Thursday, September 1, 2016

Minecraft-worthy Geology In The Wrack Line At Sandy Hook, NJ – Part 5 of 5: Coal and Tarballs

                                                          Coal; Jetty rock w oil

Coal

Chunks of coal, as well as slag from burned coal and smelted iron, are found in the bay and ocean wrack lines at Sandy Hook.

Coal had been an important source of heat in public buildings and power plants until the late 1960’s. Most of the coal washing up on the beach came from spillage from ships, or from dumped “cellar ash”. Some of it may be from “sea coal” carried along the coast from rivers in the Appalachian coal fields and from the Valley and Ridge province long before it was mined. It was abundant enough on Long Island beaches that a permit was issued in 1677 to locate significant deposits.

With more pressure, heat and time, peat transforms into lignite, bituminous, and eventually, anthracite coal. Most coal was formed in peat or coal swamp forests (scroll down to The Coal Age) about 300 million years ago during the Carboniferous Period:

Coal forms from the accumulation of plant debris, usually in a swamp environment. When a plant dies and falls into the swamp, the standing water of the swamp protects it from decay. Swamp waters are usually deficient in oxygen, which would react with the plant debris and cause it to decay. This lack of oxygen allows the plant debris to persist.” When this layer of peat is buried by sediments, the weight “compacts the plant debris and aids in its transformation into coal. About ten feet of plant debris will compact into just one foot of coal.”

Some chunks may also be lignite deposits from the Raritan-Magothy Formation where it outcrops along Raritan Bay in Middlesex County. Recently formed peat from tidal flats and salt marshes can also be seen in the wrack line after storms, and cedar peat deposits have been found in cores of the seafloor a few hundred feet off coastal lakes in Monmouth County. Here are more pictures of peat, lignite and coal; scroll down for a picture of peat with clam borings found on a beach in Long Island.

Tarballs

While most coal was formed from peat swamps about 300 million years ago, oil and natural gas were formed from plankton, most of it from 252 to 66 million years ago.

Black round tarballs from oil spills from refineries along Raritan Bay and oil tankers can periodically be found in the wrack line at Sandy Hook. About 21 billion gallons oil transported by marine tankers passed under the Verrazano Bridge in 2010, as reported in “A Stronger, More Resilient New York” (p134, pdf-p 4).

Scientists from the University of Utah have calculated that it takes 98 tons of these buried prehistoric plants to produce a single gallon of gasoline. They also found that the amount of fossil fuel burned in one year is equivalent to "'all the plant matter that grows in the world in a year,'" including vast amounts of microscopic plant life in the oceans.”

Volcanoes were a major source of the carbon dioxide in the atmosphere during the period of geologic time known as “Greenhouse Earth”. A superplume caused by abundant volcanoes produced 4000 ppm of carbon dioxide and other greenhouse gases that melted the icecaps during the Cretaceous and put the NJ coastline between the Watchung Mountains and Rt 1 (scroll to Figure “Generalized geographic map of the United States in Late Cretaceous time”).

Currently, carbon dioxide produced by fossil fuels is about 130 times present volcanic emissions, but just one tenth of the catastrophic super-plume levels of the Cretaceous.

Widespread scientific consensus exists among scientists that are experts in the field of climate studies that the world’s climate is now changing (NASA) faster (NOAA) due to burning so much of these plant-derived fossil fuels.

The other four blogs are at http://pehealthnj.blogspot.com/ .


Minecraft-worthy Geology In The Wrack Line At Sandy Hook, NJ – Part 4 of 5: Jetty Rocks


T(l-r): Basalt/Diabase, Mica Schist, Gneiss
B(l-r): Limestone w Stromatolites, Pumice, Scoria 

Jetties are mostly volcanic rocks like basalt and diabase - not obsidian!

Obsidian is a sought-after block in Minecraft that forms when magma rapidly cools in air or water. There's no obsidian or volcanoes at Sandy Hook, but most of those dark gray boulders in the jetties were also formed by volcanoes (slide 20).

Like obsidian, diabase is formed from magma in the earth's crust, while basalt is formed from lava, which is magma that has flowed to the earths surface.

