A1 The Historic New-Gate and Cobalt Mines of Connecticut
Trip Leader: Norman H. Gray

A2 Archaeological Lithic Sources in Southeastern New England and the Pequot Museum
Trip Leaders: Don Hermes, Duncan Ritchie, Joseph Waller, and Kevin McBride

A3 (see also B2) The New Quaternary Geologic Map of Connecticut and Long Island Sound Basin: Illustrated by two days of field trips along the Coastline and in the Connecticut Valley.
The first-day trip will focus on Long Island Sound geology
Trip Leaders: Janet R. Stone, Ralph S. Lewis, Mary DiGiacomo-Cohen, and Byron D. Stone

A4 Jurassic Cyclostratigraphy and Paleontology of the Hartford Basin
Trip Leaders: Paul E. Olsen, Jessica H. Whiteside, and Philip Huber (Cosponsored by the Eastern Section of SEPM)

A5 Deep-Crustal Barrovian Metamorphism of South-Central Connecticut - This trip is FULL
Trip Leader: Jay Ague

B1 Archaeology of Mineral and Waterpower Resources in Northwest Connecticut
Trip Leaders: Robert Gordon and Mike Raber

B2 (see also A3) The New Quaternary Geological Map of Connecticut and Long Island Sound Basin: Illustrated by two days of field trips along the Coastline and in the Connecticut Valley.
The second-day trip will be in the Connecticut Valley
Trip Leaders: Janet R. Stone, Mary DiGiacomo-Cohen, Jack Ridge, Jake Benner, Ralph S. Lewis, and Byron D. Stone (Cosponsored by the Eastern Section of the SEPM)

B3 Reading the Rock and Landscape Record of the New Haven Region (this trip is recommended for NAGT members)
Trip Leaders: Leo Hickey and Copeland MacClintock

B4 Hartford Basin Cross Section - Southington to Portland, Connecticut
Trip Leaders: Phil Resor and Jelle de Boer (Cosponsored by the Eastern Section of the SEPM)

B5 Bedrock Geology of the New Milford Quadrangle, Connecticut
Trip Leader: Gregory J. Walsh

B6 Giant Staurolite Porphyroblasts in the Bolton Syncline: Tectonometamorphic Implications
Trip Leaders: Mark D. Busa and Norman H. Gray

C1 Sediment Dynamics of the Branford River Estuary
Trip Leader: Gaboury Benoit (Cosponsored by the Eastern Section of the SEPM)

C2 A Visit to the North Branford Trap-Rock Quarry Operated by Tilcon Connecticut Inc.
Trip Leaders: Anthony R. Philpotts, Brian J. Skinner, and Frank Lane

C3 A New Look at the Structure, Stratigraphy, and Basalts of the Pomperaug Basin
Trip Leaders: William Burton, Philip Huber, Gregory McHone, and Peter LeTourneau

C4 Western End of the Honey Hill Fault along the Eastern Bank of the Connecticut River
Trip Leaders: Phil Resor and Jelle de Boer

C5 Discovery of the Lost Alleghanian Magmatic Arc in the Killingworth Dome
Trip Leader: Robert P. Wintsch

Friday trips, September 30, 2005

A1 The Historic New-Gate and Cobalt Mines of Connecticut
Trip Leader: Norman H. Gray

During the 1700 and 1800s Connecticut was the scene of several small entrepreneurial mining ventures. Most of these attempts were short-lived and it is difficult today from the limited tailing piles and collapsed or flooded workings to understand what these early miners were after. The underground workings of two of the more important deposits are still accessible and the nature of the mineralization that attracted the miner’s interest can be seen in place.

The New-Gate mines of Simsbury are hosted by grey colored sandstones in the Hartford Basin Mesozoic redbeds. The main ore (grading up to 13% Cu) was a massive chalcocite replacement of the ankerite cemented zones. The mineralization at New-Gate was discovered in the early 1700s, and worked at intervals up to 1900. For a brief period in the late 1700s the underground workings served as Connecticut’s State Prison!

