Part 4

Control of Atmospheric O2

Organic carbon is buried, which is rich in electrons (reduced), moving more electrons out of the atmosphere and therefore increases the O2 (oxidized). Atmospheric CO2 and O2 behave in opposite ways.

Three Primary Formations of Mammoth Cave

1. The St. Louis 2. The St. Genevieve 3. The Girkin

Causes of Breakdown

1. Water no longer fills the cave removing the buoyant force, allowing material to fall 2. Solution of joints frees a block causing it to fall 3. Sagging of the limestone beds 4. Wedging effect of mineral growing in fractures

Red Granite and Baraboo Interval

1.7 Ga, post-penokean. Includes rhyolite, baxter hollow granite (beneath Baraboo q

Penokean

1.8 Ga intruded migmatized Gneiss by Penokean tonality dike with xenoliths

Biwabik-Gunflint Iron Formation

1.9 Ga, source of first Precambrian Microfossils

Sinkholes in MCNP

Form near surface as dissolution of underlying rocks causes sediment to fall into excavated holes formed in the calcareous rock

Solution Sinkholes

Form when water dissolves the surface rock, creating a depression.

Guadalupe Escarpment

Formed by an exhumed barrier reef that developed around the perimeter of the Delaware Basin during the Permian. The reef formed the Capitan Limestone and contains many reef creature fossils.

Precambrian Microfossils

Found in Biwabik-Gunflint Iron formation, composed of phototrophs (an oxygenic and oxygenic)

Gowganda Glacial Diamictite

From the Huronian Glaciation in Southern Ontario, 2.3 Ga.

Phreatic Zone

Fully saturated region at the water table

Moraine Damming

Glacial till from re-advance of glaciers creates dam

Oxidation and Glaciation

Great rises in O2 in the atmosphere are inducing factor of glaciations

Stages of Water Table in Carlsbad

Greatest exchange of sulfides occur at and above the water table but diminishes within the phreatic zone.

Sulfuric Acid Cave Formation Equation

H2SO4 (sulfuric acid) + CaCO3 (limestone) + 2H2O = [CaSO4x2H2O (gypsum)] + CO2 + H2O

Granitoid Gneisses

Highly metamorphosed rock in Voyageurs NP. Were derived from high-silica rocks, possibly volcanic origin an sandstones

Kettles Lakes

Ice sheet leaves behind ice chunks in the moraine and outwash, leaving depressions behind when the ice chunks melts. Resulting lakes are usually small, often having steep sides.

Glacial Rebound

Ice sheet puts pressure and wight on crust, pushing it down, after ice melts crust raises back up

Stalactites

Icicle like structures that form hanging from the ceiling of the cave and grow slowly is water drips over them. Slow drips

Ground Water at the Water Table

In direct contact with the atmosphere, which allows for greater exchange of CO2

Green River

Incised to lower and lower elevations with various pauses for extended periods of time during the Pleistocene Epic, which allowed cave networks to develop associated with water table height at specific times.

Sudbury Meteorite Impact

Occurred at the end of the Gunflint Iron Formation deposition. Created quenched melt blebs from impact on the rocks, 1850 Ma

Why are small particles easier to move?

Small particles have cohesion and hide in the viscous sublayer

Suspended Load

Small particles like silt and clay that are held in the water column by turbulence

Nuna

Supercontinent in part assembled by the Penokean Orogeny.

1.2%

Surface and freshwater make up _____ of Earth's water

Natural Entrance

Surface eroded and met the surface of the cavern

Water Table

Surface that separates a zone where the ground is fully saturated with water, from the region where the pore spaces in rocks are not fully saturated with water.

Surface water in karst topography

Surface water doesn't form streams usually flows right into sinkholes

Alluvium

Unconsolidated sediments, which have been eroded, reshaped by water in some form

River Equilibrium

Unique slope at which water discharge can balance sediment transport

Speleothems

Various intricately shaped formations that grow in caves by the accumulation of dripstone

Superior Province

Voyageurs and Isle Royal are in this portion of the Canadian Shield. This region is a large Precambrian sub region with many bedrock exposures

Fastest, slowest

Water at the top moves the _____________, while water at the bottom moves the _________________.

Top Water

Water at the top rides on the water below it and therefore moves faster

Why are all landscape depressions not lakes?

