Northwestern Vermont Geoscience Tour
On day
one we will explore three diverse but interesting locations in the
Burlington Vt. area. The ECHO
Lake Aquarium and Science Center is a nice little facility right
on the Lake Champlain Waterfront with a lakeside terrace where you can
have a light breakfast while overlooking the lake with a background of
the high peak region of the Adirondack Mountains. A tour of the
facility reveals exhibits and activities for a broad range of ages that
provide a good overview of the flora, fauna, hydrological,
meteorological, and
geological features that make this region so interesting. The hours of
operation, travel directions and admission fees are shown on the linked
website but the simple directions are to go to the Burlington
Waterfront off Battery street just below the Hilton Hotel. Teachers
with credential ID's get in free so bring one and
save some money. Don't forget to collect your data of meteorological
astronomical and geographical information as described on those pages
of this website, and do your reflective
journal writing of each days activities.
Some specific regional knowledge that will be introduced at this stop includes;
All images above from ECHO website http://www.echovermont.org/
This location is small and tries to present a number of important concepts about the science of our region to a broad range of ages but it serves as a good introduction to some of the topics we will explore in depth as the week progresses. After the tour of the Science center we will return to the terrace for a deeper introductory discussion of the geologic and glacial events that formed the lake over time as well as the other points of interest the science center presented that will resurface as the week progresses. This part of the day will take 2 hours.
Evolution of Lake Champlain.
This is an important area of study so that you will have a better idea of why you will see the types of rocks, landforms and fossils throughout the week. The modern body of water we call Lake Champlain after its European "discoverer" Samuel de Champlain has evolved over time due to the effects of glaciation and was once the Champlain Sea, a paleomarine environment that is the only ocean besides the very ancient Iapetus Ocean that Vermont has bordered. The Vermont State fossil is a type of early beluga whale and evidence of marine reefs and other organisms is widespread throughout the region attesting to our prior marine shoreline environment. The state fossil and other evidence of the paleooceanic environment will be seen on day 2 of this tour when the Perkins museum of Geology at UVM is visited, as well as the Redstone Quarry where marine fossils are found in situ as well as shoreline ripple marks.
During the Wisconsinian glacial stage the Laurentide ice sheet began its retreat from as far south as Cape Cod and by about 12,000 years ago it had retreated to the St Lawrence lowlands north of present day Vermont. The weight of the ice from the Wisconsin event isostatically depressed the Champlain basin below sea level. The northward retreating ice sheet created an ice dam that retained the glacial meltwater creating ancient Lake Vermont. When the remaining ice retreated to the point where the rising Atlantic ocean could flow in, the basin was inundated by more dense salt water creating the Champlain Sea. Eventual isostatic rebound raised the basin and that rise combined with the inflow of freshwater from the surrounding land slowly transformed the Champlain Sea into the present-day, freshwater Lake Champlain. (1,2,3) There is a lot of evidence of glaciation in the Champlain Valley with glacial erratics and glacial till distributed widely in the region including many shoreline locations we will visit. Look for distinctive metamorphic rocks that originated in the Laurentian Mountains of Quebec that are markedly different than the more typical sedimentary rocks of the Champlain Valley. In some areas the oldest glacial striations or grooves in the bedrock are further evidence of the glacial activity of the Laurentide ice sheet and compass measurements of their orientation indicates that the general direction of ice sheet movement was to the southeast riding up and over the Green mountains. Younger striations indicate that at about 14,000 years ago the thinning ice sheet became more directed by the mountains that flank the Champlain Valley. The glacial till material deposited by the glacier in in the present day Champlain Valley is overlain by fine sediments that were able to settle out of Glacial Lake Vermont that was formed from meltwaters of the ice sheet but not allowed to drain north due to the remaining ice sheet which formed an ice dam in what is now the St. Lawrence River Valley. Seasonal freezing of Lake Vermont caused coarser sediments in the turbulent summer meltwater currents to be overlain by the fine sediments in the quieter winter months creating seasonal varves. The ice dam eventually melted to the point where Lake Vermont flooded out to the Atlantic Ocean in a catastrophic flood about 12,000 years ago that dropped the level of the lake an estimated 300 feet. The combination of rising sea levels and isostatic depression contributed to the surface of the Champlain Sea which now occupied the Champlain Valley being 200 feet higher than the present day lake level but 300 feet lower than Lake Vermont. Residual fresh water from Lake Vermont created a less than fully marine body of water in the Champlain Sea. There is evidence of this surface level in the large deltaic river deposits of the Winooski and Lamoille Rivers where they enteres the Sea at the present day locations of the Burlington airport, St. Michaels College and portions of the UVM campus (1).
