Cape Cod Geology- Reprint of an earlier Post [Archive] - Fly Fishing Forum

: Cape Cod Geology- Reprint of an earlier Post


striblue
05-25-2004, 09:53 AM
A couple years ago I posted this thread and thought I would repost it in case anyone is interested in this facinating subject. This was posted on the Striper Board.

"I wanted to take this opportunity to recommend a great book entitled, " A Geologist's View of Cape Cod", by Arthur N. Strahler. It is a paperback and costs $7.95 for the 110 pages it contains. It is published by Parnassus Imprints, Box 335, Orleans ,MA. 02653. I purchased my copy at one of the book stores in Chatham but suspect that it can be found in any of the other bookstores on the Cape. Without providing a detailed book report, the table of contents reveals the following subject matter, " How Cape Cod was formed"; " What the waves have done"; " What the Tides have done"; " Ponds and Bogs of Cape Cod"; What the wind has done", and finally ," The soils of Cape Cod".The final chapter discuses the future of the Cape in Geological terms. The Book includes approximatly 60 illustrations, photographs, charts, and topographical mapes which visually explain the narration. There is also a list of further reading if one wishes to get into great "academic" detail. In any event, I wanted to point out a few issues it clarifies and explains which make this interesting and facinating reading for the non-scientists amoung us.

1)The Cape did not exist before the last ice age(Wisconsin stage). The zone was the present day continental shelf which was a dry plain.As the ice sheets spread, the farthest point south where it finally stopped in our area was Martha's Vinyard and Nantucket. You can see this today from the finger ponds and rivers on the south shore of the Vinyard which were created by Glacial till and flow of the ice melt. The second line of ice retreat was approximatly at the location of the mid-cape highway. The two large Ice sheets were known as the South Channel lobe, which ran along the lower cape, and the Cape Cod lobe which ran to the islands and then to the mid-cape. These two lobes were part of the massive glacier called the Laurentide Ice Sheet which covered most of North America.

2)The Book goes on to explain the melting away of the ice sheets which deposited the land matter it carried (glacial pluck). As it melted it created rivers of water and mud. These rivers are still there today on the south shore of the cape. The melting also produced outwash which formed the land itself. The sea level rose to the point of the highest outwash levels. Today , at nauset beach and elsewhere along the national seashore you can see Bolders(e.g. To the left of the beach from the parking lot), which fell off of the cliff scarps and probably originate from somewhere in Maine.

3) Two Interesting explainations are discused. Today you can still see scrapings on large bolders. These scrapings, called "glacial striations", show how the rocks came in contact with other bolders and bed rock(At parts to the north of the cape itself, since the cape has no bedrock), as they traveled in the glacial pluck. Enos Rock in Eastham and the bolders at the Naust coast guard station are examples plainly seen today. The second interesting point is the formation of the Kettle ponds(which are generally common knowledge, but just the same...). As the ice melted over the millenia huge chuncks of ice broke off the glacier and as water, till and outwash flowed from the main glasier, it would hit the chunks and deposit the material at and around the ice block. The flow would depost this material up to ,and at times, over the ice block . As the ice block melted the pond would form and the sides would collapse over the centuries. In fact , at the bottom of these ponds,you could dig a couple of feet down and reach the ancient surface ( Ground Zero). The book then goes on to describe the knob and Kettle landscape and the plains of Eastham, Truro and Wellfleet.

4) As the sea rose the ancient shore line of the cape was irregular and evidence of this shore line can be seen today as the western shore of Pleasant Bay,, Oyster pond, Orleans(at town Cove), Wellfleet harbor, and much of the Hyannis shore line.. As the waves and wind sculptured the eastern shoreline of the cape,and the sea flooded approximatly 2 to 3 to 4 miles of land to the east of Nauset, Wellfleet and Truro beaches and "hanging Valleys" appeared. Hanging valleys are evidence that the land had reached out substantial to the east. These valleys are where the present "hollows" are as well as other areas. They are valleys ,such as the Pamets rivers, which can be seen to end abruptly at the back of the huge dune cliffs that front the beaches. They were formed from Glacial outwash of the South channel ice lobe which flowed toward the bay side. The Chapter then goes on to describe incoming wave action, parts of a beach, marine scarps,storm wave errosion and wave refraction.