The Cobalt mines of East Hampton were first prospected in the 1790s, opened as a cobalt source in the early 1800s and then for nickel in the 1860s. Mineralization occurs in Ordovician metasediments just below the Silurian Clough Quartzite. Local legend has it that the first Governor of Connecticut found gold in the area in the mid 1600s. Later miners make no mention of gold even though stringers of native gold are visible in aresenopyrite veins close to their main workings in the Clough. The early miners, who obviously were very resourceful, traced a single folded thin seam of Fe-Co-Ni arsenide bearing garnet amphibolite along strike for over 1200 ft.

This afternoon trip will assemble in the parking lot at the Old New-Gate Prison at 1 pm, explore the underground workings of the mine and then proceed to Cobalt where we should be able to examine several shafts and adits which cut the arsenide seam.  If it is a sunny day we will also challenge participants to find a grain or two of visible gold.

Bring flashlights, waterproof boots and a good hand lens.

Departure time and location: Assemble in the parking lot at the Old New-Gate Prison at 1:00 pm.

Contact: Norman Gray; Email: nhgray@charter.net

Limit on participants: None

Fine-grained felsitic volcanic rocks and soapstone were quarried in southeastern New England by prehistoric Native Americans for the production of stone tools and implements. The major volcanic complexes include the diverse Lynn/Mattapan suite located NE and SW of Boston, and the Wamsutta volcanics near the western boundary of the Narragansett basin in Attleboro, MA. Soapstone sources occur in RI, MA, and CT.  Petrographic and geochemical characteristics of rocks from the source areas have been useful in constraining the source of artifacts from archaeological sites in Massachusetts and Rhode Island.

This trip will visit several outcrops where felsite and soapstone were quarried during the prehistoric period. Discussion will include the geological setting and context of the quarries, the petrographic and geochemical characteristics, and constraints on the distribution patterns of the artifacts.  We also will emphasize the value of these source areas as cultural resources.

The last stop will be at the Pequot Museum in Stonington, CT for a guided tour of some museum highlights and the fort.  Travel time to New Haven from the museum is no more than one hour.

Departure time and location: Departure Time = 8:30AM. Trip will depart from Park and Ride lot on Rt. 138 in Milton, MA.  From I-95N, bear right at Exit 1 (east) onto Rt. 93N (Rt. 128S). Take exit for Rt. 138N, through traffic light at first intersection, past Howard Johnson’s to Park and Ride lot on left side of road (about 0.3 miles).

Contact: Don Hermes, Dept. of Geosciences, University of Rhode Island, Kingston, RI 20881; Phone 401-874-2192; Fax 401-874-2190; Email: dhermes@uri.edu

Limit on participants: None

The first-day trip will focus on Long Island Sound (LIS) geology illustrated by stops along the coast where on-land units become submerged beneath modern sea level and have been mapped beneath the Sound using high-resolution seismic-reflection lines. Beginning at the Marine Sciences building on the University of CT campus at Avery Point in Groton where, on a clear day, we can see four recessional moraines laid down during the retreat of the last ice sheet and the topset plain of one of the earliest ice-marginal deltas built into Glacial Lake Connecticut, which occupied the Long Island Sound Basin as the ice retreated northward from the Charlestown-Fishers Island-Harbor Hill (CFH) Moraine. Exposures are rare and fleeting in this part of southern New England, so fieldtrip stops along the Connecticut shoreline will mostly illustrate the morphology of recessional moraines and ice-marginal deltas as they extend offshore and locally are aligned with subaqueous lacustrine fans deposited at the grounding line of the ice-margin as it retreated sequentially northward in glacial Lake Connecticut. Seismic records and cores from LIS will illustrate the character and distribution of extensive varved lake clay that overlies morainal and lacustrine fan deposits and interfingers with glaciodeltaic deposits along the Connecticut coastline. The postglacial record in LIS includes 1) a through-going channel system carved into the drained lakebed by water entering LIS from the west joined by tributary streams from mainland CT and LI, and exiting the Sound through the lake spillway notch cut into the CFH moraine at The Race; 2) a marine unconformity cut as the early postglacial sea transgressed into LIS rising to as high as -10 m; and 3) a 750 km2 marine delta built from the ancestral Connecticut River into a -40 m relative sea level stand when sea level fell as glacio-isostatic rebound began.  We will discuss these features at stops along the coast including Griswold Point in Old Lyme, Cornfield Point in Old Saybrook, Meigs Point at Hammonassett State Park in Madison, East Rock in New Haven, and Lordship Point in Stratford.

