Cape Cod
By: Mallory Otten and Amelia Pillar
General Geologic History
Cape Cod is a feature on the coast of Massachusetts formed by glacial activity, more specifically, the Laurentide ice sheet. The Laurentide ice sheet reached its maximum 20,000 to 25,000 years ago and moved across the area of Cape Cod 23,000 years ago (Martin, Laurentide Glaciation of the Massachusetts Coast). Cape Cod formed during the more recent years of the Pleistocene Epoch (which makes up one million to ten thousand years ago), during the Wisconsin Age, which occurred 50,000 to 70,000 years ago (Skehan, Roadside Geology of Massachusetts). Cape Cod was at the edge of the ice sheet advance, and the ice sheet stayed in that position long enough for an end moraine to develop. Because the speed of the advancing ice was not constant, three ice lobes were responsible for forming Cape Cod (Skehan, Roadside Geology of Massachusetts). The Buzzards Bay lobe formed the upper cape, the Cape Cod Bay lobe shaped the middle cape, and the South Channel Lobe influenced the eastern and lower cape (Strahler, Geologist's View of Cape Cod). Glacial deposits cover the bedrock of cape cod in a layer 60 to 180 meters thick. This consists of outwash, which is carried by runoff created by the melting glacier, and till, sediment that has been carried by the glacier (Strahler, Geologist's View of Cape Cod). Basal till, which is a dense mixture of clay, sand, and pebbles with lots of boulders, dragged along the base of the glacier. This type of till is often rich in clay and densely compacted. After the ice melts it deposits sediments that were trapped in ice, called residual till which is softer and more sandy but still has large boulders (Skehan, Roadside Geology of Massachusetts).
The northern part of the horizontal part of the Cape Cod arm is the Sandwich Moraine. It starts 3 miles wide on the west end and tapers to half a mile in the East (Strahler, Geologist's View of Cape Cod). The Sandwich Moraine was formed by the Cape Cod Bay lobe and was thrust up in sheets and shoved into place by the ice. This moraine is characterized by its landscape made up of irregular hills, undrained depressions, boulder-stern ridges, and knob-kettle topography (Skehan, Roadside Geology of Massachusetts). The Buzzards Bay Moraine is the coastal moraine of New England and is made up of thrust-faulted outwash all the way from eastern long island to cape cod, and formed before the sandwich moraine. Part of it makes up the most western part of Cape Cod (Skehan, Roadside Geology of Massachusetts). Most people think that the South Channel lobe did not form a moraine. Meltwater from the lobe deposited gravels and sands into outwash plains but it may not have remained stationary long enough to form a moraine during its retreat (Skehan, Roadside Geology of Massachusetts).
Most of Cape Cod is made up of outwash plains. The outwash plains of the cape began as deltas, which formed that the edge of glacial lakes to the north and south. eastern outwash plains of lower Cape are made of stream deposits over the delta and glacial lake deposits. As meltwater stream flowed west sand and gravel accumulated on the plains, and they continued west, sediment was deposited as deltas in Glacial Lake Cape Cod. Glacial Lake Cape Cod developed as a proglacial lake in the bay when the Cape Cod Bay ice lobe retreat. As the delta grew out into lake outwash plains of the lower Cape expanded in the western direction (Strahler, A Geologist's View of Cape Cod). Because of west flowing streams of meltwater from the South Channel lobe (towards the cape cod bay lobe), the outer cape flows to the west. These streams deposit 3 outwash plains on the outer cape which are younger than most of the inner cape, which slopes south (Skehan, Roadside Geology of Massachusetts). The Mashpee Outwash plain makes up the area south of the Sandwich Moraine. Right by the moraine, the elevation starts at about 80-100 ft, then gradually drops to about 20 ft by the south shore. The outwash plain was formed by meltwater carrying sediment from the glacier, such as fine clay, silt, sand, gravel, and cobbles. The clay and finer sediments were deposited into the ocean, but larger sediments were not carried as far (Skehan, Roadside Geology of Massachusetts).
Changing sea levels have also influenced Cape Cod. As the continental glacier melted, sea level rose about 50 ft per 1,000 years (Skehan, Roadside Geology of Massachusetts). When sea level rose, ragged shorelines were formed. In the period after much of the melting had occurred storm waves were common, and they eroded the coast (Strahler, A Geologist's View of Cape Cod). The sandy glacial deposits that make up the coast were easily eroded and formed into marine scarps.
N., Strahler Arthur. Geologist's View of Cape Cod. Publisher Not Identified, 1988.
