Contributions and Credits
Guidebook Planning and Preliminary Field Reconnaissance: James W. Head
Cover Design: Peter Neivert
Guidebook Design: James Dickson
Historical Summaries: Nancy Christy
Map Compilation: James Dickson
Outcrop Photographs: Wes Patterson
Guidebook Compilation: Wes Patterson
Field Trip Logistics: Anne Côté
Field Trip Leaders:
Dr. Terry Tullis, Department of Geological Sciences, Brown University
Dr. James Head, Department of Geological Sciences, Brown University
Wes Patterson, Department of Geological Sciences, Brown University
Dr. Geoffrey Collins, Wheaton College, Norton, Mass.
Field Trip Log, Saturday June 21, 2003
8:30 AMLeave Brown and proceed to Gano Street and Interstate 195E.
-Mile 1.5 Enter I-195E.
-Mile 1.9 Right side of road: Outcrops of Rhode Island Formation metasediments.
-Mile 7.0 Enter Rehobeth.
-Mile 8.3 Enter Swansea.
-Mile 8.6 Right side of Road; Cardi's furniture parking lot; Large glacial erratics.
-Mile 8.9 Large outcrops of R. I. Formation.
-Mile 10 Massachussetts State Information Center.
-Mile 11.4 Pass I-195 Exit 3 (Route 6).
-Mile 13.3 Pass I-195 Exit 4 (To Route 103). Brayton Point Power Plant visible on the right.
-Mile 14.5 Approaching Braga Bridge over Fall River and the city of Fall River on the eastern bank. To left of bridge note the battleship USS Massachusetts. During the decades following the Civil War and well into the 20th century, Fall River was a prominent textile-producing center, taking advantage of its harbor location, mild climate, and the waterpower of the Quequechan River. The city in fact takes its name from the Quequechan ("Falling Water" in Wampanoag). Most mill buildings are built of brick, but since Fall River is situated on a ridge of granite, that material was used in constructing the mills here, with the lower walls made three feet thick to withstand the vibrations of the looms. Many of these mills still stand along the river.
-Mile 15.9 Pass I-195 Exit 5 (Route 79-138).
-Mile 16.3 Pass I-195 Exit 6-7 (Route 81).
-Mile 17.3 At I-195 Exit 8A, take exit onto Route 24 South.
-Mile 19.6 Entering Tiverton, Rhode Island. Note change in road conditions.
-Mile 21.6 Pass (Exit 6) Fish Road.
8:55 AM Informal Stop. 10 minutes.
-Mile 22.2 Late Proterozoic Granites of Southeastern Rhode Island. Short stop. This is the Bulgarmarsh Granite and was dated by Walt Galloway, a graduate student at Brown, as part of his Master's thesis. The Rb/Sr whole rock age was 516 (plus or minus 13) million years, Late Cambrian, although the granite is mapped as Zseg (Late Proterozoic) on the RI State Geologic Map. As can be seen on the geologic map, this unit occupies much of the area east of Tiverton. Excellent xenoliths at northern edge of outcrop. These xenoliths may be from the older Newport Group, which we will see later in the morning.
9:05 AM Depart stop and proceed south on Route 24.
-Mile 22.8 Approaching Tiverton: Mount Hope Bay to the right, Mt. Hope Bridge straight ahead, Sakonnet River to the left. Gov. William Bradford obtained an English patent for this area in 1629, purchased the land from the Pocasset tribe, and named the village after Tiverton in England. During the Revolutionary War, Tiverton became an asylum for Americans fleeing from Aquidneck Island, which was occupied by British forces for nearly 3 years.
-Mile 24.9 Exit at Portsmouth/Bristol exit and turn toward Portsmouth.
-Mile 25.1 Turn right onto Route 138 South. Stay on Route 138 South for a while through Portsmouth, "The Birthplace of American Democracy".
-Mile 26.8 Curve in road to right; white Episcopal Church on left.
