Historical Geology: The most recent chapter in the geologic story is that of the modern landscape as it appeared to the first European explorers who arrived in the Little River Valley, and its subsequent modification to make way for agriculture and urban development over the ensuing centuries. Of necessity, this part of the story takes place at the intersection of geology, ecology, and human history. Geology-particularly the hydrological aspect-plays a central role in both the ecology of the Great Marsh, and in the patterns of human settlement and use of the region. The accompanying map of the upper Little River Valley shows some of the key aspects of this relationship, depicting the main geological elements in and around the valley, along with major ecological and historical features through time. The Wabash Valley was a key travel and trade route for both the early explorers and for Native Americans. The ability to navigate the Little River to within striking distance of the St Marys River was crucial to the success of the route, and ultimately led to Fort Wayne becoming established as the ‘Summit City’ along the portage between the two drainages.
Early Hydrologists: When explorers ventured up the Wabash River from western Indiana in the early 1700’s, they encountered a vast marsh that covered virtually the entire floor of the Little River Valley between Huntington and Fort Wayne. The marshy expanse was broken only by a few, small wooded dunes, or islands. In time, this wetland became known as the “Great Marsh,” and while it presented a major impediment to settlement, it also acted as a navigable waterway of great strategic value, not only to the early settlers and traders, but also to the Native Americans of the region. In all but the driest times, it was feasible to canoe up the river from the forks of the Wabash to a position just northwest of Fox Island. From there, the portage followed the slightly drier terrain along the northern edge of the valley to the St. Marys River, crossing the continental divide in the process. Some accounts also describe the ability to canoe all the way to the St. Marys during wet periods that typically occurred between late winter and early summer, whereas other less fortunate travelers sometimes had to portage the entire 24 miles when making the trip during the dry late summer and fall months. These early accounts are the first to suggest the seasonal hydrology of the Great Marsh. The continental divide near the east end of the portage later became the high point along the Wabash & Erie Canal, hence Fort Wayne was dubbed the ‘Summit City’--a somewhat ironic term, since the ‘summit’ it refers to actually is only a few feet above the lowest elevation in the whole regional landscape!
The Little River Valley was widely utilized by the Miami Nation as a source of fish and game, for travel, and for its strategic value.
Two of the more intriguing Native American locales in the Little River watershed are the Cranberry--a complex of bogs and swamps in the uplands along the continental divide near what is now Bass Road and Interstate 69--and the south channel of the valley near what is now Waynedale, which probably served as an ‘alternative’ portage or water route between the St. Marys River and the Little River.
The Miami in the Little River Valley: Native Americans plied the waterways of the Little River Valley long before European settlers arrived, and continued to do so well into the 1800’s. Much has been written about ‘Kekionga’, the Native American village at the Three Rivers confluence that served as a hub of Native American commerce for the same physiographic reasons that the Little Wabash portage became the focal point of competing European interests. Here, we simply point out two lesser-known places along the continental divide whose significance to the Miami stems from their geological underpinnings. The potential use by the Miami of the south channel as an ‘alternative’ portage, or water route, between the St. Marys River and Little River is particularly intriguing, given their choice of location for the Pinšewa (Richardville) House and the fact that the Miami selected the south side of the valley for the majority of the reserves granted by the Treaties of 1818 and 1826. In light of this particular geography, a reasonable person could readily infer that the Miami made regular use of the south channel as a primary travel route, though there is scant documentation to that effect. It is known that Richardville maintained a primitive dam on the small tributary creek leading from behind the Pinšewa House to the St. Marys River, whose purpose seems to have been to back up the water to the continental divide that lay just to the west in the south channel, thereby facilitating a nearly continuous canoe route to the Wabash River system. Only a short portage somewhere in the vicinity of what is now Ardmore Road would have been necessary to reach the Little River, if that. The topography in the bottom of the south channel is extremely subtle, and it isn’t entirely clear where the continental divide originally crossed it. The use of the dam by Richardville suggests that the location wasn’t static, even back then.
