diverse research methods and scales. Using a meta-analysis approach and geospatial representation we have hypothesized that intensive land cover changes along coastal lines and navigable river reaches had a significant impact on the regional hydrology.
H11F-0836
Effects of historic land-use change on soil erosion in the Great Lakes region
Historic land-use change has affected hydrology in the Great Lakes region as once dominant forests have been converted to agricultural land in many areas. This change also impacts soil erosion potential. The effect of historic land-use change on soil erosion was evaluated for three Great Lakes states (Minnesota, Wisconsin and Michigan) using a newly developed coupled large-scale hydrology and soil erosion modeling scheme. The southwestern part of the region was converted from prairie grasslands to croplands, the central part was deforested for agriculture and the northern part converted from evergreen to deciduous forest. On an average annual basis, soil erosion in the southwest increased up to 30 t / ha × yr despite decreases in annual surface runoff and soil moisture. Land-use change from forests to cropland generated more soil erosion than conversion from grassland to cropland, however, changes in soil erosion were not only related to vegetation cover. Significant controls on erosion included precipitation intensity, which was in part affected by the presence of a vegetation canopy, and slope steepness. The highest simulated soil losses were concentrated in southern part of the domain along the borders of Minnesota and Wisconsin. This area is dominated by the Mississippi River valley where there is an increase in slope variability and the frequency of steep slopes. Erosion was minimal when natural vegetation was present, but after its conversion to cropland it increased significantly.
H11F-0837
Understanding Pathways of Water-Resource Development: An End-Member, Water- Balance Approach
Concern about the sustainability of human water-use practices is spreading rapidly throughout the world. Regional-scale depletion of aquifers and river systems, dessication of large lakes, and associated degradation of soil, water, and ecosystem quality are typical consequences of contemporary water-use patterns. To facilitate understanding of these patterns and their historical development, it is useful to apply a comprehensive approach to the terrestrial water balance that quantifies the magnitude of human components of the water balance (withdrawals, return flows, transfers) as well as natural components (precipitation, evapotranspiration, ground-water, and surface-water flows). We present such an approach and use it to define four end-member states, or water-use regimes, applicable to any bounded hydrologic system: (1) undeveloped; (2) depleted (withdrawal-dominated); (3) surcharged (return flow and import- dominated); and (4) churned (human-flow-dominated). The pathway by which a system evolves from an undeveloped state toward one or more of the developed end-members constitutes the hydrologic history of a system during its period of human influence. Graphical techniques are introduced to illustrate several hypothetical and real development pathways. The resulting plots help to shed light on the diverse—and in many cases unsustainable—ways in which humans interact with hydrologic systems.
H11F-0838
Assessing the Stability of Hydrologic and Associated Biogeochemical and Geomorphic Regimes Using Historical Reconstructions
This presentation develops a foundation for future research into analyzing the stability of water quality and sediment dynamics by synthesizing existing studies and utilizing knowledge gleaned from contemporary long- term and experimental research sites. We synthesize existing historical biogeochemical and geomorphological studies for the Eastern US and present a possible path toward estimating these system stabilities through time. We hypothesize that understanding how trends in water quality and quantity change over multiple centuries will lead to improved environmental management and planning strategies. A suite of methods (sediment cores and pollen counts, tree rings, and social, historical data) were used to reconstruct historical hydrologic regimes. With this information we then utilize existing studies and contemporary scientific findings to infer biogeochemical and sediment regimes at a regional scale. This methodology explicitly accounts for human actions and highlights fundamental research needs. While uncertainty in reconstructing hydrologic data compounds when analyzing biogeochemistry and fluvial geomorphology, we argue that the trends and trajectories evident from this type of approach yield important insights into human-environment interactions, inform current management/restoration efforts and improve future predictions. One early finding suggests that nutrient management at a river basin scale could be conducted differently throughout the basin depending on current uses, legacy effects, and hydrologic connectivity.
H11F-0839
Humans in Biogeophysical Models: Colonial Period Human-Environment Interactions in the Northeastern United States
Earth system models increasingly require representation of human activities and the important role they play
in the environment. At the most fundamental level, human decisions are driven by the need to acquire basic
resources – nutrients, energy, water, and space – each derived from the biogeophysical setting. Modern
theories in Ecological Economics place these basic resources at the base of a consumption hierarchy (from
subsistence to luxury resources) on which societies and economies are built. Human decisions at all levels of
this hierarchy are driven by dynamic environmental, social, and economic factors. Therefore, models merging
socio-economic and biogeophysical dynamics are required to predict the evolving relationship between
humans and the hydrologic cycle.
To provide an example, our study focuses on changes to the
hydrologic cycle during the United States colonial period (1600 to 1800). Both direct, intentional, human
water use (e.g. water supply, irrigation, or hydropower) and indirect, unintentional effects resulting from the
use of other resources (e.g. deforestation or beaver trapping) are considered. We argue that water was not
the limiting resource to either the Native or Colonist population growth. However, food and tobacco
production and harvesting of beaver pelts led to indirect interventions and consequent changes in the
hydrologic cycle. The analysis presented here suggests the importance of incorporating human decision-
making dynamics with existing geophysical models to fully understand trajectories of human-environment
interactions. Predictive tools of this type are critical to characterizing the long-term signature of humans on
the landscape and hydrologic cycle.