-Mile 27.7 Portsmouth Town Hall on right. Portsmouth was founded in 1638 by a group of 19 colonists from the Massachusetts Bay Colony. Their leader, Anne Hutchinson was a nonconformist eager to establish a community of her own. She became the first woman to found a town in North America and her Portsmouth Contract was based on English rather than Mosaic law. Portsmouth was home to the first black regiment, which fought in the Battle of Rhode Island in the Revolutionary War. Farming and shipbuilding have been important activities in Portsmouth from the early years to the present.
-Mile 29.8 Sakonnet River and farms on left.
-Mile 31.5 Enter Middletown.
-Mile 32.2 Rhode Island Nurseries.
-Mile 32.9 Turn left onto Route 138A South (Newport Beaches). This is Aquidneck Ave.
-Mile 33.9 Cross Green End Avenue.
-Mile 34.9 Dead end; take a left toward "Newport Bridge, Beaches".
-Mile 35.3 At traffic light (Atlantic Beach Club) take a sharp left, back on to Purgatory Road. Continue down Purgatory Road.
-Mile 35.8 St. George's School on left.
-Mile 36.0 Turn right onto Tuckerman Ave. and take the first immediate left into the parking lot for Purgatory Chasm.
9:30 AM Stop 1: Purgatory Chasm. 45 minutes.
10:15 AM Depart Stop 1. Take right out of parking lot, left at Stop sign onto Purgatory Road, and retrace steps straight to traffic light.
-Mile 37.0 Traffic light at Purgatory Road and Route 138 A (Flo's Clam Shack). Take left turn onto 138A (Memorial Boulevard).
-Mile 37.2 Enter Newport.
-Mile 37.7 Cliff Walk on left.
-Mile 38.3 Take left turn at traffic light onto Bellevue Avenue (Newport Mansions).
-Mile 38.4 Tennis Hall of Fame on left.
-Mile 38.5 Begin mansion row. On right Kingscote (1841), Isaac Bell (1985), Elms (1901).
-Mile 39.3 Chateau-sur-mer on left.
-Mile 39.6 Rosecliff (1902).
-Mile 39.8 Marble House (1892) on left.
-Mile 40.2 Belcourt Castle on right.
-Mile 40.3 Take right at dead end.
-Mile 40.4 Take right turn to begin Ocean Drive and immediate left onto Ocean Drive.
-Mile 41.0 Rocks on right are granites of Southeastern RI.
-Mile 42.0 Goose Neck Cove: Rocks are Newport Group Price Neck Formation.
-Mile 42.7 King's Beach: Rocks are Newport Group, Newport Neck Formation. Lots of outcrops along the shore.
-Mile 43.3 Begin Brenton Point.
-Mile 43.9 Northwest end of Brenton Point Parking Lot, enter and park.
10:40 AM Stop 2: Brenton Point: 40 minutes.
11:20 AM Leave Brenton Point, turn right onto Ocean Ave.
-Mile 44.3 Stone Gate on right.
-Mile 44.5 Turn left into Castle Hill Inn and Resort.
-Mile 44.9 Inn at Castle Hill.
-Mile 45.3 Return to Ocean Drive, and turn left onto Ocean Drive.
-Mile 45.4 Bear left toward Fort Adams.
-Mile 45.6 Pass Oceancliff Mansion on left.
-Mile 46.2 Stop Sign; turn left onto Harrison Avenue. Pass Hammersmith Farm on left; former home of Jackie Kennedy family.
-Mile 46.6 Turn left into Fort Adams.
-Mile 46. 8 Turn right into parking lot.
11:35 AM Lunch Stop and inspection of rocks in Fort Adams vicinity. 60 minutes.
12:35 PM Drive down to Fort Adams and turn around.
-Mile 47.8 Fort Adams. Return to main road.
-Mile 48.6 Turn left onto Harrison Avenue, then proceed straight at stop sign on Halidon Avenue.
-Mile 49.9 Pass Ida Lewis Yacht Club on left.
-Mile 50.1 Statue of French General Rochambeau on left at point where French troops disembarked when they came to help the Americans in the Revolution in 1780. Rochambeau led these troops in the decisive American victory against the British at Yorktown (it was a different "coalition" then).
