Interpreter’s Notes – Geology Rocks!


Psychologist C.K. Jung said, “A man is not a thing, but a drama.”  Well, a rock is not a thing, but a drama – only existing on the vast scale of geological time.  Pick one up sometime, any rock, and you’ll be holding something that contains the entire periodic table, every known element in the universe.  Is it a metamorphic or sedimentary rock in an igneous environment?  How did it get there?  What’s its story?  They all have a story, the rocks under our feet and all around us, made up of the 5,000 or so substances of the mineral world that make up 90% of the mass and volume of the Earth. 

Geology, simplified, is the study of the Earth’s inorganic substances, its processes and the planet’s history.  But that definition does no justice to this elegant, almost metaphysical science.  Geology reflects the universal axiom of Hermetic philosophy: As above, so below, as displayed by the fact that the mineral substances in the planets and stars above are exactly the same ones inside our bodies and in the ground beneath us (and they are formed in exactly the same way).  One of geology’s major concepts, fromulated by James Hutton in the 18th Century, is called Uniformitarianism, the stipulation that all the laws of the universe have been the same since the beginning of the universe.  To put it spiritually and more poetically, “There is nothing new under the Sun.”  This idea begat today’s science, influencing everything from Darwin’s thinking to modern physics, prodding the concept of the universe as a “closed” system – all the matter and energy in the universe has existed since the beginning of the universe, and there is only a transfer from one state to another.  In other words, matter cannot be created or destroyed, only transformed.  Geology is the great unifying science of the world, the eye of the needle all other sciences do, at some point and in some way, pass thru – astronomy, art, linguistics, paleontology, physics, biology, philosophy, medicine, chemistry, religion, agriculture, anthropology, sociology, meterology, geography, mathematics, climatology, economics … on and on goes the list.

Cape Ann is an extraordinary geological area and Halibut Point State Park is a great place to see that for yourself.  Here are some surprising facts about the geology of Cape Ann: Of the 5000 or so mineral substances that make up the vast majority of the mass and volume of the Earth, two, Annite and Danalite, were discovered on and primarily exist around Cape Ann.  Annite, named after Cape Ann, was first identified in Rockport.  You can learn more about Annite here.  Danalite, named after geology professor J.D. Dana, was initially identified at a Rockport Granite Company quarry in the 19th century.  This link gives you more information about Danalite and this Wikipedia excerpt will tell you more about Professor Dana, one of the foremost figures in the history of geology.

But that’s far from the end of the surprising facts about the geology of Cape Ann.  Here’s something many are astonished to learn:  Cape Ann is considered the third most active geological area in the United States.  The most active geological area is the San Andreas fault, we all know about that one; the second is the New Madrid fault in Missouri, where the largest known earthquake that has happened since Europeans settled the continent occured in 1800.  It was an earthquake so massive that the Mississippi River ran backwards for almost an entire day!  After those two areas comes Cape Ann.  The largest earthquake known to have taken place in New England  happened on Cape Ann in 1755.  That large quake, knocking down walls and chimneys of over a hundred buildings in Boston, was felt from Nova Scotia to South Carolina and over five hundred miles east at sea.  You can take a look at this document on file at the Massachusetts Historical Society to find out more about an event that profoundly affected the New England populace, as evidenced by the no fewer than twenty-seven sermons, poems, and accounts published in the following months featuring, to quote the Massachusetts Historical Society, “such titles Earthquakes the Works of God and Tokens of his Just Displeasure (by Thomas Prince) and The Duty of a People, Under Dark Providences, or Symptoms of Approaching Evils, to Prepare to Meet their God (by Eliphalet Williams).” 

