Archive | August, 2013
August 21, 2013

On the Way Home: The Black Hills

There are six national parks within the Black Hills area of South Dakota and Wyoming.  And, along with six parks comes a lot of different things to do!

 

Devils Tower

Devils Tower is our country’s first national monument.  It is an ancient volcano in the eastern part of Wyoming – it is officially part of the Black Hills along the South Dakota border.  Rain and ice has created vertical columns in the mountain, giving Devils Tower its unique look.  These columns are still subject to erosion and some of them will break off from time to time.

How did it get the name “Devils Tower”? Well, back in 1875 when it was first discovered, the members of the expedition misinterpreted the name given by American Indians.  They thought American Indians called it “Bad God Tower” – when in reality the Lakota called it “Bears Lodge.”  Devils Tower was pretty intriguing, however, and so the name stuck!  Devil’s Tower was the vey first US National Monument – President Theodore Roosevelt declared it a monument in 1906.   Today, thousands of rock climbers come to Devils Tower each year -    some actually make it to the top!

 

Crazy Horse 

Crazy Horse Memorial is in the Black Hills – it is a memorial to the Native Americans who used to call this land home.  The Crazy Horse statue is part of the memorial.  Crazy Horse was a real person – he was a Lakota warrior.  Eventually, the statue will show him on his horse, pointing off into the distance.

An American sculptor named Korczak Ziolkowski designed the sculpture and started work on it in 1948.  Before that, he worked on Mount Rushmore.   Mr. Ziolkowski passed away in 1988, but left over 30 detailed plans and models – his wife and children are continuing the project.

Work has been going on for about 60 years and it is not finished yet!  In fact, only Crazy Horse’s face is completed.  And, work is beginning on the horses head.  When it is completed (IF it is ever completed), it may be the largest sculpture in the world – longer than a cruise ship and higher than a 60-story skyscraper!

The Crazy Horse Memorial is operated by a nonprofit organization – the sculpture is paid by donations from the general public and visitor fees.  In addition to the statue, the Memorial is home to the Indian Museum of North America and the Native American Cultural Center.

 

Caves

Many people go to the Black Hills to go spelunking – that is a fancy word for cave exploring.  Jewel Cave is one of the longest caves in the world – there are over 150 miles of underground passageways!  Some of its walls are lined with jewel like crystals (called calcite crystals).  What formed all those crystals? Well, a long time ago the water around the cave was acidic and dissolved the limestone rock it came into contact with.   Eventually that limestone was deposited on the walls of the cave.  Jewel cave also has many other calcite formations that are common to caves – stalactites, stalagmites, flowstone and frostwork.

Wind Cave is another cave system in the Black Hills – in fact, it was the very first cave in the world to be designated as a national park.  It is known for its boxwork – it contains 95% of all boxwork known in the world.  But, what is boxwork?  Well, boxwork is unique within the cave world because it is formed from erosion rather than deposits – it is made of calcite that does not erode as fast as the wall or ceiling of the cave.  Over time, as the wall or ceiling erodes away, what is left is a design of calcite strands zig zagging every which way.

Wind Cave can be very windy!  It has only a few small openings – so the air circulation process common to all caves can be magnified at times.  In general, air is constantly moving in and out of caves, in order to equalize the air inside the cave with that outside (atmospheric pressure, for you young scientists).  When a cave has a lot of openings, this happens almost without us knowing it.  But, when there are few openings, the process is obvious and the cave seems almost to “breathe” – with air rushing in and out.

 

Badlands National Park

Visiting the Badlands National Park is like stepping into another world – like maybe the moon!  The landscape is peculiar and there is no sign of civilization anywhere.  The unique rock formations in the Badlands have been sculpted from many years of erosion by both wind and water.  There are deep gorges, sharp spires, steep gullies, fat buttes, pinacles and pyramids.

What makes the Badlands different?  Well, erosion happens more rapidly in the Badlands than most other places on earth.  That is because the conditions are just right – kind of like the Bermuda triangle for erosion.  First, the ground has more sediment, clay and sand than hard rock (like granite).  Second, there is little rain – which makes the soil dry.  Third, there is little vegetation to hold down the soil.  Fourth, erosion over the years has created steep slopes in the land.  Add an infrequent, but intense rain to these factors and you have the opportunity for massive erosion!

 

Dinosaur Digs

Dinosaurs used to roam through the Black Hills!  And, we are talking about the big guys – tyrannosaurus rex, triceratops, brontosaurus and stegosaurus to name a few.  During those dinosaur days, the whole area was a savannah, with lush grass and trees that provided foods for some of those big huge animals.

After the dinosaur period, the whole great plains was covered in a shallow sea.  The floor of that sea hardened into a rock called shale, which is found all over the Badlands.  This shale fossilized all kinds of interesting bones – dinosaurs and more.  The fossils in the Badlands are evidence of some pretty unusual animals that lived long ago – sabre tooth cats, ancient camels, and three toed horses are just a few.