-Mile 50.4 Turn right onto Thames St and proceed to Narragansett Avenue.
-Mile 50.6 Turn Left onto Narragansett Avenue.
-Mile 50.7 Turn left onto Spring Street. Proceed down Spring Street.
-Mile 51.4 Turn left at traffic light onto Memorial Boulevard. Follow signs to RI 238, Newport Bridge.
-Mile 51.5 Newport Wharf Area.
-Mile 52.2 Dead end at cemetery; Turn left onto Farewell Street.
-Mile 52.7 Turn right onto Route 138 W to Jamestown. Cross Newport Bridge (Toll). Naval War College on right as you cross the bridge; final resting place of Captain Cook's ship Endeavor, is slightly offshore of the Naval War College.
-Mile 54.8 Top of Newport Bridge, Aquidneck Island ahead, town of Jamestown on right.
--Mile 55.8 Toll Booth; pay $2.00 toll. Bear right onto Jamestown exit, right to Jamestown.
-Mile 56.2 Dead end; Turn left onto Canonicus Avenue.
-Mile 57.1 Stop Sigh; turn right onto Narragansett Avenue into Jamestown.
-Mile 57.4 Stop sign, flashing red light; turn left onto Southwest Avenue.
-Mile 58.1 Bear right across spit.
-Mile 58.4 Proceed straight. Entrance to Fort Getty on right.
-Mile 60.4 Beavertail Farm on left. Continue south on Beavertail Road until the end (Beavertail) and the light house.
-Mile 61.2 Beavertail.
1:10 PM Stop 3: Beavertail Point. 60 minutes.
2:10 PM Depart Beavertail Point. Retrace steps north on Beavertail Road, cross spit.
-Mile 64.5 Bear left onto Southwest Avenue and proceed north through town.
-Mile 65.0 Stop sign at Narragansett Avenue. Proceed straight north (street is now North Main Street).
-Mile 66.5 Jamestown Windmill on right.
-Mile 66.7 Watson Farm on left, 1789.
-Mile 67.1 Go under bridge and turn left onto Route 138 W.
-Mile 67.6 Take first right onto Beacon Avenue exit. Proceed down Beacon.
-Mile 68.0 Turn left onto Spirketing Street.
-Mile 68.2 Dead end: Turn left onto Seaside Drive. Proceed to Bridge underpass.
Mile 68.6 Park under Bridge underpass.
2:25 PM Stop 4: Jamestown Bridge. 30 minutes.
2:55 PM Leave Stop 4: Jamestown Bridge. Return north on Seaside to Spirketing, right on Spirketing.
-Mile 69.2 Right onto Beacon.
-Mile 69.6 Turn right onto Route 138W. Cross Jamestown-Verrazano Bridge.
-Mile 70.3 Top of Bridge. Good panorama of western Rhode Island and Plum Point in foreground along shore.
-Mile 71.6 Pass through outcrops of the Rhode Island Formation of the Narragansett Bay Group.
-Mile 73.1 Stook Hill road cut and outcrops. Pull off the side of the road as far as possible.
3:05 PM Stop 5: Stook Hill. 30 minutes.
3:35 PM Leave Stop 5: Stook Hill. Continue to proceed west on Route 138 W.
-Mile 74.0 End of highway, take exit for Route 138 W and then loop around, stay in same lane and immediately exit onto Route 138 E, so that you are retracing your steps on the opposite side of Route 138.
-Mile 76.5 Take exit for Route 1A South to Narragansett and then right onto Route 1A South at the end of the ramp. This is the general area of Saunderstown. The 13.9 square mile area that runs between the eastern bank of the Pettaquamscutt River and the western shore of Narragansett Bay became a popular summer resort, rivaling Newport in the 1800s. Narragansetts casino was destroyed by fire in 1901, leaving only "The Towers", a stone arch with towers spanning the road. Likewise, a long pier jutted out into the bay so that vessels could deliver passengers and cargo, but the pier was torn away by heavy surf. There are still 4 public beaches in Narragansett and the harbor at Galilee is the center of Rhode Islands fishing industry.