Departure time and location: Meet at 8:00 am at the University of Connecticut, Avery Point Campus, in Groton, CT, Marine Sciences and Technology Building (Parking lot D, adjacent to the Pine Island Harbor and Food Services Building, labeled "Project Oceanology" on campus map). Directions to UCONN, Avery Point campus.

Contact: Janet R. Stone, U.S. Geological Survey, UCONN-Avery Point, 1080 Shennecossett Road, Groton, CT 06340; Phone: 860-405-9210; Fax: 860-405-9214; Email: jrstone@usgs.gov

Limit on participants: None

One of the most obvious features of the Jurassic age strata of the Hartford basin is the characteristic lithological lacustrine cyclicity. What is not widely known, however, is that this cyclicity is pervasive not only in the strata interbedded with the basalt flow sequences, but is also present in the lower 2 km of the overlying Portland Formation. The cyclicity is of Milankovitch origin, reflecting not only the familiar 20 ky climatic precession cycle, but also the 100, 400, and longer eccentricity cycles, as well as the chaotic behavior of the Solar System. We will look at examples of this cyclicity through all of the major Jurassic intervals and will show how that cyclicity is reflected in the preservation and development of the biota in the aftermath of the Triassic-Jurassic mass extinction and the great CAMP flood basalt eruptions.

Departure time and location: Trip will begin at 8:00 AM at CT Dot Park and Ride lots on CT Route 68 (Barnes Rd.) off exit 15 on Interstate Route 91, Wallingford, CT (go here for a map of the Park and Ride location (click on the first Wallingford link, I-91 @ Route 68, exit 15).

Contact: Paul Olsen, Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964-1000; Email: polsen@ldeo.columbia.edu

Limit on participants: None

A5 Deep-Crustal Barrovian Metamorphism of South-Central Connectiuct
Trip Leader: Jay Ague

This trip will examine Barrovian-style metamorphism of sedimentary rocks in south-central Connecticut, and will include classical field areas in the Orange-Milford Belt and the Straits Schist. These rocks were metamorphosed at depths ranging from ~25 to ~35 km and, thus, form some of the deep roots of the Acadian orogen in New England. The field areas contain excellent examples of the characteristic metamorphic minerals that form in metapelitic, metacarbonate, and metabasic rocks from the greenschist through the amphibolite facies. The outcrops will provide ample opportunities for discussion of current problems in petrology and tectonics, including the nucleation and growth of metamorphic mineral porphyroblasts such as garnet; the deformational processes that operate in the deep crust; and the role of fluids in driving metamorphic reactions, triggering deformation, and transporting heat and mass through mountain belts.

Please note that many of the field trip stops will be on Regional Water Authority property; the photographing of dams and other water supply structures is strictly forbidden.

Departure time and location: Trip begins at 9:00 AM at the Lime Kiln on Rt. 69 (Stop 1 of field trip). To get to the Kiln, take Rt. 15 to exit 59, then head north about 2.7 miles on Rt. 69 to intersection with Dillon Rd. Note that because the trip is on a Friday, traffic will be heavy, particularly on Rts. 15, 34, and 69. Excercise extreme caution when driving and crossing roads.