Water drains, in some places water drains more quickly than it enters a basin

Anatomy of a Meandering Stream

1. Thalweg 2. Point bar 3. Cut bank

How Lakes Gain Water

1. Precipitation 2. River input 3. groundwater discharge

How Lakes Lose Water

1. River outflow 2. Groundwater recharge 3. Evaporation

Ice-Scour Lakes

- Most northern lakes on bedrock - made when glacier scrapes up the rock

Types of Speleothems

1. Stalactites 2. Stalagmites 3. Flowstones 4. Columns 5. Etc

Reef Formations

1. Submerged resistant mound or ridge formed by accumulation of plant and animal skeletons 2. Form in shallow, warm water. 3. Sediments are mainly composed of calcium carbonate (lime).

Types of Lakes

1. Tectonic a. Graben b. Earthquake 2. Glacial a. Ice-scour b. Moraine damming c. Kettle d. Mountain cirque 3. Volcanic a. Crater 4. Others a. Solution b. Riverine c. Reservoirs and beaver dams

Features of Carlsbad

1. 107 miles of cave mapped, 3rd longest in U.S. 2. Cave temperature is 56F year round which is the mean surface temperature 3. Most caves inactive as water below depth of caves 4. Climate is semiarid so karst features missing (not considered karst topography) 5. Unique geometry of large interconnected rooms with irregular patterns and profiles 6. Contains deepest cave in US at 1593 feet 7. Most caves formed in phreatic zone

Types of Bedrock Erosion Process

1. Abrasion 2. Plucking

Types of Rivers

1. Alluvial Rivers 2. Bedrock Rivers

Morton Gneiss

1. An Archean-age migmatitic gneiss found in the Minnesota River Valley 2. Oldest rock unit in the United states, 3.4-3.5 Ga 3. "Rainbow Gneiss" 4. Type locality is in Morton, Minnesota

History of Voyageurs

1. Archean Basement Complex - Highly metamorphosed rocks dated to 2600 MA (pre-Konoran) 2. Kenyan Orogeny and End of Archean - Emplaced large granitic batholiths in the superior Providence and brought about intense folding and uplift causing mountain ranges and metamorphism of older rocks 3. Dikes were intruded (2100 MA) 4. Prolonged erosion throughout Paleozoic, Mesozoic, and Cenozoic. End of Precambrian brought an end to the deformation in Canadian Shield. Only roots of mountains remained. 5. Pleistocene glaciations

Capitan Reef

1. Boarded by an apron of reef talus that merges with fine grained limestones deposited in deeper waters 2. Is largely what makes up caves in Carlsbad

Channel Patterns

1. Braided river 2. Transitional 3. Meandering river

Cave Formation

1. CO2 comes from atmosphere or gasses stored in soil as biological material decomposes 2. Groundwater becomes acidic after interacting with CO2 3. Interaction of acidic groundwater with calcareous rock, like limestone or dolomite, and dissolves rock 4. Dissolution leaves behind empty pockets that develop into caves

Cave Formation in Carlsbad

1. Caves formed by upward movement of sulfuric acid 2. Sulfuric acid likely formed by oxidation of H2S gas derived from regional petroleum fields 3. Most caves have up-down dissolution of weak carbonic acid - Carlsbad is unusual

Stream Order

1. Characterizes the stream basin. 2. Order referee to the number of 1st order segments upstream from a given reach 3. High order streams are more important

Types of Entrainment

1. Dissolved load 2. Suspended load 3. Bed load

Gypsum Deposits in Carlsbad

1. Extensive gypsum deposited in cave, some are 20 ft thick 2. Most of gypsum precipitate on cave floor comes from sulfate rich brine that once filled cave 3. Mineral called Endellite found, which forms in a sulfate rich environment. 4. These features suggest that sulfuric acid played role in cave formation

Dissolution Equation

1. H20 + CO2 ->H2CO3 (carbonic acid, can disassociate) <-> H+ + HCO3- 2. CaCO3 (calcareous rock) <-> Ca2+ + CO3-2 (carbonate) 3. H20 + CO2 + CaCO3 -> Ca2+ +2HCO3-

Flow Types

1. Laminar 2. Turbulent

Penokean Orogeny

1. Mountain building event 1.8 - 1.9 Ga. Evidence in Baraboo Quartzite and Cambrian/Ordovician Carbonates 2. When most of basement of WI made 3. Covered by Paleozoic rocks in southern Wisconsin 4. Penokean Volcanic Massive Sulfide (VMS) deposits, xenolith-bearing Penokean granite, deformed early Penokean granitoid

When Lake Inputs are Greater Than Outputs

1. Open basin lakes, excess water can drain 2. Closed basin lakes, water level rises

Huronian Glaciation

2.3 Ga

Great Oxidation Event

2.3-2.5 Ga, the change of Earth's atmosphere from reducing to oxidizing, brought about by oxygen-generating photosynthesis. Stemmed from organic carbon burial on new continental shelves from break up of supercontinent Kenorland. Sets stage for eukaryotes to evolve.

