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Roger Weller, geology instructor

wellerr@cochise.edu

Boulders
by Nathan Riesgo
Physical Geology
Fall 2009
         
  

Boulders
 

            Across the world and the United States many giant rock formation are causing mouths to drop because of incredible amazement just from their size.  A boulder is nothing but a giant rock… giant? Now how big can giant be? In many cases and most cases one thinks of the biggest rock as the imagination allows. There are three classes of rocks that surround our planet giving most people in “awe” due to the certain beauty of some rocks to chat about.  In reality a boulder is merely a rock 10inches in diameter. Although to the sizes of boulders there is no size limit the unlimited size, a few shocking monstrous rocks has made the record books. Over time a rock may become more incredible for many reasons which is more of a reason to be in “shock and aw” by what our world creates for our eyes to see. In years past Indians used boulder structures for their guides and included them in their everyday lifestyle, which are still proof of that in certain areas.
 

            The three classes of rocks are igneous rocks, sedimentary rocks and metamorphic rocks. Igneous rocks are created below the earth’s surface as it is started as magma also known as a melted rock; a melted rock that cools from the inside slowly cools from melted to a solid becomes a rock. Sediments are fragments found at the bottom of lakes, rivers, or the sea that consist of shells, stones, or plants which are forced together forming a solid rock. Metamorphic rocks are created by the heat and intense pressure beneath the earth’s crust causing a igneous or a sediment rock to be morphed to other minerals and shapes (Ricciuti, Carruthers P.14, 15).
 

            A boulder is nothing but a big rock in its class of size. There are many sized rocks separating them from each other making them their own unique formation. From smallest to largest; the smallest rock starts at clay, silt, sand, granule, pebble, cobble and finally boulder. Clay is much fined talcum powder such like mud being able to roll and make shapes and balls or one’s own style rocks. Silt, is rough but small enough to not see any other particles in it. Sand is multiple grains visible to see other colors and shine from lighting. Granules are the sizes from one forth of an inch to one eighth of an inch (1/4”in. – 1/8”in.). Pebbles are a size small enough to be able to be picked up by ones fingers. Cobble is bigger; cobbles are about a size to have to be picked up by a hand. The boulder is the most interesting unlimited size from picking up with two hands to infinite diameter is the miracle. The starting size for a boulder is ten inches in diameter ("Boulder"; Weller). The biggest boulder in the world is recorded at seven stories high and 5,800 square ft. in Landers, California (LaGrange).
 

            So many amazement of just how a rock is formed has brought so many together to research more and more of what happens to a rock over time. Overtime weathering causes many things to change on its physical features turning its appearance to a more “pretty” outfit on it. Such thing as physical weathering is a physical breakdown without any change in its primary chemical structure, meaning it may be caused to break down into smaller rocks. Chemical weathering is a change of appearance due to the different changes of weathering such as sand blasting or erosion and leaching from the sun and rain wear and tear (Weller).
 

            Boulders are used in many different ways and have been used to its fullest potential from days beyond our time. To this day boulders are used in landscaping, and most often in stream channels. In a river channel boulders are used as a habitual improvement for the animals (Fischenich, Seal). Now, beyond our time, Indian reserve parks have proof of how Indians would use boulders as their guides to where their homes were. Also they were used as a canvas for their pic-art to tell their stories. Rock formations of a balancing boulder are the biggest shock, from how these huge rocks can sit so still. Balancing boulders are located all around the world in New York, New Jersey, Connecticut, Rhode Island, New Hampshire, Massachusetts, and personal proof found in a small town St. David, Arizona at the Dragoon Mountain Ranch (Welcome to Dragoon).
 

            On November 2009 a personal hike let me to a perfect sight of rocks the size I could never imagine. Many boulders seemed to be place in its position on purpose but it just did not seem logical. These were boulders way larger than the possibility of man moved. Boulders that showed chemical weathering due to sandblasting with numerous “dimples” implanted into the rock formation, leaching showing the erosion from chemical changing and especially Indian art drawing. This remarkable location proved the amazing structures that rock formations turn metamorphose to or how they are place as they are all formed. 
 

    

 

 

 


 

 

Works Cited

"Boulder." Wikipedia, The Free Encyclopedia. 17 Aug 2009, 05:14 UTC. 22 Nov 2009
        
   http://en.wikipedia.org/w/index.php?title=Boulder&oldid=308425520

            Fischenich; Seal. "Boulder Cluster and Rock Riffels." . 20 Nov. 2009
            http://projects.geosyntec.com/npsmanual/Fact%20Sheets/Boulder%20Clusters%20&%20Rock%20Riffles.pdf
            LaGrange, Barbara. "The Intrigue of Giant Rock." High Desert Star newspaper Feb 2000. . 20 Nov. 2009
            http://www.lucernevalley.net/giantrock/
            Ricciuti, Edward ; Carruthers, Margaret W.. National Aunubon Society First Guide: Rocks and Minerals . New York, NY: Scholastic Inc., © 1998.

"Welcome to Dragoon Mountain Ranch." Nord Enterprises, Inc.. © 2009. Dragoon Mountain Ranch Homeowners Association. 18 Nov. 2009                http://dmrhoa.net/dmrhoa/page.html

Weller, Roger. Virtual Geology Museum . 20 Nov. 2009. 20 Nov. 2009
           http://skywalker.cochise.edu/wellerr/aawellerweb.htm