If you’d like even more evidence of how geologically active Cape Ann is, check out this story from USA Weekend magazine, or this one from the Boston Globe, or have a look at this article in American Heritage.  If you want to see a charting of some of the long list of earthquakes that have happened on and around Cape Ann, just go here.  Better yet, click on this extraordinary map, “Earthquakes In and Near the Northeastern United States, 1638-1998” from the US Geological Survey.  If you go to websites such as Microsoft TerraServer or Google Earth you can see some of the unique features of Cape Ann’s geology.  One of them you’ll notice is that the land beneath the region’s feet is so riddled with faults that it looks like a cracked windshield!  Just what exactly makes Cape Ann’s geology so active and so noteworthy?  That’s a longer story than a version of Notes should detail, but some clues are contained in the photographs published below this posting’s heading.  Geology is a science best savored in the field, away from the classroom and all that Godwana-Laurentia-Pangaea/continental rifting/plate tectonics talk we initially experience in school when exposed to the subject.  Yes, there’s a place for all that, but there’s so much to see around us to spur curiosity in this profound, graceful science and Halibut Point is a spectacular place to experience it.

The last version of Interpreter’s Notes promised an explanation of how Cape Ann granite achieved its unique 160lbs. per cubic foot density.  Briefly – at the end of the last great Ice Age, about 15,000 years ago, retreating glacier scraped many millions of years of sedimentary rock off the massive bedrock of granite that today makes up most of Cape Ann.  The bedrock granite, under the pressure of sedimentary rock for so long, became evern more compressed than it was, and once the glacier scraped the surface sedimentary rock away, it left the granite close to the surface.  There may be granite of similar of greater density elsewhere, but most of it, never having had the benefit of such a staggering force of as a mile high mountain of ice to bring it near the surface, remains far under the ground where it cannot be mined.  If you look above at the center photograph under this posting’s heading you can clearly see the striations on the smoothed boulder, tracking north/northwest to south/southwest that was made by the retreating glacier.  Such evident examples of the last Ice Age exist all over Halibut Point, especially in the park’s “scablands” – the still existing grassy balds not far from the Babson Farm Quarry.        

In Herman and Nina Schneider’s classic, Rocks, Rivers, and the Changing Earth: A First Book About Geology the author’s do a remarkable job of connecting the subject to their reader: “The fresh, crisp apple that you may eat today is as old as the hills.  And when you eat it, a tiny bit of those hills become you … Just think of what that apple may have been before it became part of you!  Once it may have been in the autumn leaves that fell and crumbled into the soil near the sprout of an apple tree.  Years before it may have been in the shell of a robin’s egg.  And once it may have been a part of a stalactite in some dark underground cavern.  Perhaps for a short while it flew high above the earth in a butterfly’s wing.  Long ago it may have been in a kernel of corn planted by some ancient people.  Today, when you eat that apple, these parts of the earth become part of you who are part of the world.”    

How wonderfully they state it!


4 Responses to “Interpreter’s Notes – Geology Rocks!”

  1. 1 Chris August 9, 2007 at 5:38 pm

    What a great article!
    I can hardly wait to visit and listen in person to your stories.

    I was searching the web for geologic info on Halibut Point (for a library patron) and came across this.

    Your writing is inspirational.

    I was unable at first to verify the authenticity of the author. It took a little more searching to link this with John Ratti. I would recommend that you include your information “this is a blog of Park Interpreter John Ratti and include your e-mail address” on this page.

    Nice article.

  2. 2 Jan Gill March 6, 2008 at 1:44 pm

    I am doing some research for a project on the geological history of the Cape Ann area, and this artlicle was a great start. Are there progrmas currently running that I could take part in?


  3. 3 Jan Gill April 10, 2008 at 5:26 pm

    Hi John,

    I traveled up to Halibut Point last weekend. What a beautiful place. I am gathering information for a presentation that I am doing on April 28th on the Geological History of Cape Ann. Not having a science or geology background, I am learning quite a bit as I research, but there is still so much to learn. Are there any programs that will be offered before the end of April that may help me understand the history of this area better? Any information you provide would be appreciated!!


  4. 4 Jan Gill April 16, 2008 at 2:12 pm

    Hi John,

    I will be coming up to Halibut Point on Saturday. Will you be in the visitor center? I was hoping we could chat for a bit regarding the geology of the area. What would be a good time to visit?


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