Basalt and diabase were formed as the supercontinent Pangaea started breaking apart, according to the theory of plate tectonics. The Appalachian Mountains and Anti-Atlas mountains that are now in Africa were once a single range higher than the Himalayas (Gallagher, 2003). NJ shared a border with Morocco about 245 million years ago!

When Pangaea started rifting apart about 200 million years ago, lava formed into the basalts of the Watchung Mountains, the pillow lava (Figure 94) of the Orange Mountains, and the Great Falls in Patterson). Diabase cooled into the columns of the Palisades. The water surrounding Pangaea rushed in to fill the rift between the new continents, creating the Atlantic Ocean (Gallagher, 2003). A lot going on in the back-story of those bland jetty rocks and the gravel in your driveway.

Basalt and diabase are also used as traprock and gravel are mined in the Piedmont province of NJ. Chunks of the jetties worn smooth as sea glass can be found in the wrack line.

Other Jetty Rocks

Schist and gneiss boulders like those found in the Highlands province of NJ can be found in jetties at Sandy Hook or in the seawall extending to Sea Bright that was built by the Army in 1898 (scroll down for rock pictures). Several boulders of light gray mica schist can be seen among the darker basalts in the jetty protecting the road along Horseshoe Cove south of Parking Lot K. When pieces are found in the wrack line they look like this.

Parts of the granite seawalls the Army built around the tip of Sandy Hook in the 1890s to protect the gun batteries still line the shoreline of the freshwater pond past Nine Gun Battery near North Beach. Granite in NJ is from the Highlands province (map, p. 1)

Limestone boulders that could be half a billion years old from the Valley and Ridge province (start at slide 37) are also in the seawall near the entrance to Sandy Hook. The chalky white boulders that formed from shells accumulating in warm shallow seas stick out among the dark, volcanic basalts in the seawall near the steps from the Highlands Bridge. Some have banded swirls that may be fossils of stromatolites - the Earth's oldest fossil (3.7 billion years old) - that gradually changed the “atmosphere from a carbon dioxide-rich mixture to the present-day oxygen-rich atmosphere” 2.5 billion years ago.

Other Volcanic Rocks

Other volcanic rocks in the wrack line more likely washed up from a storm-flooded landscaping project rather than from drifting in on the Gulf Stream from a Caribbean volcano. Pumice (scroll down for picture) looks like quartz but is much lighter, almost airy; when you break it open you can see crystals similar to obsidian. The unusual foamy look comes from being rapidly cooled and depressurized after it is ejected from a volcano. Scoria forms from cinder cones around volcanoes and is used to make lightweight concrete.

Bedrock

The gneiss and schist like the boulders found in the jetties and seawall make up the bedrock (pdf-p 21) beneath the aquifers of the coastal plain in NJ. They are metamorphic rocks formed from shale and sandstone and are found in the Highlands province of NJ. (The Wanaque Tonalite Gneiss is part of an outcrop that runs from Wanaque to Ringwood with the oldest rocks in NJ - 1.35 billion to 1.37 billion years old.

In Monmouth County, this “basement rock” lies about 700 feet below sea level, beneath the deepest aquifer in Sandy Hook, the Potomac-Raritan-Magothy (map). Bedrock is more than 1500 feet below sea level in Manasquan, and over a mile deep in Cape May (map on pdf-p 19 ).

Selected References

Forman, Richard (Ed.). 1998. Pine Barrens: Ecosystem and Landscape



The other four parts of this blog are at http://pehealthnj.blogspot.com/ .

Minecraft-worthy Geology In The Wrack Line At Sandy Hook, NJ – Part 3 of 5: Iron, Sandstone and Quartz


T(l-r): Peanut Stone, Sandstone, Iron slag 
B(l-r): Gardeners Clay, Quartz

Peanut Stone: Iron-Cemented Sandstone and Quartz

Sandstone, iron, and quartz are all found in a local sandstone that looks like chunks of peanut brittle in the wrack line.