Typical Superior/Marshfield Gneiss

2.7 Ga, found in Cambrian and Ordovician Sandstones

Aquifer

A body of permeable rock that can contain or transmit groundwater

Migmatite

A high grade metamorphic rock formed when gneiss is heated high enough so that it begins to partially melt, creating layers, or lenses, of new igneous rock that mix with layers of the relict gneiss.

Canadian Shield

A huge, rocky region that curves around Hudson Bay like a giant horseshoe. The Shield covers half the land area of Canada, and some of the upper midwest Contains Archean rocks. Divisible into structural provinces based on rock ages which have a distinctive style of formation

Darcy's Law

A mathematical equation stating that a volume of water, passing through a specified area of material at a given time, depends on the material's permeability and hydraulic gradient.

Craton

A part of the Earth's crust that's been stable for 1500 million years, meaning its felt no orogenic events.

Graben Lakes

A rift or depression is created by moving plates (faulting) and fills with water. These make very deep lakes are some of the oldest lakes.

Laurentide Ice Sheet Movement

Advanced into Minnesota and retreated about 10,000 years ago. Scraped away trees, rocks, and soils eroding down to the bedrock leaving barren land behind and eroded many basins

Gneiss

An intermediate to high grade metamorphic rock that has ribbon like layers, formed at higher levels of temperature and pressure. It was made from other rocks that have been squeezed and heated a long time in the Earth.

Kenyan Orogeny

Archean rocks of Voyageurs associated with this orogenic event, which is the earliest datable orogeny. These rocks date 2600 MA or older

Speleothem Formation

As groundwater in the vadose zone enters the cavern, CO2 is outgassed, causing carbonate to be precipitated out of the groundwater.

Gypsum Flowers

Form as water evaporates and calcium sulfate dehydrate is deposited in the cave

Stalagmites

Form at bottom of cave when water drips quickly off cave ceiling. Fast drips

Pillow Basalts

Basaltic lava that solidifies in an underwater environment

Second Rise in O2

Between Proterozoic and Phanerozoic (.6-.7 Ga, or 750 Ma), set stage for animals (multicellular life). Came from break up of Rodinia, which greatly expanded continental margins, mostly at low latitudes.

Higher, lower

Bigger particles are deposited when the water is moving faster at _______________ elevations, smaller particles deposited as water slows at ________________ elevations

Dripstone

Calcite deposited as dripping water evaporates

Water Table

Caves tend to form near the ________________________

Weathering in MCNP

Chemical content of water indicates cave is dissolving away at 1 mm per year.

Dolines

Close depression in the ground surface, particularly common in areas of limestone or gypsum karst terrain (karst sinkholes)

Minnesota River Valley

Contains oldest rocks in the US, the Morton Gneiss

Laramide Orogeny

Created local uplift that formed, in part, the Guadalupe Mountains, which was accompanied by faulting and southeastward tilting.

Flowstone

Created when water enters the cave and flows as a layer or sheet over a surface and forms a broad and flat deposit.

Abrasion

Debris transported by the stream scrapes against the walls and banks of the channel smoothing it. Causes grooves and river potholes

Delaware Basin

Deep basin in the center of Carlsbad. Carbonate apron between reef and basin, reefs were deposited around the rim.

Thalweg

Deepest part of the river

Point bar

Deposit that forms by accretion on the inner side of river bend

Mammoth Cave Rocks

Deposited in a shallow sea in the Mississipian, on the rim of the Illinois basin, which caused a slight dip of the rocks to the northwest.

Patterns of Deposition and Erosion in Meandering Rivers

Deposition on the inside of the curve and erosion on the outside of the curve

Collapse Sinkholes

Develop by the collapse of material into an underground cavern

Stream Discharge Equation

Discharge = Mean velocity x cross-sectional area

Drainage Basin

Divides separate each basin from its neighbor. Geology usually controls the divide' as they are comprised of material more resistant to eroding.