Contact: Jay J. Ague, Department of Geology and Geophysics, Yale University, P.O. Box 208109 New Haven CT 06520-8109; Phone: 203-432-3171; Email: jay.ague@yale.edu

Limit on participants: 40 This trip is FULL

B1 Mineral and Waterpower Resources of the Salisbury District, Connecticut
Trip Leaders: Robert Gordon and Mike Raber

On this trip from East Canaan to Kent Furnace via Falls Village we explore mining and smelting sites, hydropower installations, and evidence of the transformation of land use over the past 300 years.  The people of the Salisbury district in northwest Connecticut exploited the region’s iron ore and waterpower resources with fuel from sustained-yield forestry to build a nationally-important iron industry. They supplied the Continental Army with cannon and were sole-source supplier of iron to the national armories at Springfield and Harpers Ferry. They made locomotive tires and car wheels for railroads as far west as the Union Pacific. Later they were among the first in the east to use high-voltage transmission to export hydroelectric power to distant cities. While mining, smelting, and forest harvesting dominated the region in the mid-19th century residents began a gradual transition from dependence on extractive industry to residential and recreational uses of their land. Woodland tracts assembled for ironworks became today’s forest preserves; the furnaces and forges are today’s historical and archeological sites.

Departure time and location: The trip begins at 0900 at the Beckley Furnace State Industrial Monument on Lower Road in East Canaan, Connecticut. The site is 0.5 miles from the intersection of Lower Road with Route 44; the East Canaan church is a landmark near the intersection.

Entrance to the hydropower station at Falls Village (Stop 3) is restricted to those who have signed up before we reach the power plant. The power company will require a photo ID for admission.

Contact:  Robert Gordon, Department of Geology and Geophysics, Yale University, New Haven, Connecticut; Phone: 203.432.3125; Email: robert.gordon@yale.edu

Limit on Participants: None

B2 (see also A3) The New Quaternary Geological Map of Connecticut and Long Island Sound Basin: Illustrated by two days of field trips along the coastline and in the Connecticut Valley
The second-day trip will be in the Connecticut Valley
Trip Leaders: Janet R. Stone, Mary DiGiacomo-Cohen, Jack Ridge, Jake Benner, Ralph S. Lewis, and Byron D. Stone (Cosponsored by the Eastern Section of the SEPM)

The second-day trip will be in the Connecticut Valley and stops will illustrate some of the depositional systems used to categorize glacial meltwater deposits on the new Quaternary Map, and will also focus on the later history and drainage of Glacial Lake Hitchcock in the Hartford basin. We will visit the Kelsey-Ferguson clay pit in South Windsor, where Jack Ridge has recently obtained paleomagnetic samples and a series of overlapping cores from the upper ~550 varves at the site and successfully matched the section to the newly calibrated New England varve chronology of Antevs, 1922; 1928. A slightly higher 14C-dated lacustrine section across the CT River in Windsor (Matianuck Ave. site, locality 10 on the Quaternary map) will be discussed (and perhaps visited) in light of age constraints that the 13.5 14C ka (16.2 cal ka) date impose on the varve chronology and the varve section at the K-F clay pit. Jack has recently also discovered trace fossils on bedding planes in the K-F clay pit that indicate the presence of fish (freshwater sculpin) in Glacial Lake Hitchcock. The trip will include stops along the Connecticut River in Glastonbury and Rocky Hill to examine the 50-ft terrace cut when the Rocky Hill Dam was breeched and the southern part of Lake Hitchcock drained. We will examine post-lake features including extensive terraces cut into the drained lakebed by waters spilling from the remnant glacial Lake Hitchcock north of the Holyoke Range in Massachusetts. These waters carried sediment down the Connecticut River to build the extensive -40 m marine delta in Long Island Sound. Other post-lake features to be examined include sand dunes, and those enigmatic circular to subcircular, rimmed-depressions that have been interpreted as potential pingo scars indicative of permafrost conditions at the time of Lake Hitchcock drainage; an alternative possibility will be discussed - that these features are water-escape structures associated with the relatively rapid lake drainage, potentially aided by the occurrence of earthquakes generated by the initiation of glacio-isostatic rebound.