“Peanut stone” is a quartz-studded ironstone of limonite formed 11-9 million years ago (slide 3) during the Tertiary period.

It is part of the Cohansey sand formation near the top of the Mount Pleasant Hills across the bay From Sandy Hook (the Cohansey sands extends south through the Pine Barrens and becomes the largest water-table aquifer in NJ).

The peanut stone is the caprock of the ridgeline that has prevented the Mount Pleasant Hills from washing away to flatlands like most of the Bayshore. At 266 feet, Mount Mitchell in Atlantic Highlands is the highest point south of Maine directly on the coastline. During the last Ice Age (the Pleistocene Epoch) this ridgeline may have been “... as high as 600 feet above (ancient) sea level ...”.

Locals have been using peanut stone since the 1880's to build chimneys, walls, the Dempsey house in Leonardo, the Stone Church in Locust, and the stone bridge over Grand Avenue in Atlantic Highlands.

Ironstone used to be mined and smelted in Monmouth County for its iron ore. “European settlers mined bog iron in local streams” for its iron ore “to produce utensils, such as plows and axes, and cannon balls for the American Revolution.” Ubiquitous and slimy iron bacteria produce a floc in streams and seeps in Monmouth that resembles Acid Mine Drainage, and an iridescent rainbow sheen that mimics oil spills.

The first iron works in NJ was constructed around 1674 in Tinton Falls. The industry peaked after
the war of 1812 until about 1844, when transporting coal and richer ores of iron from
Pennsylvania became more cost-effective (Forman, 1998).

Chunks of iron slag from iron smelting are scattered like small meteroites in the bay and ocean wrack lines at Sandy Hook.

Much of the other sandstone and clay concretions washing up on the beach are from Sandy Hook . The surface of Sandy Hook is very young, only about 3-4000 years old (see Holocene Deposits), but it rests on sediments that are more than 250 feet deep. They may have began accumulating after the peak of the last Ice Age 25,000 years ago, when the Atlantic coastline almost reached the Hudson Canyon, about 100 miles offshore today.

They are also from submerged barrier beaches that developed from 12,000 to 7,000 years ago when sea level was lower (see Holocene Deposits). Small shells and other “neofossils" can often be observed in “chunks of well cemented beach sand, displaying bioturbation and marine fossils, [that] are eroding from these submerged barriers”, that are as near as a few hundred feet offshore.

The oddly molded chunks of Gardeners Clay (Figure 148A) that washes up on the ocean beaches after storms has been found in sediment cores at Sandy Hook near Spermaceti Cove (pps. 29-31) as well as beneath Long Island. Gardeners Clay is a glauconitic, foraminiferal marl and sand that was formed in an ancient bays.

Quartz

The peanuts in peanut stone are quartz, which is the most common pebble found on the beach.

Quartz is the second most abundant mineral on earth (after feldspar), and is found throughout NJ in igneous rocks like granite, sedimentary rocks like sandstone, and metamorphic rocks like schist and gneiss.

Sand is made of fragments of rocks and minerals including quartz. Quartz can be found in all four provinces in NJ, but originally eroded from the Appalachian Mountains (p. 142). The Beacon Hill Gravel that formed 9-7 million years ago at the top of the Mount Pleasant Hills has been called “essentially the same” as the “modern gravel deposits on Sandy Hook”.

The different colors in quartz are caused by the chemicals present while it is crystallizing from molten magma. Colors include citrine, rose quartz, amethyst, smoky quartz, and milky quartz. The rust-stain common in the quartz pebbles in the wrack line is from the iron in the soil or groundwater.

Selected References

Forman, Richard (Ed.). 1998. Pine Barrens: Ecosystem and Landscape

The other four parts of this blog are at http://pehealthnj.blogspot.com/ .


Minecraft-worthy Geology In The Wrack Line At Sandy Hook, NJ – Part 2 of 5: Glauconite


On the beach, glauconite looks like pale green quartz but feels noticeably lighter.

It's nicknamed the “drinking water stone” at Sandy Hook because water entertainingly disappears into its pores.

It is a mineral found throughout Monmouth County and other parts of the Coastal Plain province in clay, silt and sand - not the lithified, stony formation on the beach.

