Mackinac Falls
Encyclopedia
Mackinac Falls is a drowned 100-foot (30 m)-high waterfall
formation under the waters of Lake Huron
. The formation, which lies approximately 1 mile (1.5 km) east of Arch Rock
on Mackinac Island
, was the former outflow point for water flowing eastward from postglacial Lake Michigan
. The formation was discovered on August 16, 2007.
, the geographic features that would become North America's Great Lakes
significantly changed in shape and size. Glacial melt, catastrophic erosion
events as dammed-up waters found new outlets, and the post-glacial geomorphic rebound of this section of the Earth's crust, caused various freshwater lakes in this area to form, drain away, and re-form.
During one of these periods, dated 10,000 years before the present, what is now the upper Great Lakes drained towards the Atlantic Ocean through a deep channel that passed eastward through Georgian Bay
and what is now the small city of North Bay, Ontario
. This channel was very efficient at draining water; the Great Lakes drainage basin was as big then as it is now, and collected a considerable amount of rainfall, but the upper Great Lakes were physically smaller. In particular, the overall level of Lake Michigan was much lower than its current level of 581 feet (177 m) above sea level. A shrunken Lake Michigan collected water from many now-drowned rivers throughout its bed, and the water drained eastward through a gorge, the now drowned Mackinac Channel, towards a similarly shrunken Lake Huron.
The Mackinac Channel generally followed the pathway of the current Straits of Mackinac
. When the flowing water reached Mackinac Island, it found an impasse; the limestone breccia
of the current island partially dammed the gorge, which formed a horseshoe curve north around the island.
Just east of what is now Mackinac Island
stood the shores of postglacial Lake Huron. Lake Huron's level was approximately 100 feet (30.5 m) lower than Lake Michigan, and it too was shrunken. The Mackinac Channel gorge discharged its water into postglacial Lake Huron through Mackinac Falls.
Later, the North Bay channel was blocked by further postglacial geological changes, and both Lake Huron and Lake Michigan (through Lake Huron) were forced to drain southward into what is now Lake Erie
. The levels of both Lake Huron and Lake Michigan rose towards their current 581 feet (177 m) level, and the two lakes merged hydrologically with each other. Mackinac Falls was completely submerged.
The lip of what was once Mackinac Falls today lies under 110 feet (33 m) of water. The base of the waterfall formation lies approximately 210 feet (63 m) down. The waterfall was discovered on August 16, 2007 by the Great Lakes research vessel Pride of Michigan as it took careful soundings of the lakebed east of Mackinac Island.
Under current geological conditions, the waters of four North American Great Lakes drain through Niagara Falls
, which is 167 feet (51 m) tall. By contrast, Mackinac Falls drained one Great Lake and was 100 feet (30 m) tall.
. It should be possible to use computer-generated imagery
(CGI) to develop an illustration of what Mackinac Falls looked like when it was in operation.
Waterfall
A waterfall is a place where flowing water rapidly drops in elevation as it flows over a steep region or a cliff.-Formation:Waterfalls are commonly formed when a river is young. At these times the channel is often narrow and deep. When the river courses over resistant bedrock, erosion happens...
formation under the waters of Lake Huron
Lake Huron
Lake Huron is one of the five Great Lakes of North America. Hydrologically, it comprises the larger portion of Lake Michigan-Huron. It is bounded on the east by the Canadian province of Ontario and on the west by the state of Michigan in the United States...
. The formation, which lies approximately 1 mile (1.5 km) east of Arch Rock
Arch Rock (Mackinac Island)
Arch Rock is a geologic formation on Mackinac Island in Michigan. It is a natural limestone arch formed during the Nipissing post-glacial period, a period of high Lake Huron levels following the end of the Wisconsin glaciation...
on Mackinac Island
Mackinac Island
Mackinac Island is an island and resort area covering in land area, part of the U.S. state of Michigan. It is located in Lake Huron, at the eastern end of the Straits of Mackinac, between the state's Upper and Lower Peninsulas. The island was home to a Native American settlement before European...
, was the former outflow point for water flowing eastward from postglacial Lake Michigan
Lake Michigan
Lake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron...
. The formation was discovered on August 16, 2007.
Postglacial Straits of Mackinac
During the period that immediately followed the end of the Wisconsin glaciationWisconsin glaciation
The last glacial period was the most recent glacial period within the current ice age occurring during the last years of the Pleistocene, from approximately 110,000 to 10,000 years ago....