Departure time and location: Meet at 8:00 am at the Baldwin Bridge State Boat Launch, Old Saybrook, CT. From the New Haven area take I-95 N toward New London, take exit 67 for CT-154 S (Old Saybrook), bear right at Middlesex Tpke. (CT-154). Turn left at US-1 North (Boston Post Road), bear right, road becomes Ferry Rd. Turn right into Baldwin Bridge State Boat Launch (located under west end of I-95 bridge). A map to the boat launch can be found here.

Contact: Janet R. Stone, U.S. Geological Survey, UCONN-Avery Point, 1080 Shennecossett Road, Groton, CT 06340; Phone: 860-405-9210; Fax: 860-405-9214; Email: jrstone@usgs.gov

Limit on participants: None

This trip will trace some of the geological events that have produced the fabric of the Hartford Basin in the vicinity of New Haven, Connecticut, as well as accounting for the distribution of its resources, vegetation, and population centers. The route of the trip will start on the southeastern margin of the basin and proceed generally northwestward through the New Haven and Meriden areas to terminate on its western boundary. On the way we will examine crystalline rocks of the Avalonian Terrain in the Eastern Highlands, cross the eastern bounding fault, and view the remnant of the deep glacial gorge forming the New Haven estuary. The effect of vegetation and of urbanization on present-day stream flow and sedimentation will be seen near the confluence of Wharton Brook and the Quinnipiac River, and this will be contrasted with styles of sedimentation in the Late Triassic New Haven Arkose. At Meriden we will examine a spectacular pillow basalt in the Early Triassic Talcott flow and associated soft-sediment deformation in the underlying strata. Our route will terminate on metamorphosed sediments of the Iaptus Ocean on the western margin of the basin.

Departure time and location: 8:15 am. Meet the bus at the front entrance to the Klein Geology Laboratory on the Yale University campus (see map). You must reserve space on this trip in advance.

Contact: Copeland MacClintock, Peabody Museum, Yale University, PO Box 208109, New Haven, CT 06520-8109; Email: copeland.macclintock@yale.edu

Limit on participants: 44

B4 Hartford Basin Cross Section - Southington to Portland CT
Trip Leaders: Phil Resor and Jelle de Boer (Cosponsored by the Eastern Section of the SEPM)

This trip traces a classic cross-section across the late Triassic-early Jurassic Hartford (rift) basin. We will work our way up section from the basal non-conformity through the extensive basaltic lava flows, ending at the fanglomerates of the Jurassic Portland formation and nearby eastern border fault. Along the way we will explore important controls on basin formation such as regional tectonic phases, fault segmentation, intra-basinal faulting, and climate forcing.  We will also discuss ongoing controversies such as magma sources and timing and magnitude of slip phases along the Eastern Border Fault.

Departure time and location: 8:00 AM. Start at the Wesleyan parking lot on the west side of Vine St, immediately south of the tennis courts. Head north on Vine St.

Details:
First stop: Southington unconformity. Here lower beds of the New Haven arkose (late Triassic) are overlying a steeply inclined sequence of Ordovician gneisses intruded by pegmatites (355 my) and quartz veins.

Second stop: Hanging Hills of Meriden with exposures of the Holyoke basalt flow (early Jurassic) and views of the Rift Valley.

Third stop: Exposure of the East Berlin formation in three dimensions and lower contact of Hampden basalt flow.

Fourth stop: Outcrop of playa, lake, and landslide (?) deposits of the Portland formation (early Jurassic) in close proximity to the Eastern Border Fault.  Discussion of new ideas concerning the timing of dip-slip motion along this major structure.

Contact:  Phillip G. Resor, Department of Earth and Environmental Sciences, Wesleyan University, Middletown, CT 06459; Phone: 860 - 685-3139; Fax: 860 - 685-3651; Email: presor@wesleyan.edu

Limit on participants: 30

This trip will focus on the results of recently published mapping and geochronology studies in the New Milford quadrangle (Walsh, 2003; Walsh and others, 2004). The trip will visit significant outcrops of Mesoproterozoic basement rocks and their lower Paleozoic cover rocks east and west of Cameron's Line. Visits to Mesoproterozic bedrock exposures will include the oldest dated rock in Connecticut, a 1311 ± 7 Ma granite gneiss, and several exposures of syn-tectonic migmatite and granite providing c. 1.05 Ga Ottawan ages.  Exposures of the Neoproterozic to lower Paleozoic cover rocks will highlight the autochthon, para-autochthon, and allochthon. Stops will also include visits to Ordovician plutonic rocks on both sides of Cameron's Line.