-Mile 77.0 Gilbert Stuart Museum on the right.
-Mile 77.8 Casey Farm on right, about 1750.
-Mile 79.4 Proceed straight. On the left, South Ferry Road leads to NOAA and the URI Graduate School of Oceanography.
-Mile 83.6 Narragansett Beach (Beach Road).
-Mile 84.1 Left at second traffic light onto Ocean Road.
-Mile 84.2 Go under towers at Narragansett Pier and continue along Ocean Road.
-Mile 85.4 Left onto Hazard Avenue at Our Lady of Peace sign.
-Mile 85.5 Drive to parking lot at end of block.
4:15 PM Stop 6: Narragansett Pier Granite. 45 minutes.
5:00 PM Leave Stop 6: Narragansett Pier Granite.
-Mile 85.6 Turn left onto Ocean Road. Proceed south on Route 1A.
-Mile 87.3 Scarborough Beach on left.
-Mile 89.0 Intersection of Route 1A and Route 108. Turn immediately left and pull into parking lot of the Bon Vue Inn. Aunt Carrie's on the right.
5:15 PM Beer and dinner at Aunt Carrie's. One hour and 45 minutes.
7:00 PM Depart Aunt Carrie's for return to Providence.
-Mile 89.0 Proceed north on Route 108.
-Mile 93.2 Junction with South Pier Road. Go straight and bear slightly right following the Providence signs onto Route 1 N. Proceed past Wakefield stop.
-Mile 100.3 Pass Intersection with Route 138 E.
-Mile 101.2 Junction with Route 4 N, bear left on Route 4.
-Mile 110.5 Merge with Interstate 95 North, continue north until Route 195 E and the Gano Street exit. Exit Gano, return to Brown.
-Mile 126.2 Arrive Brown.
8:00 PM Arrive Brown.
A Brief History of Rhode Island
Native American Background:
When the European explorers first arrived on the shores of Narragansett Bay, the Algonquins occupied the area, mostly camping and fishing around the bay in the mild weather, and retreating to hunt in the interior forests during the winter. The largest tribes were the Narragansett (pop. ~6000-7000), occupying the west bay area, and Wampanoags, dominating the east bay region. They called the largest bay island "Aquidneck" (or Isle of Peace). The tribes later joined forces against the colonists in King Philips War of 1675. The Wampanoag sachem "King Philip" (Metacomet) was killed, as were thousands of other Native Americans and about 600 colonists.
In 1524, the Italian navigator Giovanni da Verrazzano, in the service of the King of France, sailed west in search of a route to China. Instead, he became the first European to explore and record his discovery of what is now coastal Rhode Island. In his journals, he compares a small island (later named Block Island) off the southern coast to the Island of Rhodes, which would eventually give the state its name.
In 1636, English clergyman Roger Williams fled religious persecution in the Massachusetts Bay Colony. He headed south and founded "Providence" in gratitude for "Gods merciful providence" that the Narragansetts granted him title to the site and to the surrounding area which he called "Providence Plantations". Thinking Aquidnick Island was the Island of Rhodes cited by Verrazzano, Williams called the island Rhode Island. The colony became known as "Rhode Island and Providence Plantations", which is still the official name of the state. Two years after Williams, Anne Hutchinson came seeking religious freedom, founding Portsmouth on the north coast of Aquidneck Island. William Coddington headed further south, founding Newport on the south coast of the island, as another haven for religious freedom.
Newport developed into a sophisticated and prosperous city, with shipping and commerce as the staples of the economy. Shipbuilding was (and is) an important industry, but Newports prominence was due mostly to the lucrative triangle trade: "rum distilled in RI was exchanged for slaves in Africa who were sold to West Indian sugar planters who paid in molasses to make rum". Across from Newport, in the west bay area, the rich soil and climate gave rise to large, prospering farms similar to the plantations of the south.
