Huron Creek Falls: Lava and water shaping the land
Cache Summary: There are few natural beautiful places left within city limits across the developed world. Huron Creek falls, behind the Northern Foot Care Center in the far north west of Michigan’s Upper Peninsula, is one of them. It is tucked between residential neighborhoods and the fast developing Houghton, Mi. business district. Upstream and down from this natural fragment, the Huron Creek has been greatly impacted by direct and indirect human interactions. It is also one of the few spots in the watershed where the bedrock peaks out from the Quaternary glacial till that covers much of its area. This peak into the past will give us a look at how water works together with geologic history to shape the features we see in our landscape today.
A picnic spot is to be developed here. It is difficult to get down near the water due to the surrounding steep slopes. There is a nice view from above just next to the foot doctor parking lot.
Figure 1.Huron Creek Falls.photo credit: Jenny Doezema.
Waypoint: 47° 6.966'N 88° 35.214'W when you arrive at your waypoint look down into the ravine at the falls below. Then observe the outcrop around it.
Why did Huron Creek Waterfall form at this location?
Reading the rocks can tell us much about why our landscape is what it is. Huron creek waterfall gives us a glimpse into how the combination of lava and flowing water assist in the formation of some of the exciting destinations in our landscape today.
The falls run over the same rock formation that is responsible for the Keweenaw Peninsula’s famous mining history.
The fall's flow through a bedrock formation called the Portage Lake Volcanic Series. This thick Precambrian aged flood basalt filled an ancient rift valley 1.1 billion years ago. The mid-continent rift formed from a hotspot deep under the crust. This rift spread through North America from East Kansas bending up through Lake Superior. It was slowly filled and depressed by many a massive layer of lava and conglomerate bedrock over 6000 feet thick in some places. This geologic event is responsible for the formation of both the Lake Superior Basin and the Keweenaw. See diagram below.
Figure 2.Cross section of the Lake Superior Basin showing the Portage Lake volcanics and the fault lines. Source: http://en.wikipedia.org/wiki/File:Keweenaw_structure.jpg
The Portage Lake Volcanics are famous for providing the Keweenaw and the world with large amounts of native copper. Native copper is found in amygdaloidal basalts and interbedded layers of conglomerate. The combination of mineral content, unique cooling speed, and temperature stratigraphy made this flow unique in its native copper formation. In fact, it is one of the only places in the world where native copper is formed. Hot water containing dissolved coper and other minerals moved upward from deep within the rift and invaded open spaces in the conglomerate & the spaces provided by the bubbles. The amygdaloidal basalts are the section of the flow where many bubbles are trapped and cool at faster speed than the smooth flow center.
Figure 3 This is an image of the Multiple flood basalt flows of the Columbia River Basalt Group in the Columbia river plateau in the Western U.S.. It is a flood basalt formation. It shows a more dramatic representation of a flood basalt. It’s a good example of the more dense bottom and center of a flow. The eroded crumbly looking section is the flow top. Source: http://simple.wikipedia.org/wiki/Flood_basalt
The center of the lava flow contains few bubbles. The center looks more uniform in color and texture. It’s dense and does not crumble or erode easily. There is a distinct difference in the flow center and the flow top. The bubbly amygdaloidal nature of the flow top makes it break down easier than the center. This distinction allows us to identify the tops of flows, separate one flow from the next, measure thicknesses of a flow, and much more. If you walk the shoreline of the Keweenaw you will see many different flows in sequence. The flow tops are eroding away and the flow center and bottom remain more intact creating dozens of little parallel peninsulas along the shore.
It is this phenomenon that led the waterfall to this place. The consistent battering of powerful Lake Superior waves has weathered away the less resistant lava flow tops. The force of moving water in the Huron Creek behaves like the shoreline waves, carving out a rock valley in a lava flow top as it flows. Just as we people often like to do, water takes the path of least resistance. The creek has found its way through the less resistant flow top of the portage Lake volcanic series. As the water runs through this channel it cuts down into the bedrock. At this location water has found a spot where flow top of an underlying flow has eroded away faster than the bottom of the flow above. This has slowly created a ledge or cliff for the water to tumble down. This is the partnership of water and lava that created this sweet little spot in town.
Logging your visit: Please email me responses to the following questions
Logging question 1: Based on what you have learned about lava anatomy, describe how this spot has been shaped by existing lava and flowing water. Do you see an example of the flow top? Flow center or bottom? Explain where you think these are in reference to the creek and the foot doctor. Explain what helped you identify the two.
Logging question 2: Observer the rock wall across the creek and notice how itchanges in color as you move down towards the water. Please describe this change especially what you see very close to the water at the bottom.
Bonus: Visit two additional waypoints. Downstream the mouth of the creek flows into the Portage lake at (47° 7.254'N 88° 35.147'W ). Upstream the creek flows through an area of broad impact to the watershed at ( 47° 6.440'N 88° 35.183'W ). List the different environmental impacts that may be affecting these other areas.
If you would like to learn more check out the Huron Creek Water Shed Management Plan found at http://www.geo.mtu.edu/~asmayer/HuronCreek/HuronCreek.htm or look at the Mining Gazette article posted in April of 2008: Huron Creek Clean-Up http://www.mininggazette/page/content.detail/id/500164.html
Earth science literacy principle: Big idea 4. Earth is continuously changing
4.3 Earth’s interior is in constant motion through the process of convection, with important consequences for the surface.
4.7 Landscapes result from the dynamic processes that form and uplift new crust and processes that destroy and depress the crust.
4.8 Weathered and unstable rock materials erode from some parts of the Earths surface and are deposited in others.
The hotspot that created the rift, which resulted in the outcrop we see at the Huron Creek Fall’s is an example of Earth’s interior convection. This convection formed hotspot changed the surface of the Earth in important ways. It created uplift and lava which formed new crust. This new crust depressed the Earths crust resulting in the formation of the Lake Superior basin. This new crust has since been weathered and eroded away by processes such as the Huron Creek waterfall which carries and redistributes the sediment downstream.
Common Earth Science Misconceptions:
Misconception: Rivers do not carve valleys, but only passively flow through them.
Combative evidence: At Huron Creek Fall’s there is direct evidence of eroded rock carved by the flowing water. This erosion of the bedrock is still in process at this site.
Misconception: All rocks are the same
Combative evidence: Here the rocks are very different. Even the rock created from the same lava event has differences with in it. The difference in them has helped shape this area.
References:
Rose, Bill. (2012) Earth Science Institute. Available: http://www.geo.mtu.edu/~raman/Silver/MiTEP_ESI-1. Last accessed July 20th 2012
Earth Science Literacy Institute (ESLI). (2009). Earth Science literacy Principles: The Big Ideas and Supporting Concepts of Earth Science. Retrieved from http://www.earthscienceliteracy.org/
Schaetzl, RandallJ,, Joe T Darden, and Danita S. Brandt. Michigan Geography and Geology. New York: Custom, 2009. Print.
Mayer, Alex S. (2009). Huron Creek Watershed Management Plan. Retrieved from http://www.geo.mtu.edu/~asmayer/HuronCreek/HuronCreek.htm