Walsh, G.J., 2003, Bedrock geologic map of the New Milford quadrangle, Litchfield and Fairfield Counties Connecticut: U.S. Geological Survey Open-File Report 03-487, 49 p., scale 1:24,000, http://pubs.usgs.gov/of/2003/of03-487/.

Walsh, G.J., Aleinikoff, J.N., and Fanning, C.M., 2004, U-Pb geochronology and evolution of Mesoproterozoic basement rocks, western Connecticut, in Tollo, R.P., Corriveau, L., McLelland, J.M., and Bartholomew, M.J., editors, Proterozoic Tectonic Evolution of the Grenville Orogen in North America: Boulder, Colorado, Geological Society of America Memoir No.197, p. 729-753.

Departure time and location: The trip will start at the parking lot of the "Big Y" supermarket at the junction of U.S. Routes 202 and 7 in New Milford, CT. The start time is 8:30 AM on Saturday, October 1st, 2005. Please bring a lunch with you. Hardhats are required for Stop 6 at the ASI quarry in the Stockbridge Formation, so please bring your hardhat. Most stops will be close to the road, but there is limited parking at a number of stops, so please try to consolidate vehicles. After Stop 14, we will pass by the "Big Y" if anyone wants to pick up their vehicles for the last two stops.

Contact: Gregory J. Walsh, U.S. Geological Survey, Montpelier, VT 05601; Phone: 802 - 828-4528; Fax: 802 - 828-4465; Email: gwalsh@usgs.gov

Limit on participants: None

This field trip will include visits to some spectacular outcrops in the Bolton syncline, the home of giant staurolite porphyroblasts. The various external forms of staurolite we will observe at the outcrop, such as fan-shaped and flattened lozenge-shaped staurolite, provide clues to an important period of deformation during staurolite growth. Central to these observations is the controversial question - do porphyroblasts rotate? Indeed, Bell and others have traveled from Australia to collect samples at some of the very locations which will be visited in this field trip. Their FIA technique was used to stake their claim that the staurolite and garnet porphyroblasts did not rotate. We have demonstrated that the orientations, external forms, and inclusion trails in staurolite document local shear-induced rotation of up to 150 degrees relative to the external foliation! These contrasting interpretations lead to very different tectonometamorphic histories of the rock during the growth of staurolite. The staurolite porphyroblasts define a preferred orientation in the Littleton Formation which varies with location in the syncline. The orientations and inclusion trails in staurolite at Marlborough, Connecticut will be used to compare with Rosenfeld & Eaton’s tectonometamorphic interpretation at this location, as reported in the 1985 NEIGC field trip. The north-south stauroite lineation observed at locations on the west limb of the syncline formed from post- (or syn-?) staurolite flattening and stretching of the adjacent, lineated Glastonbury Gneiss.

Departure time and location: Meet at 9:00 am at the Park and Ride parking lot in Bolton Notch, CT - west of the junction of interstate I-384 and State Routes 44 and 6 (east of miniature golf and driving range on Route 6)

Contact: Mark Busa; Email: MBusa@mxcc.commnet.edu

Limit on participants: 20-25

C1 Sediment Dynamics of the Branford River Estuary
Trip Leader: Gaboury Benoit (Cosponsored by the Eastern Section of SEPM)

This field trip will show how short-lived radionuclides (especially 7Be) can be used to investigate sediment supply, deposition, resuspension, and net accumulation or export in Connecticut estuaries on time scales from days to years. Sediment deposition/resuspension and its temporal variability in estuaries have important ramifications for navigation/dredging, habitat conditions, nutrient cycles, and transport/fate of toxic substances (e.g., metals, hydrophobic organic compounds).