​
Oldale, Robert N. “Glacial Cape Cod.” Glacial Cape Cod, Geologic History of Cape Cod by Robert N. Oldale, pubs.usgs.gov/gip/capecod/glacial.html.
​Skehan, James W. Roadside Geology of Massachusetts. Mountain Press Publ., 2006.
​
“Cape Cod National Seashore.” Geology | Cape Cod | Oh, Ranger!, www.ohranger.com/cape-cod/geology.
​
Martin, Margaret."LAURENTIDE GLACIATION OF THE MASSACHUSETTS COAST.” Laurentide Glaciation of the Massachusetts Coast, academic.emporia.edu/aberjame/student/martin1/laurentide.html.
​
“World of Change: Coastline Change.” NASA, NASA, earthobservatory.nasa.gov/world-of-change/CapeCod.
Tectonic Events
The general formation of Massachusetts started with Avalonia, an island arc that is volcanic. (Wexler, williams.edu). About 550 million years ago, movement of tectonic plates caused Avalonia to break off from Gondwana, the first supercontinent, and move towards proto-North America (Wexler, williams.edu). Due to the hot convective mantle in Earth’s core, tectonic plates broke off in massive pieces and caused them to move all over the world. During the Devonian Period, about 400 million, the tectonic plates caused a mountain range to form, an event called the Acadian Orogeny (Wexler, williams.edu). Avalonia was squished between a landmass called Baltica (which would become modern-day Europe) and proto-North America during the Acadian Orogeny (Wexler, williams.edu). When Baltica and proto-North America collided and Avalonia was trapped between, Avalonia land mass accumulated onto proto-North America (Wexler, williams.edu). The compression turned some of Avalonia igneous rocks into metamorphic rocks (Wexler, williams.edu). The igneous rocks changed due to the intense pressure and heat of colliding tectonic plates and landmasses. The bedrock is now made of primarily granite. When Pangea broke up about 200 million years ago, the current location of Cape Cod had a period of erosion, deposition, compaction, and cementation, which covered the metamorphosed rock with sedimentary rocks (Wexler, williams.edu). Without the Avalonian collision and the terrane that resulted after all the tectonic movement called the Avalon terrane, the coast of Cape Cod might be many miles westward (Wexler, williams.edu).
GeoHistories,
sites.williams.edu/geos101/new-england/geologic-history-of-the-north-shore-of-boston-ma/.​
North Beach
Sand
The sand of Sandy Neck Beach was coarse and overall light colored, containing larger pebbles of vastly different compositions. The sand was poorly sorted with lots of different sized rocks interspersed with the fine grains of the majority of the beach. Some parts of the beach has unsorted layers of fine grained sand then layers of almost completely pebbled sized rocks. The farther you dug, the more layers were present.The size of the rocks that were present varied from from about coin to fist sized, with a few rocks begin much larger than fist sized, but those were anomalies. The rocks are rounded by processes of mechanical weathering such as wind and water abrasion. Many of the rocks were granite, but many of the rocks were difficult to identify due to many of their compositions being varied from the rocks in identifications we have done in class. Below are photos of the rocks and sand that made up the beach.
This rock is an igneous rock that is felsic, meaning it is mostly light colored. Since it is felsic, it is made of magma that is rich in silica, which also means that this rock formed from continental crust. An idea for this rocks tectonic formation is that about 550 million years ago, movement of tectonic plates caused Avalonia to break off from Gondwana, the first supercontinent, and move towards proto-North America (Wexler, williams.edu). This rock is also phaneritic, which means it has visible and coarse grains. This also means that it is intrusive, so the rock cooled slowly below ground in a magma body (pluton) which also classifies this rock is plutonic. Some possible rocks and minerals this rock is made up of is rhyolite, quartz and potassium feldspar. Its shape is due to water abrasion, where the water picked up grains of sand and polished the rock, giving it its rounded shape. The rock was also subjected to wind abrasion, which left it pitted but polished in other areas.
This rock is also an igneous rock but it is intermediate, which means it is a 50/50 mix of light and dark minerals. That means that this rock most likely formed at a convergent boundary of oceanic and continental crust. One possible tectonic way this rock ended up like this was from a volcanic eruption at a continental-oceanic convergent boundary. It has an aphanitic texture, meaning that is an extrusive rock and cooled quickly, so there was not enough time for large crystals to form. It was transported to Cape Cod by the Laurentide ice sheet, where it was most likely deposited as till and is a smaller piece of a larger rock that got broken up by weathering. It has some pitting from wind abrasion and is rounded from water abrasion. The discoloration could be from chemical weathering or different compositions of magma. Minerals this rock may be composed of include plagioclase feldspar, pyroxene, biotite, and amphibole.