, the geographic features that would become North America's Great Lakes
Great Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...
significantly changed in shape and size. Glacial melt, catastrophic erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
events as dammed-up waters found new outlets, and the post-glacial geomorphic rebound of this section of the Earth's crust, caused various freshwater lakes in this area to form, drain away, and re-form.
During one of these periods, dated 10,000 years before the present, what is now the upper Great Lakes drained towards the Atlantic Ocean through a deep channel that passed eastward through Georgian Bay
Georgian Bay
Georgian Bay is a large bay of Lake Huron, located entirely within Ontario, Canada...
and what is now the small city of North Bay, Ontario
North Bay, Ontario
North Bay is a city in Northeastern Ontario, Canada. It is the seat of Nipissing District, and takes its name from its position on the shore of Lake Nipissing.-History:...
. This channel was very efficient at draining water; the Great Lakes drainage basin was as big then as it is now, and collected a considerable amount of rainfall, but the upper Great Lakes were physically smaller. In particular, the overall level of Lake Michigan was much lower than its current level of 581 feet (177 m) above sea level. A shrunken Lake Michigan collected water from many now-drowned rivers throughout its bed, and the water drained eastward through a gorge, the now drowned Mackinac Channel, towards a similarly shrunken Lake Huron.
The Mackinac Channel generally followed the pathway of the current Straits of Mackinac
Straits of Mackinac
The Straits of Mackinac is the strip of water that connects two of the Great Lakes, Lake Michigan and Lake Huron, and separates the Lower Peninsula of Michigan from the Upper Peninsula of Michigan. It is a shipping lane providing passage for raw materials and finished goods, connecting, for...
. When the flowing water reached Mackinac Island, it found an impasse; the limestone breccia
Breccia
Breccia is a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix, that can be either similar to or different from the composition of the fragments....
of the current island partially dammed the gorge, which formed a horseshoe curve north around the island.
Just east of what is now Mackinac Island
Mackinac Island
Mackinac Island is an island and resort area covering in land area, part of the U.S. state of Michigan. It is located in Lake Huron, at the eastern end of the Straits of Mackinac, between the state's Upper and Lower Peninsulas. The island was home to a Native American settlement before European...
stood the shores of postglacial Lake Huron. Lake Huron's level was approximately 100 feet (30.5 m) lower than Lake Michigan, and it too was shrunken. The Mackinac Channel gorge discharged its water into postglacial Lake Huron through Mackinac Falls.
Later, the North Bay channel was blocked by further postglacial geological changes, and both Lake Huron and Lake Michigan (through Lake Huron) were forced to drain southward into what is now Lake Erie
Lake Erie
Lake Erie is the fourth largest lake of the five Great Lakes in North America, and the tenth largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. It is bounded on the north by the...
. The levels of both Lake Huron and Lake Michigan rose towards their current 581 feet (177 m) level, and the two lakes merged hydrologically with each other. Mackinac Falls was completely submerged.
The formation today
Waterfalls are short-lived geological formations. Their successful operation causes them to erode themselves out of existence, and they degenerate into rapids. When Mackinac Falls was submerged, however, it ceased to erode. The formation "froze" underwater in the form that it had been when it disappeared under the water of Lake Huron.The lip of what was once Mackinac Falls today lies under 110 feet (33 m) of water. The base of the waterfall formation lies approximately 210 feet (63 m) down. The waterfall was discovered on August 16, 2007 by the Great Lakes research vessel Pride of Michigan as it took careful soundings of the lakebed east of Mackinac Island.
Under current geological conditions, the waters of four North American Great Lakes drain through Niagara Falls
Niagara Falls
The Niagara Falls, located on the Niagara River draining Lake Erie into Lake Ontario, is the collective name for the Horseshoe Falls and the adjacent American Falls along with the comparatively small Bridal Veil Falls, which combined form the highest flow rate of any waterfalls in the world and has...
, which is 167 feet (51 m) tall. By contrast, Mackinac Falls drained one Great Lake and was 100 feet (30 m) tall.
The formation tomorrow
Further research should develop a precise outline of the formation's geomorphologyGeomorphology
Geomorphology is the scientific study of landforms and the processes that shape them...
. It should be possible to use computer-generated imagery
Computer-generated imagery
Computer-generated imagery is the application of the field of computer graphics or, more specifically, 3D computer graphics to special effects in art, video games, films, television programs, commercials, simulators and simulation generally, and printed media...
(CGI) to develop an illustration of what Mackinac Falls looked like when it was in operation.