Интерстейт-Парк: Геология и Природное Наследие Миннесоты и Висконсина

Interstate Park comprises two adjacent state parks on the Minnesota–Wisconsin border, both named Interstate State Park. They straddle the Dalles of the St. Croix River, a deep basalt gorge with glacial potholes and other rock formations. The Wisconsin park is and the Minnesota park is The towns of Taylors Falls, Minnesota and St. Croix Falls, Wisconsin are adjacent to the park. Interstate Park is within the Saint Croix National Scenic Riverway and the Ice Age National Scientific Reserve. The western terminus of the Ice Age National Scenic Trail is on the Wisconsin side. On the Minnesota side, two areas contain National Park Service rustic style buildings and structures that are listed on the National Register of Historic Places.

Rocks or sediment from three short intervals of geologic time, each from three different geological eras, Precambrian, Paleozoic, and Cenozoic, are exposed at the surface within Interstate Park. The oldest strata are of the Keweenawan Supergroup, which is a 2.5 mile (4 km) thick sequence of volcanic and sedimentary strata that fill a segment of the Midcontinent Rift System. During the formation of the Midcontinent Rift System, these strata accumulated about 1.1 billion years ago as a series of basaltic lava flows and alluvial fans filled an ancient rift valley to depth of over 2.5 mile (4 km). At least ten separate lava flows are exposed within the region of Interstate Park. Since their accumulation, these strata within Interstate Park area have undergone very low to low grade metamorphism.

In the Cambrian period of the Paleozoic Era, between 530 and 470 million years ago, the region was covered by a shallow sea which deposited sandstone and siltstone atop the basalt. This epoch of the Cambrian, the Furongian, was originally called the Croixian in North America because the layers exposed in this area were its type locality.

The presence of older glacial deposits south of the Interstate Park demonstrates that the Laurentide Ice Sheet repeated glaciated it and surrounding areas over the Pleistocene Epoch. Within Wisconsin, these older glacial deposits consist of remnants of, highly weathered dark gray loam till and lake sediment with reversed magnetic polarity and a deeply weathered, pre Sangamonian Stage, reddish brown, sandy loam till with normal magnetic polarity. Both the landforms and deposits related to these earlier glaciations have been either eroded or buried by the latest advance of the Laurentide Ice Sheet over this area of the Last Glacial Maximum. The region of Interstate Park was deglaciated sometime between about 19,000 and 14,000 BP calibrated (16,000 and 12,000 14C uncalibrated). During this time, the Superior Lobe had retreated from the St. Croix Moraine northeastward to the Thompson Moraine. Between 14,000 and 11,500 BP calibrated (12,000 and 10,000 14C uncalibrated), an extensive set of ice marginal channels drained meltwater from the Thompson Moraine by way of the Brule channel into the newly formed St. Croix River. The glacial landforms and sediments of Interstate Park were largely created during the retreat of the Superior Lobe from this region and periodic outburst flood events from proglacial lakes, e. g. Lake Duluth, since the Last Glacial Maximum. First, the retreat of the Superior lobe into the Lake Superior basin created proglacial lakes. Initially, these lakes consisted of small, proglacial lakes. Later, these lakes coalesced to form a large proglacial lake called glacial Lake Duluth, which was confined to the western Superior basin. The most prominent of multiple lake levels of glacial Lake Duluth is known as the Duluth level. There also was an older epi Duluth level that lay above the Duluth level. The epi Duluth level and a smaller precursor proglacial lake, named Lake Nemadji, drained through the higher Moose Lake (Portage) outlet into the Kettle River and into the St. Croix River. As the Lake Superior Lobe retreated, the Brule outlet opened and the higher Moose Lake was abandoned as a lower Duluth level was quickly established by massive and sudden outflow through the lower Brule outlet and down St. Croix River. The Brule outlet was abandoned when Lake Superior Lobe retreated from the Keweenaw Peninsula and opened lower eastward draining outlets. This caused the Duluth level to drop abruptly to post Duluth levels and water to cease flowing into lower Brule outlet and down the St. Croix River. The deep inner channel, which includes the Dalles, that forms the modern St. Croix River valley was excavated by a second drainage event. This inner channel is incised as a narrower valley cut into, and hence younger than, the Chengwatana surface. This demonstrates that the St. Croix valley is slightly younger than the Kettle River valley and Moose Lake outlet and was cut by water flowing out of the lower and younger Brule outlet of the Duluth level of glacial Lake Duluth. Because the trace of the Chengwatana surface grades to a terrace level higher than the potholes in International State Park, they were eroded by spillway water from Duluth level of glacial Lake Duluth. When the massive flow of water through the Brule outlet and down the St. Croix River ceased, the potholes became exposed to the air. Dirt, vegetation, and rainwater have collected in them, disguising their true depths. Some have been excavated; one, the Bottomless Pit, is 10 feet (3 m) wide and 60 feet (18 m) deep, the deepest explored pothole in the world. A former formation on the Minnesota side called the Devil's Chair looked like a high backed throne.