This rock is igneous and intermediate (50/50 mix of light and dark minerals). It formed at a convergent boundary, most likely between continental (felsic) and oceanic (mafic) crust. This rock has a porphyritic texture. The rock was cooling slowly, underground (intrusive) which allowed it to form some large crystals, but a sudden eruption caused the rest of the rock to cool very quickly, forming much smaller crystals. It was also transported by the Laurentide ice sheet, possibly picked up by plucking, and is a smaller piece of a larger rock. It has been weathered by water abrasion, causing it to become rounded. Some minerals it possibly contains are amphibole, Na feldspar, and K feldspar.
This rock is also igneous. It is granite, which is felsic and aphanitic. It most likely formed at a continental-continental convergent boundary. It formed from magma rich in silica, low temp minerals, mostly light colored. It possibly contains quartz, muscovite mica, and potassium feldspar. It has been rounded by water abrasion, and the darker crystals have been weathered more because they are a higher temperature mineral, which makes them more susceptible to weathering. This rock was also transported by the Laurentide ice sheet.
Beach Face
Berm Crest
Swash Zone
Berm
Foredune
Swash Zone
Dunes
Scarps
Beach Profiles
Beach Profile #1 was taken on the East side of the beach and Beach Profile #2 was taken on the west side of the beach. Each profile had the features of the beach profile labeled on it. No storm occurred before the profiled were taken. Beach Profile #1 is longer than Beach Profile #2. One possible reason for this is that the longshore current is traveling from east to west, depositing sand along the west side, and eroding in the east. It is also possible that the difference in lengths is due to the fact that it is Spring, so the beach has not been build back up by smaller summer waves yet. It is possible that the beach face and berm will get steeper as summer waves come and build the beaches back up, making the switch from the berm to the beach face more drastic. There is no offshore sandbar because the smaller waves have already built up part of the beach face with it since it is spring and not the middle of winter. The dunes that were photographed will also become wider and taller as more sand is added to the beach.
Glacial Effects
This beach was much rockier than the first beach we visited. The glacier reached the north side of the cape, so material here is not outwash, but till. Till is sediment that has been carried by the glacier, and is deposited where the glacier melts. Also, till contains larger sediments than outwash, because it isn't being transported by water, and is instead deposited in place, having only been transported in the ice. Till is alos unsorted because wind or water is not present in its deposition. The fact that all these rocks were transported here from the glacier explains why they are all of the different compositions, as they are not from the bedrock below. The dunes at this beach were also larger and more plentiful than the dunes at the south beach because the meltwater deposits outwash as it goes, so by the time it reached the south end of the arm there was less left, but here at the northern part, the material was deposited directly by the glacier.
South Beach- Craigville Beach
Sand
There were 2 different types of sand at Craigville Beach, one lighter and finer, the other slightly orange and larger grained. The first type of sand, the whiter sand is in the left photo on the left hand. This sand was located closer to the berms. The second type of sand, the larger grained and orange, was located closer to the swash done. There were some pebbles located in the more orange sand, but those were relatively small. The white, fine sand did not have any pebbles in it and was uniformly fine grained. The sand was mainly composed of fine grains with some light shells interspersed . Near the swash zone where only the darker sand was located, there were larger pebbles that had washed up on the beach.
Beach Profiles
Beach Profile #1 was done on the West side of the beach and Beach Profile #2 was done on the East side of the beach. Each profile has the features of the beach labeled on it. No storms occurred before the beach was profiled. It is possible that Beach Profile #2 is longer because the beach is formed on a curve (see photos above) so the longshore current could have deposited more sand along the East side of the beach and eroded more on on the West side of the beach if the current was traveling in that direction. It is also Spring and not Summer, so smaller waves have not built the beaches back up from when they were eroded by larger waves in the winter. The smaller waves could have build up one part of the beach (Beach Profile #2) more than the other part of the beach (Beach Profile #2), causing inconsistency in the lengths of the whole profile, as well as the specific areas of the profile. There is no offshore sandbar since it is spring, the smaller waves had already started to build back up the beach face, but not enough to have the beach appear to be a summer beach. As the smaller waves continue to build the beach back up, the berm to beach face will be a more drastic change, and the beach face will be steeper. The berm will also be longer, and the dunes that were photographed will be taller and wider as sand is added to the beach. It is also possible that both of the beach profiles are shorter than they used to be, because both profiles were taken on the East side of the jetty that was built on the beach. If the longshore current was traveling East to West, it would have deposited (the West side of the jetty) would have been eroded due to the fact that that side of the beach was not receiving longshore current sand deposits.