H11F-0840 INVITED
Uncertainty in future water supplies from forests: hydrologic effects of a changing forest landscape
Forests account for 33 percent of the U.S. land area, process nearly two-thirds of the fresh water supply, and
provide water to 40 percent of all municipalities or about 180 million people. Water supply management is
becoming more difficult given the increasing demand for water, climate change, increasing development,
changing forest ownership, and increasingly fragmented laws governing forest and watershed management.
In 2006, the US National Research Council convened a study on the present understanding of forest
hydrology, the hydrologic effects of a changing forest landscape, and research and management needs for
sustaining water resources from forested landscapes.
The committee concluded that while it is possible to generate short-term water yield increases by timber
harvesting, there are a variety of reasons why active forest management has only limited potential to
sustainably increase water supplies. These include the short-term nature of the increases in most
environments, the timing of the increases, the need for downstream storage, and that continuing ground-
based timber harvest can reduce water quality.
At the same time, past and continuing changes in forest structure and management may be altering water
supplies at the larger time and space scales that are of most interest to forest and water managers. These
changes include the legacy of past forest management practices, particularly fire suppression and
clearcutting; exurban sprawl, which permanently converts forest land to nonforest uses; effects of climate
change on wildfires, insect outbreaks, forest structure, forest species composition, snowpack depth and
snowmelt; road networks; and changes in forest land ownership. All of these changes have the potential to
alter water quantity and quality from forests. Hence, the baseline conditions that have been used to estimate
sustained water yields from forested watersheds may no longer be applicable. Stationarity also can no
longer be assumed for the long-term control watersheds that have served as the cornerstone for most
watershed-scale forest hydrology studies. The net result is that forest and water managers are facing
greater uncertainty about future water supplies, water quality, and aquatic ecosystems, and their planning
must consider a broader range of future scenarios than in the past.
In this presentation, we outline a way forward for the research community to address the challenging
questions of the future related to forests and water, and we chart a path for the involvement of various
stakeholder groups to engage in water resources research, monitoring and policy formation.
http://books.nap.edu/catalog.php?record_id=12223#toc
H11F-0841
History of Virtual Water , International Trade and Economic Metabolism at the Time Colonialism and a First Attempt to Assess Their Impact on Hydrologic Changes
This research considers the historical impact of virtual water into the geophysical arena by considering it as
a human-led phenomenon that impacts the hydrologic system and, consequently, the environment as a
whole.
This paper is in line with the idea of including the humans into the water-balance model, and it is deepening
the idea that this has to be done not only at the light of each watershed, but globally, looking at the role of
water-trade embedded in food and tradable goods.
Starting from a definition of what virtual water is, this research explores the role of crops export in the early
U.S. Colonial time. As early as 1630 a huge biomass from here was already exported to the UK (the fur
trade). In 1700 the tobacco export started, along with cereals exports and timber. An entire ecosystem has
been "exported" in terms of water-embedded-in-goods. This was the beginning of a massive depletion of
bio-mass stocks and flows, a raise in nitrogen discharge into the environment and its impact on the
hydrological systems ( CUAHSI Summer Institute findings).
Immigration and its effects on the water balance is also considered in this work.
The experiment of interdisciplinary work of CUAHSI Summer Institute 2008 has proven that there is space for
a historical reconstruction of evidence of human-led changes to the hydrological systems. This has been
possible through the analysis of material stocks and flows, water-balance analysis of these stocks and flows,
including human-led changes like international trade and population growth.
This proposal will argue that these changes can also be identified by the term of
'socio-
economic
metabolism', in which societies are trading their goods internationally but taking the primary resources, including water,
locally.
This work will put the basis for the history of virtual water and its implications on both socio-economic
metabolism and local geophysical changes.
http://www.lse.ac.uk/collections/geographyAndEnvironment/CEPG/LWRG/Default.htm
H11F-0842
Tapping Environmental History to Recreate America's Colonial Hydrology
Throughout American history water has played a central role in biological and economic exchange. Water and the energy derived from it have largely determined patterns of human settlement. Humans, likewise, altered local and regional hydrosystems to meet their needs. Drawing from work generated at the Hydrologic Synthesis Institute held at the Massachusetts Institute of Technology during summer 2008, this study demonstrates that environmental history can generate new and important questions for hydrologists and that the science of hydrology can shed new light on early American history. The summer synthesis institute charted regional hydrologic change from Chesapeake Bay to the St. John River, between 1600 and 1800. Historical analyses that examine the period of first European settlement provide hydrologists with a more accurate understanding of baseline environments and how they responded to the principal drivers of hydrologic change, including human governance, water-engineering, land-cover modification, and climate change. Proxy data, such as colonial census records, import/export statistics, tax information, and weather observations, among others, can produce quantifiable assessments of hydrologic change in the distant past. Examining how regional hydrosystems functioned in the past and how humans changed them over time promises to shed new light on how present and future hydrosystems will respond to human-induced environmental change. The human-water linkage also has profound implications for history. Hydrologic modeling shows promise as a new form of historical evidence. Quantitative analyses of hydrosystems can take historical analyses beyond scattered 'perceptions' conveyed through more traditional anecdotal sources. Hydrologic evidence could provide new insights into patterns of population distribution and land management. Charting the metrics of hydrologic change, such as water availability, residency time, or the timing of peak and low flows, may shed new light on local-scale human social dynamics or even regional-scale political developments of both indigenous and settler societies. Ultimately, our study contends that historical analysis will deliver a new set of questions to the field of hydrology, which will broaden and enrich it. Environmental history, likewise, stands to gain a new empirical lens through which it can view the past, which will shed new light on the development of early American society.