And, don’t forget the wooly Mammoth – mammoth bones are still being found today in the Black Hills.  In fact, the fossils of more than 56 mammoth have been found in a huge sinkhole – the Mammoth Site of Hot Springs.  These fossils are young compared to those of the dinosaur – only 26,000 years old!

Prehistoric bones are still discovered today.  In fact, you can even go on a dinosaur dig if you visit the Black Hills.  There is Dinosaur Park in Rapid City.  There is also: Wyoming Dinosaur Center, Paleo Park, and the Mammoth Site.

 

Goldmines

The Black Hills used to be part of the Wild West – with gunfights, buffalo hunts, cattle drives and its own gold rush.  Overnight, mining towns appeared all through the Black Hills in the late 1800’s.   Most people panned for gold in the streams and rivers of the Black Hills hoping to “strike it rich”!

Gold is a metal that exists naturally in the earth.  Scientists think that most of the earth’s gold is contained in its core – particles of gold and other metals were floating in space when the earth was formed.  But, that gold can’t be mined.  Most of the gold that we mine in the earth’s crust was deposited by asteroids thousands of years ago.  Very small particles of gold are usually embedded in rock – sometimes a layer of gold is found, which looks like a “vein” running through the rock.

How does the gold get into the streams?  Well, its all about erosion (again!).  As wind and water erode the rocks and mountains of the area, tiny particles of gold can break free.  Since gold is dense and heavy, it tends to collect on the bottom of stream beds.  Sometimes these tiny particles of gold will find each other and bond together, eventually creating a nugget of gold.  This is what people look for when they sift through the streams with their “pan.”

Most gold mines in the Black Hills are long gone, but there are still some places where you can take a look at an old underground gold mine and try your hand at panning for gold – like the Broken Boot Gold Mine, for example.

August 13, 2013

The Terraces of Mammoth Hot Springs

Mammoth Hot Springs has terraces of steaming pools – it looks almost like stairs going up the hill!  In fact, there are over 50 hot springs in the Mammoth Springs area.  The terraces are hydrothermal features, similar to the geysers, mud pots, hot springs or fumaroles that we talked about earlier.

The heat source that created Mammoth Hot Springs is the same as the other hydrothermal features in the Park – the “hot spot,” or super volcano.  In addition, Mammoth Springs has the same water source – rain and snow (it has an underground connection to the Norris Geyser Basin, allowing it to exist even though it is technically outside the caldera).  Further, the same plumbing system exists in Mammoth Springs as well – cracks in the rocks that allow water and steam to escape.

What makes Mammoth Springs different is the presence of limestone and hot gas.  Huge, thick layers of limestone rock are beneath the Mammoth area.  In addition, there are hot gases rising from the magma deep in the earth.  As water seeps into the earth, it comes into contact with these hot gases.  Carbon dioxide is dissolved into the hot water, making it acidic.

This hot acid-water dissolves some of the limestone as it flows up through the rock, creating a solution called calcium carbonate.  When this solution reaches the hot springs and is exposed to the air, the particles all separate again.  Carbon dioxide dissolves into the air and the limestone particles attach to the sides of the hot springs.  Over time, these deposits of limestone created the white mountains of travertine that we see.  It sounds like one big science experiment, doesn’t it?

Mammoth Hot Springs is one of the few active travertine terraces in the world.  Every day, the hot water bubbles up and deposits limestone particles on the terraces.  As a result, Mammoth Hot Springs is constantly changing – for example, the Opal Terrace deposits one foot of travertine every year.  If your parents visited Yellowstone when they were younger, the terraces probably look very different from what they remember!

 

August 4, 2013

The Petrified Forest

Yellowstone National Park has the highest concentration of petrified trees in the world (there are more in Yellowstone than almost anywhere else on earth).   What is a petrified tree?  Well, it is a tree that is buried after a volcanic eruption – usually the trees are covered in a combination of volcanic ash and hot mud rivers called “lahars.”

 

It is thought that the petrified trees in Yellowstone were buried in volcanos that erupted about 40 million years ago (a different one from the last huge Yellowstone eruption that created the Yellowstone caldera).  Research has shown that, over the years, over 20 volcano eruptions occurred in the area, each creating its own collection of petrified trees.

Most of the petrified trees in Yellowstone were redwoods, as well as other conifers like pine and fir, and even some maple and oak trees.  Some trees are so well preserved that you can still count their rings and figure out their age – some were over 1,000 years old when they were petrified!   The petrified trees in Yellowstone are unique in that they are still standing upright (most petrified trees are laying on the ground).

The Fossil Forest is a little secret gem inside Yellowstone – there are few trails to the area with the highest concentration of trees.  Most people look at them from afar by visiting “Specimen Ridge.”  You can view “The Petrified Tree” up close in the northeast part of the Park, near the Lost Lake Trail.  But, no souvenirs please!

Many people may not know it, but Yellowstone is home to more than just fossilized trees – over the years, scientists have found fossilized plants, leaves, and even a few fish and reptiles.  Many of these fossils are located al the way across the country from Yellowstone – at the Smithsonian Museum in Washington DC.