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geo directory

Some of these questions must be answered by consulting your textbook which correlates with the video series.  Consult: "Physical Geology -Earth Revealed" by Carlson, Plummer and McGeary; published by McGraw Hill, New York City, NY


Quiz #4  Review

You may want to review Chapter 17 (groundwater), 19 (glaciation) and 20 ( waves, beaches and coasts)
and the appropriate video episodes:

Long Island  with it's geologic formations:  Upper Glacial, Magothy, Raritan Clay and Lloyd Sand  are important in the context of groundwater.  There are few resources for learning about groundwater related to Long Island.  "Long Island Groundwater: an Environmental View", written in 1973 by your illustrious teacher of Geology, was one of the first books on groundwater systems and can still be found in most Long Island Public Libraries (usually in the historical section!)  The funds from the book (surprisingly, many people bought the book) helped to fund a lawsuit against Suffolk County back in 1973-1974. Suffolk County  was about to embark on a major building program of sewage treatment systems.  Unfortunately, unlike cesspools, those systems would discharge millions of gallons of treated effluent into coastal waters and would have caused salt water intrusion since groundwater pressure would not be sufficient to keep the saltwater out of the groundwater system.  I think it would have been a disaster.  The County got as far as building the massive Southwest Sewer District but because of political scandle and cost over-runs, extension of the system was abandoned by the late 1970's.

Later, in the 1980's, Ray Corwin, who now heads the Pine Barrens Commission, brought over a huge map and we  poured over it on my living room floor in Flanders and we carefully sketched out the preliminary boundary of what would become  the 40,000 +  acre Long Island Pine Barrens Preserve.   The purpose was to put a pristine wilderness in public ownership so that the pure water occupying the thickest part of our groundwater reservoir would stay pure.  Backed by governmental entities and civic groups and sponsered by Steve Englebright, a geologist from Stony Brook who is also a New York State legislator, the preserve was created in the early 1990's.

We spoke in the class about the sand and gravel of the Upper Glacial having great porosity (can contain the most water in the pore spaces) as well as permeability (it's easy for it to become polluted because water flows through it easily).  So even though it holds the greatest amount of fresh water, outside of the pine barrens, it is rarely used because of pollution from fertilizer, pesticides, road salts, landfills and waste dumps.  It's nice to know that under the pine barrens is a large quantity of pristine water that can serve the future.  There are unique problems in regard to groundwater under the north and south forks of Long Island, in that the surface catchment area (to gather and allow rain and snowmelt to infiltrate) is rather small.  The result is, a need to be cautious about overuse of the groundwater.  Recharge basins or "sumps" are mandated by law if land is going to be covered by pavement so that water can still recharge the aquifer.  Landfills have been closed and capped because our groundwater system is our sole-source aquifer.  Aquifers store water, aquacludes do not.  The Raritan Clay is an aquaclude.  We do have artesian conditions in many areas on Long Island, which means that the water in a well will rise above the water table.  Some artesian wells are "free-flowing".

I don't envy those who live in a Karst area and who get there water supply from the ground.  Karst topography is a surface where limestone has been altered by solution (carbonic acid in rainfall and groundwater) to the point where there is cave development, sinks or sinkhole depressions (sometimes from the collapse of caverns) and disappearing rivers (they flow into the sinks).  Named after a region in Eastern Europe, we have similar regions in the U.S. (Parts of Virginia, Kentucky, Alabama, Florida, Texas, New Mexico, Pennsylvania, Missouri, South Dakota and other places where there is limestone which is or was being dissolved by groundwater.)  In the Albany, NY region there is a karst region.  People throw there dead animals and garbage down sinkholes and will often allow their sewage line to discharge into the surface cracks in limestone;  water and this waste it carries flows into the sinks and through the passages in the limestone and sometimes into a well that other folks are pumping out their supply of  drinking water.  It may be miles away, but groundwater flow is usually rapid and unlike sand aquifers, contaminants are seldom filtered naturally!  Cave exploration is known as spelunking and cavers who study caves are studying speleology.  One of the most exciting times I've had as a geologist is scrambling into "wild caves" or dropping down "bottomless pits", which are often relatively unexplored.  Essential for spelunking, is to link up with a cave organization that has access to these caves through landowner agreements and can help you to learn how to cave safely and with respect to the cave (the National Speleological Society has a NY City Grotto or Group that caves upstate.)  The minimum equiptment that you need is a hardhat and several sources of light to carry with you.

The caves of Florida are mostly at or within the zone of saturation. They are flooded: sinkhole lakes through much of central Florida can allow divers access into a cave network.  Other caves where the land has raised or the water table has lowered are in the zone of aeration.  Those caverns can contain speleothems that form as water containing dissolved calcite from the limestone above evaporate and produce crystals of calcite that may accumulate to form stalactites (hang from ceiling tight), or stalgmites (rise from floor with might).  They may join to form columns or along the wall of a cave, flowstone may form.  There are many kinds of speleothems that form in limestone caves.  Also, there are some unusual caves that form in rock gypsum and as lava tubes in basalt flows.

Glaciation:  You already know about Long Island's Pleistocene past,  glacial moraines resulting from continental glaciers (such as the Wisconsin Glacier).  The Harbor Hill Moraine extends from the north shore to Orient, Plum Island, Fishers and to Rhode Island.  The Ronkonkoma extends from the middle of LI to Montauk, then to Block Island and to Martha's Vinyard and Nantucket.  These moraines where they are eroded by waves along the shoreline generate the sand which is deposited as beaches, barrier island, spits, bay mouth bars and tombolos here on Long Island.  South of the moraines of till are the outwash plains of stratified drift.  Occassionally, one will see these huge boulders which look out of place and were transported by the glacier.  These erratics are common along the north shore.  Kettle holes are formed when chunks of glacial ice left over by the retreat of the glacier are buried in outwash and then melt.  One can see these along Sound Avenue not far from our classroom.  There is a very large kettle hole on the campus of the Eastern Campus.  Vernal ponds, important for the rare tiger salamander, are kettles that flood with a higher spring water table and dry up in the summer when the water table falls.