Several habitats are found within the parks. Originally most of the land was forested with large eastern white pines, but was denuded by loggers. Mammals found in the parks include white tailed deer, foxes, raccoons, gray squirrels, river otters, minks, skunks, muskrats, and beavers, and 150 species of birds have been identified in the park, The first Europeans to pass through the Dalles were Daniel Greysolon, Sieur du Lhut, and his 1680 expedition, though he made no particular mention of the site Fur traders used the river extensively, and a French fort was located near the Minnesota campground in the early 18th century. To control the water flow and prevent further catastrophic jams, the Nevers Dam was built upstream in 1890 in what is now Wild River State Park. The walls of the Dalles rise from 50 to 250 feet (76 m) above the river. During this same period, the Dalles of the St. Croix became a popular visitor attraction. Steamboat service to Taylors Falls began in 1838, and a railroad connection was finished in 1880. A travel agent named George Hazzard became the leading advocate for a park, and gained the support of newspapers, several landowners in the area, influential people like W. H. C. Folsom, and ultimately the state senator and representative. These last two introduced a bill to the Minnesota Legislature calling for the creation of the State Park of the Dalles of the St. Croix and urging cooperation with Wisconsin to protect both sides of the Dalles. Hazzard and his allies had a more difficult time lobbying the Wisconsin Legislature, but succeeded in 1900 with the creation of the first state park in Wisconsin,

U. S. Route 8 descends through the Minnesota park in a road cut blasted in 1931. The Minnesota Department of Transportation built stone overlooks and guardrails along the highway in the mid 1930s. Civilian Conservation Corps Company 633 arrived in 1935, building roads, trails, picnic grounds, plumbing, the beach and beach house on Lake O' the Dalles, and retaining walls. They are considered significant as examples of New Deal federal work relief, early state park development, National Park Service rustic design, and—in separating the intensive use of camping and picnicking from the open air museum of the Glacial Gardens—landscape architecture. The Interstate State Park CCC/WPA/Rustic Style Historic District at the northeast end of the Minnesota park contains six contributing properties. These consist of three buildings, two structures, and an object. Noteworthy are the women's rest room (built c. 1920) and men's rest room (built 1928), which predate the federal developments and influenced the WPA's use of rustic style in the park. These two buildings are situated at the north end of the parking lot; the men's rest room is noted for its placement relative to the rock outcroppings and the women's rest room was modified by the WPA in 1941. The third contributing building is the 1939 Refectory, originally a concession building renovated in 1981 with restrooms and office space to become the current visitor center. The two contributing structures are the 1937 stone curb in the parking lot and a 150 feet (46 m) retaining wall built in 1938 at the south end of the Glacial Gardens. The contributing object is a 1938 water fountain at the south end of the parking lot.

In April 2005 a landmark rock formation called the Devil's Chair collapsed. An investigation found that the basalt pinnacle was toppled by vandals using crowbars and possibly a hydraulic spreader. Despite a reward for tips, the culprits have never been identified.

Located an hour's drive from Minneapolis–Saint Paul, Interstate Park has received annual visitation comparable to many U. S. national parks since the 1930s. The Minnesota park has a campground with showers and 37 sites, 22 of which have electrical hookups. A group campsite accommodates up to 100 people. There are 4 mile (6 km) of trail. Certain sensitive areas, as well as all potholes, are off limits to climbing.