Field evidence of paleo marine organisms will also be seen on day 4 at the Chazy Reef, and Lessors quarry.
Champlain Overthrust at Lone Rock Point
The second stop on day one will be at The Champlain Overthrust approximately 3 miles north on Battery Street from the ECHO Science center on the grounds of the Burlington Catholic Diocese which grants permission by phone to visit this tremenduous geologic feature on their property. The Diocese property is located behind the Burlington High School off North Avenue at 5 Rock Point Rd, Burlington Vt. (802) 863-3431. This portion of the days trip should take 5 hours incuding travel by car and foot to the site. This site is the first time we will examine Vermont rocks in the field and a great field guide to some of the rocks we will observe during the trip is available through the state natural resource site. No collecting or use of rock hammers is permitted on State land and landowner permission is a courtesy you should request befor collecting on private land.
Steve Kluge http://www.anr.state.vt.us/dec/geo/chthrust.htm
Geological significance of this site.
Vermont has a long history of major geologic events that have shaped the land and this site is perhaps one of the most dramatic. Thrust faults are low angle (<45 degree) reverse faults that place older geologic formations over younger ones and can have large displacement distances. The Champlain thrust fault has a westward displacement between 35 and 50 miles and a throw (vertical displacement) of about 8,850 feet at Lone Rock Point with Cambrian age Dunham Dolostone over Ordovician Iberville shale (7). The events that led to the formation occured during the Taconic Orogeny when the previously widening Iapetus Ocean began to close as a result of a change to an active oceanic-continental convergent boundary from the previous divergent spreading center (6, p204-5).
Image modified from Rowley & Kidd 1981
Image Source: Dr. Ron Blakey Northern Arizona University
This opening and closing is referred to as a Wilson cycle in honor of J. Tuzo Wilson the Canadian geologist who did so much to unify the theory of Plate Tectonics. Some interesting features at Lone Rock Point are a consequence of the tremendous forces of the faulting and the differences in rock types. The more resistant Dunham Dolostone overhangs the weaker Iberville shale and large blocks of dolostone that have broken off are scattered along the shoreline. The Iberville shale has been compressed by the overlying dolostone and has thin layers with numerous calcite veins running throughout but there has not been sufficient heat or pressure to metamorphosize the shale into slate. The boundary between the two rock types is a layer of breccia made of bits and pieces of both rock types. There are many places where the underlying surface of the dolostone is exposed and a wavy series of mullions helps to establish the direction of movement of the thrust fault. You can measure strike and dip very easily using this surface. Make those measurements and note them in your journal. What is the angle of the thrust fault?
www.consrv.ca.gov/.../faults.htm http://www.telusplanet.net/public/nstuart/dips.gif
This region shows evidence of the deposition of deep water shales, siltstones sandstones and carbonate deposits of marine and non-marine origin. The Taconic Orogeny that shaped this area was the result of convergent plate motion where island arcs and microterranes collided with ancestral North America which introduced siliclastic sediments onto the existing carbonate shelf of the area. This was a change from a passive continental margin to an actively subducting one. The plate movements of the Taconic orogeny also changed the shoreline environment which had an impact on the lifeforms of the region. During the early Ordovician Eastern North America was at about 35 degrees south latitude moving north to abot 30 degrees south by the late Ordovician (38). The closure of the Iapetus Ocean created an accretionary prism of ophiolites that can be seen in East Dover Vermont in an ultramafic body composed of serpentines, olivies and other materials believed to have been placed there by tectonic rather than intrusive mechanisms (39).