North of Long Island, deposits were laid under the ice sheet which were later exposed as the ice receded with a warming interval.  Drumlins are streamlined hills oriented north and south in the direction the ice moved, Kames are small rounded hills, Eskers are meandering ridges of till (or drift) that are believed to be the sediment- filled tubes left by glacial streams flowing within or at the base of the glacier.  Meltwater was always flowing into the ice sheet by way of cracks called crevasses.  Striations are glacial scratches caused by rock gouging into rock as the rocks are transported by the ice.

Valley glaciers or alpine glaciers form above the snowline which can be at the surface at high (polar) latitudes and at high elevation near the equator.  The snowline has increased in height as the climate has warmed and a result is that even in the high Rocky Mountains of the U.S., glaciers are rapidly disappearing.  To see alpine glaciers go to Alaska or the Canadian Rockies- but hurry!  Glaciers flow from the zone of accumulation (where it snows) to the zone of wastage (where they melt).  On the way they gouge out (erode) a U shaped valley unlike the V-shape of a typical river eroded valley.  Where a basin is carved out on the upper reaches of a mountain where the mass of ice accumulated at high elevation there is the cirque.  When there are cirques left by 3 or more alpine glaciers at the top of a mountain, a horn can be formed (like the Swiss Matterhorn).  Where two glaciers moving down the side of the mountain carving out valleys and an eroded "knife edge" remains where the valley sides meet, there is an arete.  There are also cols, hanging valleys, lateral and medial moraines associated with alpine glaciers.

Waves:  mostly wind generated (tsunami waves are seismic sea waves;  tidal waves are caused by the gravitational pull of the moon and sun).   A wave on water has a crest and a trough, water particles with in the wave moves in circular orbits, waves "touch bottom" at one-half the wave-length which marks the surf zone, where the wave begins to break.  Water is thrown foreward within the surf-zone.  Sand is transported by wave swash, and backwashed as the water rolls back down the beach face to meet the next incoming wave.  The swash and backwash within the surf zone is longshore current and is responsible for transporting sand along the shoreline.

Streams can act as a source of sand the beach is made of, eroded headlands can also be a source of beach sand.  Most of our sand on the north shore is derived from the erosion of the headland or necks (where the Harbor Hill Moraine sticks out into the LI Sound), along the south shore sand comes from, in part, the erosion of Montauk (take note Paul Simon).  Waves bend or refract to converge on any projection of land into the water.  Efforts to save Montauk Lighthouse by preventing the erosion of the Ronkonkoma Moraine may be limiting the sand available to maintain south shore beaches.  Depositional features include sand bars, bay mouth bars, spits, beaches, barrier islands (miles long, narrow and separated from the mainland by a long body of water) and tombolos (connects island to mainland-remember Napeague).  Rocks at Montauk include metamorphic kinds rich in garnet and magnetite.  Sand derived from these rocks make up the dark colored storm deposits seen on winter beaches on Long Island.  Quartz is the #1 component of beach sands and gravel on both our shores.

A notable break (caused by the hurricane of 1938) along the south shore barrier island is Shinnecock Inlet.  The inlet is stabilized by the building of a pair of jetties (otherwise it could easily reclose as sand builds as spit across the opening)  The barrier island formed further out at sea than it is today.  The barrier island has migrated landward with a rising sea-level.  This eustatic change (the sea has risen due to melting glacier ice 300 feet since glaciers stood along our north shore), causes waves to break higher against the barrier island and cause sand to overwash, sand is taken from the ocean side and washed over onto the bay side.  As sea level rises the barrier island is pushed north (in the case of Westhampton Beach and Fire Island.)  The sea is presently rising at a rate of 12" or so per 100 years but that may accelerate as global warming creates an accelerated melting of the remaining glacial ice.

When the coast is eroded, bluffs or scarps are prominent.  Sand is removed.  At the bluffs along the north shore, sand is being removed and at the base of the cliffs one finds pebbly beaches with cobbles and boulders.  Away from the bluffs are depositional bars (transported by longshore currant) and finer sand.  Erosion by winter storm waves can sometimes create a scarp by removing sand from a berm (supratidal part of the beach).  The intertidal part of a beach is the beach face.

A submergent coastline is flooded by a rising sea-level (the east coast of the U.S).  When river valleys are flooded they become estuaries (Chesapeak Bay), when glacial valleys flood they become fiords (Coast of Maine).  An emergent coast is rising from the waters (the west coast of the U.S.) because of tectonic forces.  The U.S. Pacific Coastline has a number of very beautiful actively eroding headlands and well as sandy beaches.  Some of the coast is depositional, some is erosional.

Some lab related material that may be on the quiz:
ore minerals can be used to economically extract a resource from- mostly in association with "metal ores", examples are:  Iron Ores (hematite, magnetite, limonite), Lead Ore (galena), Copper Ore (chalcopyrite, azurite and malachite), Zinc Ore (sphalerite), there are others.

Know the relationship between some sedimentary and metamorphic rocks such as:
sandstone- quartzite
bituminous- anthracite
shale- slate
limestone- marble

I'm probably leaving out some material.

Well, Read the book, read your notes (did I say notes- as in taking notes in class?)...Study.  Get a better grade than on Quiz #3!