Depending on its acid and clay content, it is nicknamed greensand, marl, poison marl, rotten stone, or hardpan.

It is actually a green to black silicate of iron, potassium, and phosphorous that formed millions of years ago from the droppings of sediment-dwelling invertebrates in the shallow shelf regions of Cretaceous and Tertiary seas. Its potassium content made glauconite a widely used as a soil conditioner in Monmouth County after Peter Schenck started using it on his farm in 1768 near aptly named Marlboro (Forman, 1998).

Glauconite makes up much of the Navesink Formation at the base of the Mount Pleasant Hills, a ridgeline (and major watershed divide) that begins in Hartshorne Park in Middletown by Sandy Hook Bay, and crosses NJ all the way to Delaware Bay in Salem County.

The glauconitic clay in the Navesink and other formations near the bottom of the Mount Pleasant Hills occasionally interact with the overlying sands to produce landslides or “slump blocks” in Atlantic Highlands and Highlands (p. 22). Sometimes when heavy rainfall rapidly percolates through the sand at the top of the hill, water builds up on the impervious glauconitic clay until the heavy, saturated block of sand - and anything on it - slides over the marl and down the hill (pictures, pps. 14-21).

The Navesink Formation was formed about 70 million years ago when Sandy Hook was beneath more than 150 feet of shelf water. The carbon dioxide and other greenhouse gases that helped melt the icecaps (and set up the dinosaurs for extinction) during the Cretaceous period were from a superplume caused by abundant volcanoes.

Back then, the Atlantic coastline was between the Watchung Mountains and Rt. 1; scroll to the map “Generalized geographic map of the United States in Late Cretaceous time”. (Rt. 1 in NJ more or less follows the geologic boundary between the the rocks of the Piedmont province and the sandy outwash of the Coastal Plain known as the Fall Line.)

The first dinosaur discovered in North America, the duck-billed dinosaur, Hadrosaurus foulkii – our state dinosaur - was discovered in 1858 as a result of marl-mining at a farm near Haddonfield, NJ. (Forman, 1998).

About 20 miles southwest of Sandy Hook, a black marl outcrop of the Navesink Formation (picture, p. 11) towers over Big Brook in Colts Neck, where fossil enthusiasts can shell-pick 70 million-year-old oyster shells and other marine species right from the streambed.

Greensand is one of the oldest types of water treatment used to remove heavy metals from drinking water, including radium, and is used medically to speed up the elimination of internal radionuclides (Table III, p. 9).

Selected References

Forman, Richard (Ed.). 1998. Pine Barrens: Ecosystem and Landscape

The other four parts of this blog are at http://pehealthnj.blogspot.com/ .


Minecraft-worthy Geology In The Wrack Line At Sandy Hook, NJ – Part 1 of 5

Now I get it. Those busloads of school kids looking for, of all things, obsidian, as well as shells at Sandy Hook are what the New York Times is calling the Minecraft Generation.

Minecraft is a video game released in 2009 that allows players to build things out textured cubes in a 3D generated world that is now the second best-selling video game in the world.

But its not just virtual Lego. It's now commonly used in schools to “increase kids’ interest in the “STEM” disciplines — science, technology, engineering and math”. Its fans are awaiting a new “Minecraft: Education Edition” that will be released this fall.

One of the sciences children learn about in Minecraft is geology - so effectively that the governments of Sweden, England and Scotland have developed programs that allow players to use local geology while they are playing Minecraft.

There is plenty of Minecraft-worthy geology at Sandy Hook too. You can walk along its ocean and bay beaches and see rocks from all four geological provinces in NJ. The next four parts of this blog will help you prepare for your #deeptime #geowalk – along a timeline from a few thousand to over half a billion years old.

Part 2: Glauconite



Part 3: Iron, Sandstone and Quartz



Part 4: Basalt and Diabase, Schist, Gneiss, Granite, Limestone, Pumice, and Scoria


Part 5: Coal and Tarballs


The other four parts of this blog are at http://pehealthnj.blogspot.com/ .