South Burlington Living Machine Wastewater Treatment Facility
This award winning facility uses the natural processes carried out by plants, animals and microorganisms to treat munincipal wastewater. The facility was designed by a firm in Burlington and has been successful for several years. The site is about 8 miles south of the ECHO science center at 15 Bartlett Bay Road off Route 7 (Ethan Allen Highway) South Burlington, VT 05403 and this portion of the day will take about 2 hours including travel.
www.rps.psu.edu/0009/graphics/machine1.gif www.rps.psu.edu/0009/graphics/machine1.gif
Importance of this Facility
Ecological awareness is important at many levels in Vermont and the ability to treat munincipal wastewater using natural processes rather than chemical treatment reduces our ecological impact. The Living Machine facility was built in 1995 to treat 80,000 gallons of wastewater daily and it has been successful in doing so since that time. The system drastically reduces both chemical and biochemical oxygen demand (BOD & COD) as well as total suspended solids (9). Living Technologies was the local parent company that developed the system and the range of applications continues to grow, solving site specific sewage problems in various locations worldwide.
The general sequence of treatment begins with aeration of the waste stream to provide a good environment for bacteria introduced at this step to begin digesting the waste. Further aeration allows aquatic plants and their associated microorganisms to continue the breakdown. In the next step gravity is used to settle out solids that are removed for composting. Remaining organics are treated by recirculating fixed film reactors (8). This technology has been adapted to larger and smaller applications within and outside the State. Our Local Lake Champlain is the endpoint for treated wastewater from numerous communities and while treated it often carries a higher load of treatment chemicals such as chlorine than facilities such as the South Burlington Living Machine generate. This visit is important in that it demonstrates technologies that reduce the human impact on the environment. Natural processes are typical for many Vermont residences in rural areas that use single family septic systems with leach fields but this application of natural processes in a munincipal setting is a more recent effort to manage waste flow.
Some specific regional knowledge that will be introduced at this stop includes;
- The geologic events that shaped the region including the evolution of the lake boundaries.
- The on-site Rubenstein Ecosystem lab is a University of Vermont research facility that studies many aspects of the lake environment.
- Aquaria with a good selection of regional fauna and flora.
- Informational displays about a
variety of scientific topics pertinent to the Champlain Basin. Native
and invasive species, ecology, geology, climatology etc.
All images above from ECHO website http://www.echovermont.org/
This location is small and tries to present a number of important concepts about the science of our region to a broad range of ages but it serves as a good introduction to some of the topics we will explore in depth as the week progresses. After the tour of the Science center we will return to the terrace for a deeper introductory discussion of the geologic and glacial events that formed the lake over time as well as the other points of interest the science center presented that will resurface as the week progresses. This part of the day will take 2 hours.
Evolution of Lake Champlain.
This is an important area of study so that you will have a better idea of why you will see the types of rocks, landforms and fossils throughout the week. The modern body of water we call Lake Champlain after its European "discoverer" Samuel de Champlain has evolved over time due to the effects of glaciation and was once the Champlain Sea, a paleomarine environment that is the only ocean besides the very ancient Iapetus Ocean that Vermont has bordered. The Vermont State fossil is a type of early beluga whale and evidence of marine reefs and other organisms is widespread throughout the region attesting to our prior marine shoreline environment. The state fossil and other evidence of the paleooceanic environment will be seen on day 2 of this tour when the Perkins museum of Geology at UVM is visited, as well as the Redstone Quarry where marine fossils are found in situ as well as shoreline ripple marks.