Bottom Water

Drags on river bed, which slows it

Groundwater Flow

Driven by gravity acting on elevation differences in water height in the vadose zone and both elevation differences and water pressure gradients in the phreatic zone.

Base Level

Elevation of river at its end

Glacial Features in Voyageurs

Erratics, striations, and glacial polish

Groundwater Flow in MCNP

Flow in region moves subsurface to the Green River

Turbulent Flow

Flow that is deep and fast, packets of water are bouncing into each other

Deposition

Flux in is greater than flux in

Balanced

Flux out equals flux in

Erosion

Flux out is greater than flux in

Vertical shafts in caves

Form as groundwater flows down vertical features

Closed Basin Lakes

Lakes with no outflows

Open Basin Lakes

Lakes with outflows

The Big Room

Largest underground cave chamber in North America, one of the largest in the world. It covers 14 acres and floor to ceiling height is 370 feet.

Greenstone Belts

Less highly metamorphosed rock in Voyageurs. Have a dark green color from presence of chlorite, epidote, actinolite, which are produced from metamorphism. Also consists of schistose, meany highly foliated, and sheared lavas that have undergone extensive metamorphism. Some places contain pillow basalts.

Thunder Bay

Location of Sudbury impact tsunami deposit.

Mammoth Cave

Long, winding nearly horizontal tunnels. Subsurface water largely controlled by local geologic structure. Cave has many different levels because as the Green River erode downward, water diverts to progressively lower passages. Caves form mainly in the vadose zone

Jointing in Capitan Limestone

Main control of cave orientations in Carlsbad

Breakdown

Material that fall from roof or walls on the floor of the cave

Dissolved load

Material, especially ions from chemical weathering, that are carried in solution by a stream

Glacial Lakes

Most common type of lakes

Oldest Rocks in Wisconsin

Near town of Thorp, zircons from 3.2 Ga

Vadose Zone

Partially to unsaturated zone at the water table

Spongework

Pores in limestone dissolve open. Irregularly sculpted pattern formed by differential dissolution of acid-rich water

Back Reef Limestones of the Delaware Basin

Prominently bedded and contain a large amount of silt eroded from nearby land areas/

Arid Climate in Carlsbad

Reduced speleothem growth in caves

Plucking

Removal of rocks through hydraulic action or collisions with large clasts which can cause crack growth. Size of the blocks is generally determined by joint or bedding spacing in the rocks.

Bedrock River

River in which the bed and banks are made of bedrock.

Alluvial Rivers

River which the bed and banks are made up of mobile sediment (alluvium)

Drag

River's sides have _________ from river bank walls

Water Flow

Rivers flow from higher elevations to lower elevations, the greater the slope the faster the water flows

Karst Topography

Rock that are 90% more calcareous fully develop into karst topography, which is associated with cave formation. Characterized by underground drainage systems with sinkholes and caves.

Rocks in Voyageurs National Park

Rocks in the park and surrounding region are Precambrian, mostly Archean, in age.

Boudin

Sausage link like formation in the rock, like a piece of taffy being pulled.

Bed Load

Sediment transported close to or along the channel bottom by rolling, bouncing, or sliding

Aggradation

The increase in land elevation due to the deposition of sediment

Cut Bank

The outside bank of a stream, which is continually undergoing erosion

North American Craton

The stable core of the continent is the North American Craton. Much of it was also the core of an earlier supercontinent, Laurentia. The part of the craton where the basement rock is exposed is called the Canadian Shield. Surrounding this is a stable platform where the basement is covered by sediment; and surrounding that are a series of orogenic zones.

What spot in the river is moving the fastest?

The top and center of the stream

Laminar Flow

Thins films of water, smooth flow. Water doesn't bounce into neighboring water paths

Cave pearls

Water drips into small basin with sand particles, particles become coated with calcium carbonate. If they are agitated enough from dripping water, they'll refrain from cementing to floor and create cave pearls, 1 inch in diameter.

Joints, Bedding

Water flows down the paths of least resistance, like _____________ or ________________

Cave Popcorn

Water seeps out of pores in the rock, nodules are precipitated. They are most abundant where capillary water is drawn from the moist rock

Columns

When stalagmites and stalactites connect

Slows, bigger

When water velocity _______, ___________ particles are deposited first

Great Lakes

Where glaciers scoured deep basins from pre-existing valleys with relatively soft rocks

Mesozoic

______________ uplift led to some dissolution and erosion, but not the primary cause

Entrainment

__________________ is easier for sand sized particles