5) Another interesting discussion centers around beach drifting and the longshore current. For example, at Wellfleet on the ocean side the current splits into two directions, one south and one north. The north current formed the Provincelands and Race Point. The southern current formed Nauset beach and Monomoy Island. There is a description of Sand Bars and Sand spits. Monomoy is continuing it's march southward, infact, during the period between 1856 and 1868, as a result of violent weather patterns during that period,Monomoy Point was extended southward at a rate of 157 feet per year. There is discussion of Tombolos,And the growth of the Provincelands. An interesting point to note is that the ancient shoreline to the north actually ended approximatly a couple hundred feet south of Pilgrim lake at a place called "High Head". From that point north, including P-Town itself, Race Point and the Provincelands formed from Beach drift flowing northward. You can see all of this by going to High Head today and get a feel for what has transpired over the millenia, and look down from that hill and know that you are standing on the original "beach".

6) Finally there is descriptions of Tide activity and what that has contributed to mud flats and salt marshes, A description of ground water, when fresh water meets salt water, The cranberry bogs, Wind and Parabolic dunes, leaping sand grains, ventifacts and general soil composition.


Obviously, massive changes will not occur during our life times or that of our children or our children's children. Only the occational change similar to what happened to the beach infront of the Chatham Light or that description of Monomoy growth ,or the break between north and south Monomoy. Ah, but if I've got you hooked now and you want to know what the author says about the "geological" future. He says that what will happen is........"

Greg Pavlov
05-25-2004, 04:35 PM
Obviously, massive changes will not occur during our life times ...


One thing that a lot of us have noticed is that Nauset Beach in Nauset appears to have shrunk quite considerably in the last 5-6 years. Is this a cyclical thing ?

rooster
05-25-2004, 04:59 PM
I think the glaciers tried to return to New England this past winter, based on comments from my buddies at the Springclave!
See you sssssoooon!
DK

juro
05-25-2004, 05:17 PM
Fascinating read John! I will have to read Mr.Strahler's book. Puts more meaning into each step to have that perspective.

kush
05-25-2004, 05:42 PM
John,

Do you want to come and be a guest speaker in my grade 12 Geography class? Strahler authored a couple of my university texts (both of which I still use). In fact I have a topo map of the Cape on my classroom wall that I ostensibly use to illustrate the the glacial features you nicely explain - as well as the longshore drift processes.

:devil: - but you know the real reason it is there is so I can remember the cool fishing I had while at the Cape and dream of my next visit!

seuss
05-25-2004, 08:11 PM
On a separate but somewhat related note, i recently had the opportunity to tour the Cold Regions Research and Engineering Laboratory (CRREL) up in Hanover, NH. Some very interesting things going on in that facility. Not the least of which had to do with their extensive ice core research.

Turns out, contrary to what the popular media would have you believe, the ice core data (which goes back many thousands of years) clearly indicates we're on the verge of the next ice age. Frankly, the graph freaked me out.

Yet another reason to get out there and fish while we still can. And/or make sure that engine on your ice auger is primed and ready for action.

Nick
05-26-2004, 07:01 AM
Sounds like a great read...i'll have to pick it up next time I'm on the Elbow.

Ice9
05-26-2004, 10:50 AM
If the ice age does arise, somebody e-mail me and let me know and I'll spread the word up here.

Ice
(in Minnesota)

PS Strahler's book is on sale at Amazon used as low as $2.

D

striblue
05-26-2004, 12:20 PM
Suess is right, according to the time frames studied we are at the beginning stages...so Ice9.... We will have a few thousand years, give or take ,to stay in New England while it is building up in Minn.;)

Ice9
05-26-2004, 12:44 PM
May not take that long...this past winter lasted at least six hundred years, and it's still going...can't wait to hit the cape next week and warm up to 60 and fog.

dave

striblue
05-26-2004, 01:42 PM
Where will you be on the Cape???

Ice9
05-26-2004, 02:43 PM
I'm a part of the Mark Frondorf outfit...smallmouth buides from the DC area, but I moved to Minnesota where fishing is pure self-defense. We arrive Weds. night and fish out of Orleans until the following tues--that's 6/2-6/8 or so. Maybe we can hook up and fish.

dave

striblue
05-26-2004, 03:59 PM
OK..great, Mark has already contacted me so I look forward to seeing you.

Greg Pavlov
05-26-2004, 04:40 PM
Originally posted by Ice9
May not take that long...this past winter lasted at least six hundred years, and it's still going...can't wait to hit the cape next week and warm up to 60 and fog.
Sounds like there are going to be an awful lot of us decending next week. I've been looking forward since the day I was last there, last Sept :-)