Pictured Rocks National Lakeshore National Park Service Grand Sable Dunes U.S. Department of the Interior

Research Natural Area “Wild Beauty on the Lake Superior Shore”

Where Can I See the Dunes? The best place to view the Grand Sable Dunes is from the trail that begins at the west end of the Sable Falls parking area. This trail leads through an old field, then crosses a bridge over Sable Creek. It then ventures into the forest and dunes transition area for approximately 1/4 mile. Wayside exhibits are located along the trail. Another access point for the dunes is from the North Country Trail 1/4 mile east of the Log Slide. Please stay on the trail in both of these areas as the dunes vegeta- tion is fragile.

Dunes Preserved as Research Area The Grand Sable Dunes are among the best examples of perched dune systems in the world. A large portion of Ojibwa life. Early accounts of “les tons of pulverized rock rubble in the dunes is preserved in the Grand Sable Grandes Sables” by lake travellers, various configurations to the south Dunes Research Natural Area (RNA). The beginning with Radisson and Gro- of the Superior basin. The Grand RNA was designated by the Lakeshore seillers in 1658, are well known. No Sable Banks may have originated as in 1994. Research Natural Areas are part known historic sites, per se, are pres- a glaciofluvial kame terrace along a of a national network of field ecological ent in the RNA. glacial rivers during deglaciation. areas designated for research and educa- As ice retreated completely from the tion and to maintain biological diversity. Climate Superior Basin, water levels in the basin They are set aside to provide scientists The Grand Sable Dunes have a receded rapidly northward leaving the with a permanent tract on which there humid continental climate. Winters Pictured Rocks area “high and dry” will be minimal interference in the are long and cold, and summers are about 9500 year ago. This occurred conduct of needed research, inter- short and cool; the growing season as outlet channels to the east re- pretation will be provided primarily averages 107 days annually. The mained at low levels due to the off-site. dunes are in the second most cloudy recent loading of glacial ice. Near The Grand Sable Dunes Research region of the United States, with an the present site of Grand Marais, a Natural Area is located 3.5 miles annual mean cloud cover of 70%. north facing ice contact bluff and west of Grand Marais, Mich., adja- The average annual temperature platform south of it became forested cent to and north of Alger County for Grand Marais is 40.8 degrees F. and remained stable for 4500 years Road H-58. The research area com- Precipitation totals about 31 inches after deglaciation. prises 2.8 square miles, the major per year with maximum amounts Between 6,000 and 4,000 years portion of an active perched dune occurring during the summer. About before present, rebound of the field along Lake Superior within the 32% of the area’s precipitation falls earth’s crust from its “depressed” extreme eastern portion of Pictured as snow; total accumulation of snow state began to accelerate as land Rocks National Lakeshore. The RNA ranges from 130 to 200+ inches. The was relieved of the huge weight of consists of two units; the western unit is proximity of Lake Superior prevents the ice sheets. The rise of the outlet approximately 1630 acres, while the extreme low temperatures in winter of ancestral Lake Superior at North eastern unit is approximately 200 acres. and extreme warm temperatures in The perched dune field of the summer. RNA includes areas of active sand deposition/deflation and interdunal Glacial History areas in various stages of stabiliza- During the Pleisto- tion. The dunes support open, sparse cene epoch, ice sheets plant communities as well as patches of several North Ameri- of jack pine forest. Plant succession can glacial stages ad- has been periodically interrupted by vanced and retreated sand deposition/deflation. Border- through the area. The ing the dunes to the south, east, final major stage of the and west is second growth northern Great Lakean glaciation hardwood forest. completed its advance just southeast of the Green Bay, Wisc., Bay, Ontario, caused lake level to rise Native Americans about 11,500 years ago. A brief re- relatively quickly to a level about 40 The “Gitchee Nagow” (Great advance, the Marquette substage, feet higher than present Lake Supe- Sands) figured prominently in Ojib- occurred about 10,000 years ago in rior, forming glacial Lake Nipissing. wa legend and were reportedly a northern Upper Michigan. As levels of Lake Nipissing rose, traditional site of fasting stations Melting of glacial ice within the the Grand Sable Banks were destabi- which played a key role in religious Superior Basin produced huge lized and