Visitors to the park can view the ancient geological history of Minnesota as they walk the path leading from the falls down to the Mississippi River.
 The uppermost layer of soils and gravels of Minnesota were deposited by the most recent Ice Age, about 10,000 years ago.
  Four great ice ages have swept away all traces of the more recent Mesozoic and Cenozoic eras in the Twin Cities area, however standing at the upper falls, one is standing directly on the Platteville Limestone Formation laid down during the Ordovician Period of the Paleozoic Era.
 During the Ordovician Period, about 450 million years ago, the North American continent was situated along the equator and a warm shallow sea covered much of Minnesota.
Sea life was abundant and a large number of marine fossils including corals, bryozoans, brachiopods, clams, snails, cephalopods, and trilobites can be found in the limestone and shale sediments at several areas in the Twin Cities and along the Mississippi River in the park.

Descending to the base of the falls one passes through the layered Platteville Limestone Formation and a thin layer of Glenwood Shale.
 At the base of the falls one enters the level of the Saint Peter Sandstone Formation of pure white quartz sandstone.
 The Minnesota St. Peter Sandstone is "famous the world over as the example of a well-rounded, well-sorted, pure quartz sand.
 It is the Ivory Snow of sediments, because it is close to 99.44% pure".
This sand was first deposited as beach sand, probably eroded from earlier Cambrian sandstones, along the shores of the Ordovician sea.

At places in the park, especially closer to the Mississippi River, one can see the Glenwood Shale Formation.
 This thin layer of grey-green rock was probably deposited in deeper-water offshore from the beaches, and now has been exposed by erosion.
Together, the three formations that are visible as one walks from the falls to the river represent a sequence of sea-level rise which occurred during the Ordovician period.
Visitors to the park can view the ancient geological history of Minnesota as they walk the path leading from the falls down to the Mississippi River.  The uppermost layer of soils and gravels of Minnesota were deposited by the most recent Ice Age, about 10,000 years ago.   Four great ice ages have swept away all traces of the more recent Mesozoic and Cenozoic eras in the Twin Cities area, however standing at the upper falls, one is standing directly on the Platteville Limestone Formation laid down during the Ordovician Period of the Paleozoic Era.  During the Ordovician Period, about 450 million years ago, the North American continent was situated along the equator and a warm shallow sea covered much of Minnesota. Sea life was abundant and a large number of marine fossils including corals, bryozoans, brachiopods, clams, snails, cephalopods, and trilobites can be found in the limestone and shale sediments at several areas in the Twin Cities and along the Mississippi River in the park.
Descending to the base of the falls one passes through the layered Platteville Limestone Formation and a thin layer of Glenwood Shale.  At the base of the falls one enters the level of the Saint Peter Sandstone Formation of pure white quartz sandstone.  The Minnesota St. Peter Sandstone is "famous the world over as the example of a well-rounded, well-sorted, pure quartz sand.  It is the Ivory Snow of sediments, because it is close to 99.44% pure". This sand was first deposited as beach sand, probably eroded from earlier Cambrian sandstones, along the shores of the Ordovician sea.
At places in the park, especially closer to the Mississippi River, one can see the Glenwood Shale Formation.  This thin layer of grey-green rock was probably deposited in deeper-water offshore from the beaches, and now has been exposed by erosion. Together, the three formations that are visible as one walks from the falls to the river represent a sequence of sea-level rise which occurred during the Ordovician period.
Minnehaha Park (Minneapolis)