Beach Features
Beach Face
Swash Zone
Berm Crest
Berm
Swash Zone
Foredune
Glacial Effects
This beach had smaller dunes that the North Beach, as well as significantly fewer rocks and larger sediments on the beach. This is due to the fact that the glacier stopped on the north side of the cape, so all material here is outwash, and was deposited by glacial meltwater, not the glacier itself. Less material has reached this side of the cape because the meltwater deposited material as it flowed south, so less material was available when it reached the furthest south edge of the cape. It also didn' have the velocity to carry larger material this far. Much of the larger material was deposited further north, and the meltwater was only able to carry fine material this far. Sediment here is also sorted because water was involved in its deposition process.
Rocks Found at Craigville Beach
This rock is quartzite, a metamorphic rock that formed from sandstone under intense heat, pressure, and chemical change. One possible way the sandstone metamorphism what when Baltica and proto-North America collided, with Avalonia was trapped between (Wexler, williams.edu). The Avalonia land mass accumulated onto proto-North America (Wexler, williams.edu). The compression turned some of Avalonia igneous rocks into metamorphic rocks (Wexler, williams.edu). Most of the rocks we found on Craigville beach were igneous, so this was an exception to what we looked at. We were able to identify due to the fact that it did not react with hydrochloric acid. It was easy to narrow it down to marble or quartzite due to the non-foliated layers, but since quartzite formed from sandstone, it would not react with hydrochloric acid. The edges of the rock were rounded from water abrasion.
The rock is diorite, an igneous rock that is intermediate, meaning it is a 50/50 mix of light and dark minerals. Intermediate rocks generally form at convergent boundaries with a mix of oceanic and continental crust. Diorite is also intrusive, meaning it cooled slowly below ground. the rock could be intermediate and intrusive form any number of tectonic events in Cape Cod's past during period such as when Avalonia was squished between Baltica and Proto-North America, because there were periods when these plates were not moving, allowing the rocks to cool intrusively (Wexler, williams.edu). The small amount of movement during those periods allowed for the rock to stay igneous and not change to a metamorphic rock due to increased heat and pressure. Diorite has a phaneritic texture, meaning it has visible/coarse grains, which also indicates that diorite is intrusive. Diorite can possibly be made of quartz and muscovite mica, due to some shine in the rock that the camera can not pick up. Additionally, it can be made up of basalt and gabbro, which are dark-colored oceanic rocks, which is plausible due to intermediate rocks forming at oceanic-continental convergent boundaries. The rounded appearance of the rock is from water abrasion.
It was difficult to identify this rock as either andesite porphyry or shale because it essentially weathered beyond the point of recognition.
Andesite porphyry is an igneous rock that has a porphyritic texture, meaning it has large grains mixed with tiny grains from two different stages of cooling. It is also intermediate, so it is a mix of 50/50 dark and light minerals, usually forming at convergent boundaries. It could have formed from any of the many collisions that the Avalon territory went through in the course of its formation. For example, Avalonia collided with Baltica and Proto-North America, as well as many smaller tectonic plates (Wexler, williams.edu). This rock is rounded from lots of water abrasion, with some pitting from wind abrasion. It is very smooth overly since it has had lots of weathering from both mechanical and chemical process, due to it being located on the beach.
This rock is could also possibly be highly weathered shale, which forms when weathering and erosion deposit materials by wind, water, and glaciers. Shale is a prime example of compaction when particles are pressed by overlying weight, so water is squeezed out of the pores. When the water is squeezed from mud and clay and compacted, shale is formed. The rock is poorly sorted, with tiny grains mixed with larger grains, giving it an almost polka-dot appearance with the larger grains standing out. The grain sorting also appeared similar to when igneous rocks have phaneritic textures, which made it difficult to identify. The grains in the rock are all rounded. It is also possible to classify this as metamorphosed shale, which is slate, but we couldn’t do that since we couldn’t break open the rock to see if it is foliated which would mean the rock is slate and was previously shale.