During the Wisconsinian glacial stage the Laurentide ice sheet began its retreat from as far south as Cape Cod and by about 12,000 years ago it had retreated to the St Lawrence lowlands north of present day Vermont. The weight of the ice from the Wisconsin event isostatically depressed the Champlain basin below sea level. The northward retreating ice sheet created an ice dam that retained the glacial meltwater creating ancient Lake Vermont. When the remaining ice retreated to the point where the rising Atlantic ocean could flow in, the basin was inundated by more dense salt water creating the Champlain Sea. Eventual isostatic rebound raised the basin and that rise combined with the inflow of freshwater from the surrounding land slowly transformed the Champlain Sea into the present-day, freshwater Lake Champlain. (1,2,3) There is a lot of evidence of glaciation in the Champlain Valley with glacial erratics and glacial till distributed widely in the region including many shoreline locations we will visit. Look for distinctive metamorphic rocks that originated in the Laurentian Mountains of Quebec that are markedly different than the more typical sedimentary rocks of the Champlain Valley. In some areas the oldest glacial striations or grooves in the bedrock are further evidence of the glacial activity of the Laurentide ice sheet and compass measurements of their orientation indicates that the general direction of ice sheet movement was to the southeast riding up and over the Green mountains. Younger striations indicate that at about 14,000 years ago the thinning ice sheet became more directed by the mountains that flank the Champlain Valley. The glacial till material deposited by the glacier in in the present day Champlain Valley is overlain by fine sediments that were able to settle out of Glacial Lake Vermont that was formed from meltwaters of the ice sheet but not allowed to drain north due to the remaining ice sheet which formed an ice dam in what is now the St. Lawrence River Valley. Seasonal freezing of Lake Vermont caused coarser sediments in the turbulent summer meltwater currents to be overlain by the fine sediments in the quieter winter months creating seasonal varves. The ice dam eventually melted to the point where Lake Vermont flooded out to the Atlantic Ocean in a catastrophic flood about 12,000 years ago that dropped the level of the lake an estimated 300 feet. The combination of rising sea levels and isostatic depression contributed to the surface of the Champlain Sea which now occupied the Champlain Valley being 200 feet higher than the present day lake level but 300 feet lower than Lake Vermont. Residual fresh water from Lake Vermont created a less than fully marine body of water in the Champlain Sea. There is evidence of this surface level in the large deltaic river deposits of the Winooski and Lamoille Rivers where they enteres the Sea at the present day locations of the Burlington airport, St. Michaels College and portions of the UVM campus (1).
Field evidence of paleo marine organisms will also be seen on day 4 at the Chazy Reef, and Lessors quarry.
Champlain Overthrust at Lone Rock Point
The second stop on day one will be at The Champlain Overthrust approximately 3 miles north on Battery Street from the ECHO Science center on the grounds of the Burlington Catholic Diocese which grants permission by phone to visit this tremenduous geologic feature on their property. The Diocese property is located behind the Burlington High School off North Avenue at 5 Rock Point Rd, Burlington Vt. (802) 863-3431. This portion of the days trip should take 5 hours incuding travel by car and foot to the site. This site is the first time we will examine Vermont rocks in the field and a great field guide to some of the rocks we will observe during the trip is available through the state natural resource site. No collecting or use of rock hammers is permitted on State land and landowner permission is a courtesy you should request befor collecting on private land.
Steve Kluge http://www.anr.state.vt.us/dec/geo/chthrust.htm
Geological significance of this site.
Vermont has a long history of major geologic events that have shaped the land and this site is perhaps one of the most dramatic. Thrust faults are low angle (<45 degree) reverse faults that place older geologic formations over younger ones and can have large displacement distances. The Champlain thrust fault has a westward displacement between 35 and 50 miles and a throw (vertical displacement) of about 8,850 feet at Lone Rock Point with Cambrian age Dunham Dolostone over Ordovician Iberville shale (7). The events that led to the formation occured during the Taconic Orogeny when the previously widening Iapetus Ocean began to close as a result of a change to an active oceanic-continental convergent boundary from the previous divergent spreading center (6, p204-5).