One hundred years after King Philips War, RI became the first of the 13 colonies to renounce allegiance to Great Britain and the last of the 13 colonies to ratify the constitution in 1790.
Postwar Prosperity and the Nineteenth Century:
In 1790, English immigrant Samuel Slater circumvented the English embargo on machinery by constructing from memory several Arkwright spinning machines. He installed them at Pawtucket, harnessing the waterpower of the Seekonk River. Over the next 30 years, the textile industry took root in Rhode Island. Villages grew up around the mills as immigrants from Canada and Ireland began to join the labor force. Tool making and jewelry became established as the industrial revolution took root, overshadowing commerce and agriculture.
Overview of Rhode Island Geological History
All outcrops visited on this trip were once part of the Avalon microcontinent. The formation of the Narragansett Basin of Rhode Island and Massachusetts and the polyphase deformation geometry of the Pennsylvanian-age basin sediments can be explained by collision and strike-slip interactions between the Avalonian microcontinent, Laurentia, and Africa. Avalon existed in the Devonian as an amalgamation of what is now coastal New England, southern New Brunswick, much of Nova Scotia, the Avalon Peninsula of eastern Newfoundland, southeastern Ireland, Wales, England and parts of Belgium and northern France. It was located between Laurentia (present day North America, Greenland, Great Britain and some of eastern Russia) and Africa before the closing of the Iaepitus ocean to form Pangea. The rocks of the Avalon subcontinent can be further subdivided into the Hope Valley and Esmond-Dedham Subterranes (Figure 1. See also the stratigraphic column in this guide). The western Hope Valley Subterrane is composed of highly deformed late Precambrian leucocratic granite gneisses and the eastern Esmond-Dedham Subterrane is composed of variably deformed 600-650 Ma granitic rocks intruded by Ordovician to Devonian anorogenic plutons. The contact between these two terranes is an Alleghanian suture known as the Hope Valley Shear Zone (O'Hara and Gromet, 1985).
The Acadian Orogeny, occurring during the late Devonian, resulted in the accretion of the Avalonian microcontinent with Laurentia (Proto-North America) on the eastern edge of present day New England. The formation of the Pennsylvanian-aged Narragansett Basin reflects post-Acadian tectonic activity; the basin shape, stratigraphy, and sedimentary relationships can be explained by the coalescence of two composite grabens that formed at different times under a strike-slip regime. This was followed during the late Pennsylvanian and Permian periods by the Alleghanian Orogeny which involved the collision between the newly accreted Avalonian terrane and Africa, closing the Iaepitus Ocean. The Alleghenian Orogeny, the major mountain-building event in the central and southern Appalachians, played a major role in the evolution of the northern Appalachians as well. Over the last 20 years, detailed investigations have shown that most of the metamorphism and deformation of rocks east of the Connecticut River in Connecticut occurred during the Alleghanian, rather than the Acadian Orogeny, as previously thought. Pennsylvanian-age rocks comprising the Narragansett Basin of Rhode Island and Massachusetts (Figure 1) provide unequivocal evidence of late Pennsylvanian to Permian deep-seated, high-grade collisional deformation (Mosher, 1983; Murray, 1988; Snoke and Mosher, 1989 and references therein). Within the 15 million years following deposition, Pennsylvanian sediments were multiply deformed by large-scale, recumbent nappe-like folds concurrent with upper amphibolite facies metamorphism and were intruded by a peraluminous, S-type granite (Zartman and Hermes, 1987; Reck and Mosher, 1989; Mahler Cogswell and Mosher, 1994). Synintrusion sinistral and subsequent dextral shear zones deformed the well-foliated metasedimentary rocks, recording complex transcurrent motion late in the orogeny (Reck and Mosher, 1989; Mosher and Berryhill, 1991; Mahler Cogswell and Mosher, 1994; Burks and Mosher, 1996).