This rock is granite, as felsic rock, which means it was formed from magma rich in silica, indicating the rock formed from continental crust. The felsic composition also means it is composed of low temp minerals such as quartz, muscovite mica, and potassium feldspar and is mostly light colored. Avalonia is composed of continental crust, and this is what Cape Cod is made from, so this granite could have formed from Avalonia or any other piece of continental crust it collided with its long tectonic past (Wexler, williams.edu). Granite is also intrusive, meaning it cooled slowly below ground in magma bodies. For this rock to have been able to form intrusively, it would have had to form at the end of Avalon’s formation when it was not moving anymore and had begun to cool over a long period of time to form the land Cape Cod is now. This rock is also rounded from water abrasion and slightly pitted from wind abrasion that is not visible in the photo.
GeoHistories, sites.williams.edu/geos101/new-england/geologic-history-of-the-north-shore-of-boston-ma/.​
Human Effects and Conservation of Beaches
There was a jetty located on the South Beach (Craigville Beach). As it was too far away from us, it was difficult to photograph. This image was taken off the a vacation website for Craigville Beach. It is possible that the longshore current was traveling East to West and depositing sand on the East side of the jetty, since the beach on the East side of the jetty was wider that the west side. That means that the longshore was depositing on the East side of the jetty and eroding on the West side of the jetty. The only reason the beach has change in this way is due to humans creating the jetty as they built in the area.
R., Brian, et al. “Craigville Beach, Centerville, Cape Cod.” WeNeedaVacation.com, 18 Aug. 2018, www.weneedavacation.com/Beach/Craigville-Beach-Centerville/.
While on Sandy Neck beach, we located a scarp on the beach as saw that it was strangely two different colors. When we got closer we realized that in order to keep sand from eroding off the scarp, builders had installed fiber rolls on the sand. These are installed during winters months to keep part of the beach from eroding too much due to strong storms. These rolls are kept in place with stakes that go deep into the sand to stabilize the steep slope. They can also be used directly in front of beach homes to absorb wave energy and stabilize sand (Fager, npr.org). The ones we saw were not covered, but most fiber rolls are buried into sandy slopes and shrubs and plants are planted on top of them, causing them to look more like natural dunes than rolls (Fager, npr.org). The rolls are filled with sand or coconut fibers (Fager, npr.org) which are the two most popular fillings that are the most effective against erosion. Where the beach starts and the dune begins, there is always more erosion, even with a fiber roll inside the dune. So, the rolls are effective, but not enough to stop erosion on the beaches permanently (Fager, npr.org).
At the bottom of the steeper slopes we encountered, there was newly planted vegetation that was definitely planted by humans, since they were perfectly spaced out. While these plants were young, they will go on the support the loose sand at the base of the dunes, which prevent them from eroding as fast. As the roots of the plants spread out in the sand, they will keep the grains at the foredune from being moved by the wind. Since the dunes are not just piles of any anymore with lots of vegetation growing on them and in them, they will be less eroded when storms and strong winds try to move the sand that makes them up.
One human conservation effort for the animals living on the beaches is to rope off specific areas where the animals lay their eggs in order to keep humans from crushing the eggs. Signs are places with warnings not to walk in those areas due to the eggs that, in this case, birds have laid during their breeding season. The birds on Sandy Neck beach are plovers, and they dig slight depressions to lay their gray spotted eggs (Encyclopedia Britannica, “Plovers”). These eggs are hard to spot due to the rocky terrain of the north beach, so conservation efforts are difficult. The areas blocked off tend to be the calmest area of the beach, allowing the eggs to develop with little disturbance.
Beaches on the Cape are popular areas to build beach homes. But, some problems come from living directly on the beach. We saw houses that were less than 100 feet away from the beach, with paths over the dunes for easy access. The dunes are easily eroded when humans walk over them every day, so some areas are fenced off to preserve the important sources of extra sand for the beaches (bottom right). There were also rip raps located in front of some of the houses, which are boulders parallel to the shore that prevent erosion of beaches in front of beaches. There were also concrete blocks at the end of the parking lot where the beach began that prevented the sand from spilling out onto the parking lots and getting blown away by the strong winds that occur at the beach in winter months. The houses are possibly in danger if they were not built on strong foundations since sand can be easily moved even under the tremendous weight of a house. The movement of sand under the house can cause cracks in the foundation, which can lead to disastrous support issues of the structure
We saw a few people who were adding sand to the beach areas outside their homes, which had been highly eroded due to stronger winter waves and winter storms. This is a tiny form of beach nourishment, which is adding sand to beaches. But this is not permanent because sand is always being eroded from beaches from wind and waves. On a larger scale, beach nourishment adds thousands of cubic feet of sand to eroded beaches. But, this is a costly process, and the sand will be moved by the longshore current or erode by storms anyway. So, the people adding sand to their beaches are not really solving the problem for more than a few months.