Another place that was of special significance to the Miami is known as ‘The Cranberry’. Located in the far northern reaches of the Little River watershed, the Cranberry consists of a complex of wetlands that straddle the continental divide. The Cranberry is situated within a prominent topographic sag that circumscribes an arcuate course between Shoaff Lake and the mouth of Cranberry Creek at Eagle Marsh. The sag appears to mark the ice- marginal drainage in front of a minor Erie Lobe moraine, and the Cranberry lies right at its summit, in the extreme northwestern part of Wayne Township. Chief Lagro requested that one of his reserves adjoin the Cranberry, whose name presumably derives from the highbush cranberry (Viburnum triloba) that populates the shrub swamps there. Much of the Cranberry remained rural through most of the 20th century, due in part to its wetness, and partly because it is geographically isolated by the railroad embankments that run through it. The Cranberry still retains prime examples of the kinds of landscapes (wet woods, shrub fens, marsh) that were once common in the uplands in the Little River watershed, but the remaining pieces of this ecosystem are increasingly being encroached upon by housing additions and industrial development.
Hydrology of the Great Marsh Ecosystem: The map shows the extent of the marsh and the position of the continental divide as they might have looked around the time the first Europeans arrived here. The locations of the actual channel of the Little River through the marsh, and of various small waterways tributary to it, are also depicted. The original configuration of these streams is reconstructed from historical maps and accounts, modern topographic maps, and from patterns visible on aerial photographs, and is somewhat speculative at places due to the large number of meander scrolls and other features that criss-cross the floor of the valley and mark multiple generations of recent stream channels. The gradual migration of these small stream channels across the floor of the valley was one of the key geologic processes that continually shaped the ecosystem. The channels formed narrow ribbons of open or semi-open water amidst a sea of grass. They probably supported large numbers of aquatic plants, mussels, and fishes of various sorts, along with a wide range of shore birds that fed on them. The adjacent areas included true marsh--that is, communities dominated by sedges and marsh grasses that were inundated on a continuous or semi-continuous basis--along with large expanses of wet prairie, which stood slightly higher and were inundated only seasonally. The distributions of these different natural communities were determined by subtle changes in elevation across the exceedingly flat valley floor; a differential of mere inches probably determined whether a particular area was open channel, marsh, or wet prairie. In contrast, the sand dunes were islands that stood well above the prevailing water level of the marsh. They supported a completely different ecosystem-a diverse, mesic hardwood forest composed of enormous sugar maples, beech, tulip tree, oaks, and hickories, with a rich understory of spicebush, pawpaw, ginseng, and large numbers of wildflowers. The water that fed the marsh came from several sources.
Some water came from precipitation that fell directly on the marsh, but an even larger share was derived from several tributaries that drained adjacent uplands. The main stem of the Little River, for example, originated as a series of small upland creeks in northern Wells County, just north of Ossian, and drained a land area of almost 15 square miles. The upland drainage coalesced into a major stream that entered the south channel just below the intersection of Ardmore Road and Lower Huntington Road. The former mouth of the stream is marked by a small but prominent alluvial fan, where sediment carried down from the adjacent upland promptly fell out when the stream encountered the flat bottomland of the south channel. Another sizable tributary was Cranberry Creek, now known by the less poetic name of Graham-McCullough Ditch, which drained an upland area of comparable size on the north side of the valley and debouched into the valley near Eagle Marsh. But by far the most dramatic influxes of surface water came from large floods on the St. Marys River, which periodically overtopped the low divide at the head of the north channel and sent large sheets of water down the Little River Valley. It is impossible to say how frequently this might have occurred in the natural hydrologic regime, because records have not been kept for long enough to reliably estimate the recurrence interval of such extreme floods. The most recent occurrence (and the only well documented one) was the flood of 1913--the largest ever recorded on the St Marys River- -when an estimated 5,000 cubic feet per second (cfs) spilled over the divide, out of a peak flood flow of 24,000 cfs on the river. To put this in perspective, 5,000 cfs is equivalent to 3.25 billion gallons per day, enough to flood Eagle Marsh to a depth of 14 feet! In this way, the Little River essentially acted as a natural safety valve, thereby lowering the peak flood discharges of the St. Marys River, in this instance by more than 20%.