This trip traverses the southern Narragansett Basin, stopping at several localities in the Esmond-Dedham terrane that express different aspects of the Alleghanian orogeny. It examines the early polyphase deformation as it is expressed at different structural levels and the superposed structures in well foliated pelitic rocks that record the kinematic history of the subsequent ductile transcurrent shear zones. The trip also examines the effects of metamorphism and its relationship to deformation, intrusive relationships with the Narragansett Pier Granite, depositional environments within the Narragansett Basin, and tectonized erosional contacts between the basal Pennsylvanian and underlying crystalline basement.
(sources: Burks, Mosher, and Murray ; Reed, W. and Monroe, J.S. Historical Geology, 1993; Mosher, 1983)
Glacial Geology of Southeastern New England
Cape Cod, Martha's Vineyard, and Nantucket are a result of the large continental glacier (ice sheet) that reached its maximum extent at Cape Cod about 21,000 years ago. As it advanced, the ice sheet transported an embedded load of rock and sand (glacial till) that had been eroded from the land surface. This sediment load was carried to the glacier's edge and deposited to form moraines or carried away from the glacier by streams of meltwater and deposited in an outwash plain. The spine of Cape Cod is formed by two moraines that join at the Cape Cod Canal
The sea cliff is a landform that is common along Cape Cod and at Block Island. These cliffs can be as high as 30 to 40. Erosion by waves carries material away from the cliff base and creates the steep face that rises above the ocean. Beaches are built from the eroded material by deposition at the base of the cliffs or by deposition in a long, narrow sand bodies that are parallel to the coast. These features are called barrier islands or spits, if connected to the mainland. They are maintained and shaped by currents moving parallel to the shoreline (longshore currents). The area behind a barrier beach or spit is protected from open ocean waves and is a low-energy marine environment that can support marine wetlands (salt marshes). Dunes are shaped by winds and provide an important barrier between the open ocean waves and the back barrier wetlands. However, the dunes are dynamic features that are subject to change on rather short time scales, especially if not stabilized by the presence of dune grasses.
Outwash plains are the most common glacial landform on the Cape and Islands. Two large outwash plains occur on Nantucket. A single outwash plain makes up much of Marthas Vineyard. Upper Cape Cod is, in part, made up of three outwash plains and the lower Cape consists mostly of three outwash plains.
Outwash plains are broad, flat, alluvial surfaces, formed by braided meltwater streams, that slope gently away from the position of the former glacier. They are underlain by stratified drift, mostly gravelly sand. The meltwater sediments in the upstream ends of many outwash plains were deposited against and over the front of the glacier. When the glacier melted back, the deposits and the outwash plain surface collapsed to form what is known as an ice-contact head, a surface of irregular topography that, in most places, slopes steeply toward the former position of the ice margin. Thus, the ice-contact slopes mark former positions of the ice margin in much the way that end moraines do.
Deposits beneath the ice-contact slope reflect the close proximity of the glacier and are highly variable in composition. They include stratified glacial drift that ranges from coarse sand and gravel to silt and clay. Locally they include till deposited directly from the ice or as flowtills. Small to very large boulders are common within the ice-contact deposits and are scattered about on the ice-contact slope. Some meltwater streams emerged from the ice and passed through end moraines before they dumped their sediment load to construct a broad outwash plain. These outwash plains lack a well-defined ice-contact head.
The surface of the outwash plains are, in many places interrupted by closed depressions (kettles) that mark the sites of ice blocks buried by the outwash deposits. Some outwash plains include many kettles and are termed pitted (like the Mashpee pitted plain). The ice blocks may have been completely buried and contributed little material to the outwash. Others were only partly buried, and, as they melted, they contributed boulders and minor amounts of sediment to the outwash plain deposits. The eastern outwash plain on Nantucket and the Marthas Vineyard outwash plain formed beyond the maximum advance of the Laurentide ice and therefore lack large kettles.
All of the outwash plains on the Cape and Islands are incomplete. They have had their downstream ends eroded away by the sea and many others have had their upstream ends and ice-contact heads partly or completely removed in a similar manner. Some had their upstream ends destroyed by readvances of the glacier during the formation of an end moraine.