Britannica, The Editors of Encyclopaedia. “Plover.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 29 Aug. 2013, www.britannica.com/animal/plover.
​
Fager, Hayley. “As Dunes Disappear, Fiber Rolls Protect Cape Cod Homes From Coastal Erosion.” NPR, NPR, 9 Apr. 2019, www.npr.org/2019/04/09/711097302/as-dunes-disappear-fiber-rolls-protect-cape-cod-homes-from-coastal-erosion.
​
Images:
R., Brian, et al. “Craigville Beach, Centerville, Cape Cod.” WeNeedaVacation.com, 18 Aug. 2018, www.weneedavacation.com/Beach/Craigville-Beach-Centerville/.
Salt Marsh
For this salt marsh we went to the Barntable Great Marsh
Common Reed
Phragmites australis
Habitat: Found on the marsh border and upland edge of the marsh. High marsh species.
Height: Four to fourteen feet tall, usually densely packed.
They are invasive.
(Droiciak, 14)
Smooth Cordgrass
Spartina Alterniflora
Habitat: Tall variation found in low marsh areas and on the edges of creeks. Short variation found in mid marsh and irregularly flooded areas; salt pannes
Height: Less than one to six feet tall
(Droiciak, 20)
Salt Meadow Grass
Spartina Patens
Habitat: Mid marsh areas, as single strands or patches
Height: One to three feet tall
(Droiciak, 18)
Panne/salt panne
Shallow depressions in the mid/high marsh area. Salinity is often high due to lack of drainage and high evaporation. They dry out during dryer seasons, typaclly near the end of summer.
(Droiciak, 5)
How Scientists Use Plants to Determine Sea Level Change
By looking at what plants used to be in an area versus what is there now, scientists can determine sea level change. By looking at a core sample of the soil in a marsh area, scientists can identify certain species that are associated with different levels of the marsh. By observing changes in the vegetation of an area of the marsh over time, scientists can see how the sea level rose and fell. For example, if a plant associated with low marsh areas, such at the Spartina Alterniflora, was growing in an area where the remains of a plant associated with high marsh areas, such as the common reed was found, it could be assumed that sea level had since increased.
The Barnstable Great Marsh had an observatory that allowed guests to view the whole marsh from far away, as well as a pathway that allowed visitors to go directly into the marsh. The soil was essentially mud, so saturated that there was a layer of water located directly above the soil.
Works Cited
Britannica, The Editors of Encyclopaedia. “Plover.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 29 Aug. 2013, www.britannica.com/animal/plover.
​
Drociak, Jen. Life in New Hampshire Salt Marshes: a Quick-Reference Field Guide. N.H. Dept. of Environmental Serivces Coastal Program, 2005.
​
Fager, Hayley. “As Dunes Disappear, Fiber Rolls Protect Cape Cod Homes From Coastal Erosion.” NPR, NPR, 9 Apr. 2019, www.npr.org/2019/04/09/711097302/as-dunes-disappear-fiber-rolls-protect-cape-cod-homes-from-coastal-erosion.
​
GeoHistories,
sites.williams.edu/geos101/new-england/geologic-history-of-the-north-shore-of-boston-ma/.
​
N., Strahler Arthur. Geologist's View of Cape Cod. Publisher Not Identified, 1988.
​
Oldale, Robert N. “Glacial Cape Cod.” Glacial Cape Cod, Geologic History of Cape Cod by Robert N. Oldale, pubs.usgs.gov/gip/capecod/glacial.html.
​
Skehan, James W. Roadside Geology of Massachusetts. Mountain Press Publ., 2006.
​
“Cape Cod National Seashore.” Geology | Cape Cod | Oh, Ranger!, www.ohranger.com/cape-cod/geology.
​
“LAURENTIDE GLACIATION OF THE MASSACHUSETTS COAST.” Laurentide Glaciation of the Massachusetts Coast, academic.emporia.edu/aberjame/student/martin1/laurentide.html.
​
“World of Change: Coastline Change.” NASA, NASA, earthobservatory.nasa.gov/world-of-change/CapeCod.
​
Images:
R., Brian, et al. “Craigville Beach, Centerville, Cape Cod.” WeNeedaVacation.com, 18 Aug. 2018, www.weneedavacation.com/Beach/Craigville-Beach-Centerville/.
​