H11F-0843
Preliminary Results from Hydrologic Monitoring of Mill and Farm Ponds in Burgundy, France
This paper presents the preliminary results from a year-long intensive hydrologic monitoring study completed in three small freshwater reservoirs (mill and farm ponds) within the Arroux River Valley, Burgundy, France. The study includes assessment of the seasonal variability of reservoir water levels and chemistry and hydrologic modeling of the watersheds. Several shallow monitoring wells were installed around each reservoir, and groundwater and surface water inflows and outflows were sampled monthly. All water samples were analyzed for major cations (Na, Mg, K, Ca) and anions (F, Cl, SO4, NO2, NO3) as well as stable isotopic composition. Monthly well and continuous reservoir water levels were also recorded. The water monitoring data was combined with nearby weather station data (available from 1955 to present) to model the hydroclimatology and hydrogeochemistry of the reservoirs. This modern data will be used to interpret (i.e., calibrate and validate) geochemical records from sediment cores collected from the reservoirs, which date to at least 1200 A.D. Modern watershed and sediment core data will also be compared with known local land use histories to examine the relative influence of climate and human activity on watershed dynamics. This work thus has broad implications for many watershed studies where historical records of land use and climate change are not available but instead are inferred from geological or ecological evidence.
H11F-0844
Rates and patterns of sediment deposition in the Salinas River basin, Central California
Erosion rates in mountainous watersheds have increased during historic times due to land use changes such as logging, mining, road construction, agriculture, and urban/suburban development. This increase in erosion rates has resulted in (1) increased sediment accumulation in small and/or closed catchments, (2) rapid sediment infilling in reservoirs, and (3) shoreline progradation in large embayments such as Chesapeake Bay and San Francisco Bay. Conversely, land use changes and hydrological modifications in valleys and deltas, such as straightening and levee construction along river channels, favor sediment by- pass. The goal of the research described here is to better understand the composition and fate of sediment eroded from mountainous coastal watersheds, and to specifically put current and recent rates of sediment deposition into a longer-term context. Sediment cores collected from wetlands along the Salinas River, a mid-sized mountainous coastal watershed located in central California, have been analyzed for sediment composition, pollen, and rates of accumulation using radiocarbon, Cs-137, Pb-210, and pollen dating methods. The results of this study show current high rates of sediment accumulation in a high relief portion of the watershed, and lower than background rates of sediment accumulation in the deltaic portion of the watershed.
H11F-0845
Buried Wetlands: The Origin and Evolution of Pre-Settlement Piedmont Valley Bottoms in Pennsylvania and Maryland
In Walter and Merritts (2008) we describe the stratigraphy of Mid-Atlantic Piedmont stream banks to consist of 1-5 m stacks of post-settlement fine-grained sediments overlying a thin organic-rich horizon, which in turn overlies a veneer of gravels on bedrock. We attribute the widespread deposition of the fine-grained sediments to an increase in base level caused by the construction of Early American milldams that lined valley bottoms by the mid 19th Century, and to the filling of extensive millponds with eroded upland soil. Several earlier researchers noted the existence of a dark organic-rich horizon near the base of stream banks in this region, but little attention was paid to their nature or origin. Our studies show that this dark layer formed during the Holocene, and was hydro-climatically stable for at least the last 5,000 yrs. Analyses of extracted seeds reveal obligate and facultative wetland plants, indicating that this horizon should be classified as a hydric (wetland) soil. Trenches and bank exposures show that this wetland soil can be traced across valley bottoms where it overlies coarse, generally quartz-rich gravels that are angular to subangular except where underlain by bedrock composed of rounded gravels. We interpret these basal gravels to be a concentrated lag from denudation of adjacent hillslopes over millions of years, and in places this lag was reworked by periglacial processes. The angularity of the clasts and the lack of fluvial depositional structures indicate that the basal gravels were not transported or deposited by river action. We have found no evidence of a pre-settlement stream channel form in the 1st to 3rd order streams of the 20+ watersheds we have studied to date. The widespread occurrence of hydric soils and the lack of discernable pre-settlement stream channels indicate that valley bottoms were dominated by broad wetland ecosystems. Given that state and federal agencies are spending millions of dollars to create new wetlands, the recognition of buried pre- settlement wetlands presents new opportunities, and a testable model, to guide future stream restoration practices in the region.