formed a north facing ac- ceremonies at important points in rivers that deposited millions of tive colluvial slope. Unconsolidated sand on this slope was entrained by dunes it has been suggested that A basic illustration of this process: predominant northwesterly winds the fates of several rare species are and deposited on the plateau top to tied to specific disturbance regimes form the Grand Sable Dunes. within a shifting habitat mosaic. No permanent lakes or streams These demographic characteristics of occur within the RNA. Several seeps small, isolated populations in highly and springs issue from the base dynamic landscape patches are keys of the Grand Sable Banks where to species persistence over time. ground water is concentrated by an Some paleoecological work has Lake Superior levels high - the base of the impervious sedimentary layer. suggested that landscape distur- banks are de-stablized by lake erosion. No soil profile development can be bance regime is altered by climatic Plants and soils are buried by sand that shifts and species composition in a blows to top of dunes. complex way. Disturbance regimes may undergo step-like shifts that cause rapid change in vegetation as climate varies gradually over time. This suggestion is central to ques- tions about linkage of vegetation patterns and climate. Lake Superior levels low with little basal That habitats and disturbance erosion - dunes are stablized by vegetation regimes on the Grand Sable Dunes as little new sand is blown on top. plateau have changed drastically in the past is witnessed by the presence of “ghost forests” of apparent vari- ous age within the dune field and charcoal fragments associated with several ancient soils. Studies of fire history, rare plant distribution, soils, forest ecology and geomorphology of the dune field Lake Superior levels high - base of and northern hardwood and conifer banks are de-stablized by lake erosion. forests surrounding it suggest that Plants and soils are again buried by many drivers of landscape dynamism wind-driven sand. interact in the dunes. This complex observed in modern surface deposits. interaction produces distinctive pat- For additional information, visit : Several paleosols buried at different terns of community types, species www2.nature.nps.gov/geology/ times over the past 5,000 years are pres- richness, and patch turnover within a tour ent and reflect paleoecological condi- relatively small area. Pictured Rocks National Lakeshore tions over that time period. Most are not P.O. Box 40 readily seen by the casual observer. Climate and Lake Level Changes Munising, MI 49862 The most abundant large mam- History and mechanisms of 906 387 2607 mals in the vicinity of the RNA are change in levels of the Great Lakes www.nps.gov/piro 03/2007 the white-tailed deer and black bear. have been investigated on several A deer yard is located northeast of scales. Major episodes of high and Grand Sable Lake and a few deer low water have been identified usually winter in jack pine patches through beach ridge studies. Finer in the eastern portion of the dunes. scale late Holocene changes are not Bald eagle soar in the area and com- well understood, particularly on Lake mon harriers drift over the open Superior. stretches. It has been hypothesized that Dune grass, Lake Huron tansy, sand supply to the Grand Sable jack pine, and balsam poplar are Dunes decreases during periods of common in the dunes. More uncom- stable or lowering lake levels be- mon residents (and protected by cause of diminished basal sapping law) include Pitcher’s Thistle, grape and armoring of the upper slope ferns, and orchids are found here through exposure of coarse frag- also. ments; dune building episodes are the result of rising lake level. More Geomorphic Dynamism recent soil stratigraphy work sup- Research has shown that lake ports this hypothesis. One wide- level changes, wind and wave re- spread and well developed paleosol gimes are drivers of geomorphic and several other buried soils of change and that this change has local extent are present in the dunes. influence on coastal vegetation The Grand Sable system represents patterns. Many rare or relict plant one of the few areas in the northern communities and species occur in Great Lakes where buried soils are unusual habitats within the coastal preserved and material is available zone. Fluctuating lake levels have for radiocarbon dating. It appears built and destroyed time synchro- that evidence of fine scale changes nized sites some of which have been in the levels of Lake Superior are utilized in studies of plant succession present in the dunes. and rates of soil formation. From studies of plant assemblages on the

“There are certain restrictions on the use of RNA’s - please contact a park visitor center or headquarters office before entering.”