Much of the marsh in the upper valley is inferred to have been fringed by fens, seepage swamps, and other ecosystems supported by the discharge of ground water to the surface. The source of the ground water is sand and/or gravel bodies of various sizes, including the dune fields, the outwash fan at Sand Point, and scattered terraces along the valley walls, all of which act as local aquifers. Precipitation infiltrates the surfaces of these permeable bodies relatively easily, seeps downward to the water table, and then travels laterally to the edge of the valley, where it discharges via springs and seeps. A good example of this process can be seen in Eagle Marsh Woods, where ground-water seepage from the bases of sand dunes is readily visible in most years from late winter to early summer. Additionally, extensive buried sand and gravel aquifers that occur beneath the glacial till and other surficial deposits on nearby uplands are locally truncated along the valley walls or extend out beneath the valley floor. The discharge from these artesian aquifers is potentially substantial and supports at least one fen near Eagle Marsh. In fact, the Little River Valley acts as a regional ground-water discharge area for the entire hydrogeologic system, as there is ample evidence of upwelling ground-water from water-bearing strata at considerable depth below the valley floor, including aquifers in the limestone bedrock.
The Draining of the Great Marsh: By the 1870’s, Fort Wayne had grown from a small outpost to a respectable-sized town. The Little River Valley, which remained largely undeveloped, had come to be known as the ‘Marshy Prairie.’ A variety of parties began pushing for the marsh to be drained, not least among them being local agricultural interests. Legislation to drain the Great Marsh cleared the state legislature and drainage work began in earnest in the late 1870’s.
This drainage work occurred against the backdrop of a major period of drainage projects and agricultural expansion throughout the state (the Grand Kankakee Marsh also was drained during this time), when wetlands generally were not held in high regard by most of the public. This period gave rise to the first drainage laws, which gave unprecedented power to local units of government to take private property and ‘improve’ it by implementing vast drainage projects that forever altered the landscape, all at the property owners’ expense.
After several attempts, by the late 1880’s, the Great Marsh was largely drained. In the portion of the Little River Valley shown on the map, this was achieved by creating three main drainage ditches and many minor ones. One of the first drainage projects, completed by 1880, created Fairfield Ditch, which literally decapitated the Little River by diverting its headwaters out of the watershed and into the St. Marys River across from Foster Park. Imitation is the sincerest form of flattery, so one is led to wonder whether this bit of artificial stream piracy was inspired by recent recognition of the earlier geologic history of the Maumee River. In any case, by removing one of the major sources of upland runoff into the valley, the completion of Fairfield Ditch expedited the completion of drainage projects in the rest of the marsh. A second project which had a similar effect was the building of Graham-McCullough Ditch, which contains Cranberry Creek within a massive earthen levy as it crosses Eagle Marsh. For thousands of years, this waterway had been providing the lion’s share of the water budget to the north side of the marsh in the vicinity of Eagle Marsh. It also delivered a steady supply of sediment to the marsh, which replenished soil and nutrients, and helped maintain the surface of the marsh. A low alluvial fan rings the former mouth of the creek and attests to its former role in that part of the ecosystem. The other major project, and the one that probably had the most profound effect on the overall shape of the watershed, was the establishment of Junk Ditch. Junk Ditch was created by stringing together pieces of existing drainages with newly excavated ditch segments. The lower, more winding portions of Junk Ditch that lie east of the original continental divide follow a natural drainage to the St. Marys River that appears on several historical maps prior to 1880. Some of the upper sections of the ditch utilize former courses of the Little River drainage, while others are simple, straight channels excavated across the former marsh. All told, the advent of Junk Ditch removed several square miles of former marshlands and adjacent uplands from the Little River watershed and shifted the position of the continental divide westward by as much as three miles in some parts of the valley floor.
Agriculture quickly expanded across the fertile soil of the old marsh. The wet, mucky soil supported moisture-loving crops such as onions, lettuce, and celery. In fact, the valley became well known for its celery production around the turn of the century. Persistent wetness posed frequent challenges to cultivation, however, and accounts of draft animals submerged up their bellies in the mucky soil were common. These problems continued after vegetable production was abandoned and the fields were converted into the typical grain crop rotation of corn-soybeans-wheat following World War II. Even extensive systems of closely-spaced drainage tile, ditch laterals, and large pumps running 24 hours a day-a costly undertaking in the contemporary industrial farm economy-were sometimes not enough to keep the water at bay and prevent crops from being lost to inundation.