Image modified from Rowley & Kidd 1981
Image Source: Dr. Ron Blakey Northern Arizona University
This opening and closing is referred to as a Wilson cycle in honor of J. Tuzo Wilson the Canadian geologist who did so much to unify the theory of Plate Tectonics. Some interesting features at Lone Rock Point are a consequence of the tremendous forces of the faulting and the differences in rock types. The more resistant Dunham Dolostone overhangs the weaker Iberville shale and large blocks of dolostone that have broken off are scattered along the shoreline. The Iberville shale has been compressed by the overlying dolostone and has thin layers with numerous calcite veins running throughout but there has not been sufficient heat or pressure to metamorphosize the shale into slate. The boundary between the two rock types is a layer of breccia made of bits and pieces of both rock types. There are many places where the underlying surface of the dolostone is exposed and a wavy series of mullions helps to establish the direction of movement of the thrust fault. You can measure strike and dip very easily using this surface. Make those measurements and note them in your journal. What is the angle of the thrust fault?
www.consrv.ca.gov/.../faults.htm http://www.telusplanet.net/public/nstuart/dips.gif
This region shows evidence of the deposition of deep water shales, siltstones sandstones and carbonate deposits of marine and non-marine origin. The Taconic Orogeny that shaped this area was the result of convergent plate motion where island arcs and microterranes collided with ancestral North America which introduced siliclastic sediments onto the existing carbonate shelf of the area. This was a change from a passive continental margin to an actively subducting one. The plate movements of the Taconic orogeny also changed the shoreline environment which had an impact on the lifeforms of the region. During the early Ordovician Eastern North America was at about 35 degrees south latitude moving north to abot 30 degrees south by the late Ordovician (38). The closure of the Iapetus Ocean created an accretionary prism of ophiolites that can be seen in East Dover Vermont in an ultramafic body composed of serpentines, olivies and other materials believed to have been placed there by tectonic rather than intrusive mechanisms (39).
South Burlington Living Machine Wastewater Treatment Facility
This award winning facility uses the natural processes carried out by plants, animals and microorganisms to treat munincipal wastewater. The facility was designed by a firm in Burlington and has been successful for several years. The site is about 8 miles south of the ECHO science center at 15 Bartlett Bay Road off Route 7 (Ethan Allen Highway) South Burlington, VT 05403 and this portion of the day will take about 2 hours including travel.
www.rps.psu.edu/0009/graphics/machine1.gif www.rps.psu.edu/0009/graphics/machine1.gif
Importance of this Facility
Ecological awareness is important at many levels in Vermont and the ability to treat munincipal wastewater using natural processes rather than chemical treatment reduces our ecological impact. The Living Machine facility was built in 1995 to treat 80,000 gallons of wastewater daily and it has been successful in doing so since that time. The system drastically reduces both chemical and biochemical oxygen demand (BOD & COD) as well as total suspended solids (9). Living Technologies was the local parent company that developed the system and the range of applications continues to grow, solving site specific sewage problems in various locations worldwide.
The general sequence of treatment begins with aeration of the waste stream to provide a good environment for bacteria introduced at this step to begin digesting the waste. Further aeration allows aquatic plants and their associated microorganisms to continue the breakdown. In the next step gravity is used to settle out solids that are removed for composting. Remaining organics are treated by recirculating fixed film reactors (8). This technology has been adapted to larger and smaller applications within and outside the State. Our Local Lake Champlain is the endpoint for treated wastewater from numerous communities and while treated it often carries a higher load of treatment chemicals such as chlorine than facilities such as the South Burlington Living Machine generate. This visit is important in that it demonstrates technologies that reduce the human impact on the environment. Natural processes are typical for many Vermont residences in rural areas that use single family septic systems with leach fields but this application of natural processes in a munincipal setting is a more recent effort to manage waste flow.
| Day 2 |
Day 3 |
Day 4 |
Day 5 |
Day 6 |
Day 7 |
Met data |
Geogr. data |
References |
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