One of the ironies of modern farming in the Little River Valley is seeing these elaborate measures for draining the soil juxtaposed with large center-pivot irrigation systems that pump millions of gallons of fossil ground water to irrigate the crops. An unforeseen result of draining and cultivating the mucky soils of the Little River Valley is the loss of organic sediment from the land surface: when the soil surface dries out, the organic matter oxidizes and blows away, leading to a long-term reduction in soil fertility and tilth, and a gradual deflation, or lowering, of the land surface.
The ongoing challenges to successfully farming the valley bottom in an age of rock- bottom crop prices, coupled with increased local awareness of the many values of wetlands, form the backdrop for the restoration of portions of the Great Marsh. Both the challenges and the opportunities involved in a large-scale restoration are exemplified at Eagle Marsh, one of the largest contiguous wetland restorations ever undertaken in Indiana. The habitat map shows the layout of natural communities and gives a good sense of how they relate to the current hydrologic regimen.
The restoration is designed to emulate the original bottomland communities of the marsh, while adapting to a condition of relative water scarcity. One of the largest challenges is the lack of a regular source of surface water flowing into the marsh: ditching and channelization of the Little River and Cranberry Creek prevent these streams from interacting hydraulically with the surrounding valley bottom, whereas the various ditches and berms for roadways that cross upstream portions of the valley inhibit the sheet flow of water to downstream portions. As a result, the water budget relies heavily on precipitation falling directly on the marsh, so retaining that water in the marsh is a top priority of the restoration. In addition to decommissioning the extensive drainage infrastructure that existed on the property (e.g., breaking tiles, plugging ditch laterals, removing pumps), earth moving was undertaken to enhance or recreate some of the old meander scrolls. Although these basins are isolated in a hydraulic sense, they help retain water that might otherwise run off; just as importantly, these small areas of open water serve as crucial habitat in the lifecycles of many marsh dwellers ranging from the tiniest insect larva to large shorebirds, and so form a key link in the marsh ecosystem.
Another significant unknown involves uncertainties about the hydroperiod of different portions of the marsh. In simple terms, ‘hydroperiod’ refers to the length of time a particular wetland remains inundated during the course of a typical year: for example, a marsh is typically inundated for all, or almost all, of the year, whereas a wet meadow usually has water standing on the surface for only a portion of the year, while many wet prairies and forested wetlands may be inundated only briefly.
In reality, there is much hydrologic variability both within a particular type of wetland and among different types, and factors such as the depth of water and the time of year inundation occurs (i.e., whether and when during the growing season) have a tremendous influence on the type of natural community found in a given wetland. The lack of detailed historical records documenting this kind of information in the original marsh, coupled with the major hydrologic alterations in the valley, leads to considerable uncertainty and suggests that current hydrological conditions are likely to be quite different, and potentially drier and more variable, than those that existed prior to European settlement. One way this uncertainty is being addressed in the restoration is by incorporating extensive prairie areas in the former marsh landscape, composed of plant species which are well adapted to large seasonal swings in moisture availability. Relative to the original landscape, the restored marsh undoubtedly has a greater proportion of wet prairie than true marsh, out of hydrologic necessity. Another adaptation is the use of a highly diverse mix of plants (see Seeds Planted at Eagle Marsh 2008 and Seeds Planted at Eagle Marsh 2007, which increases the probability of success in a drier or more variable hydrologic system. If some areas turn out to be too dry for certain plants, their place in the ecosystem will be taken by other species better adapted to the prevailing conditions. One of the most interesting aspects of the restoration is seeing how the hydrology of the marsh plays out over the long term, and which species ultimately flourish in which environment--more or less like a grand ecology experiment on a scale never before undertaken.
The material on this webpage was created by geologist Tony Fleming and reviewed by Dr. Jack Sunderman.