Estuaries are influenced both by inputs from their watersheds and by material delivered via tidal exchange, though the relative contribution of each varies considerably. The interplay of watershed and tidal influences is complex. Both have regular components (stream baseflow and semidiurnal tides) as well as irregular pulses related to storm events.  Over shorter time scales (days to months), sediments from these two sources may undergo a series of deposition and resuspension events, though the net effect over periods of several years is net accumulation. Estuaries provide unique habitat, but are also repositories for a disproportionate amount of contaminants, which tend to associate with fine-grained, organic-rich sediments.

The trip will visit sites along the Branford River estuary and its watershed and examine interactions among hydrologic (rain, river, estuary, Long Island Sound), sediment (erosion, transport, sedimentation, resuspension, burial, export), and element (radionuclide chronometer/tracers, contaminants) cycles. Two overarching themes will be constructing a mass balance of 7Be in the estuarine-watershed system, and quantifying temporal and spatial patterns of sediment accumulation from hours to years and meters to tens of kilometers.

The trip will begin and end at the Yale Dept. of Geology and Geophysics Kline Geology Laboratory. If time and numbers permit, a sample collected in the field will be returned to the lab for immediate analysis. The Branford River is about a 15-minute drive from the lab.

Departure time and location: Departure Time = 8:30AM. Trip will depart from Kline Geology Laboratory, 210 Whitney Avenue, New Haven.

Contact: Gaboury Benoit, Yale Environment School, 21 Sachem Street, New Haven CT  06511; Phone: 203-432-5139; Fax: 203-432-5023; Email: gaboury.benoit@yale.edu

Limit of Participants: None. The final stop, in the counting lab at KGL, will accommodate fewer than 20 participants, but is optional.

The North Branford quarry, operated by Tilcon Connecticut Corporation, boasts one of the longest trap-rock quarry faces in the world, exposing the lower and central parts of the 200-meter-thick Mesozoic Holyoke flood-basalt flow in over 8 km of working face. The quarry is adjacent to Lake Gaillard, one of the region's major reservoirs. Water from the reservoir passes beneath the quarry through the Great Hill Tunnel and is delivered to a filtration plant for distribution into the New Haven area. The excursion will look at the operation areas of a trap-rock quarry and explanations will be given of the flow of the rock from the freshly blasted face through the crushing and sorting stages to its final shipment.  Removal of soil from the surface of the trap rock prior to blasting has exposed beautifully polished glaciated surfaces. In the quarry, the vertical faces provide a clear record of what happens during the solidification of a horizontal sheet of basaltic magma and how the magma differentiates to produce sheets of ferrodiorite and granite. The main cause of differentiation will be demonstrated to result from compaction of crystal mush in the lower part of the magma sheet, with the residual liquid being expelled upward to rupture the crystal mush and form horizontal sheets of differentiated material just beneath the downward solidifying roof zone. The exposures in this quarry are of importance because if compaction of crystal mush is an effective means of differentiating a thick lava flow on the surface of the earth, it must be an important process in thicker sheets of magma cooling at depth. The excursion is planned for Sunday morning, so that people having a long way to return home can get an early start.

Departure time and location:  Assemble by 8:45 a.m. at the parking lot at the Tilcon quarry entrance on the northeast side of the intersection of Routes 80 and 22 (5 miles east of New Haven).

Contact:  Anthony Philpotts; Email: philpotts@charter.net

Limit on participants: None

C3 A New Look at the Structure and Stratigraphy of the Pomperaug Basin, Connecticut
Trip Leaders: William Burton, Philip Huber, Gregory McHone, and Peter LeTourneau

The early Mesozoic Pomperaug basin in the highlands of western Connecticut has been the focus of new mapping and research that is revealing a basin geometry and stratigraphy significantly different than that depicted on the 1985 Connecticut state geologic map. Most of the intrabasinal normal faults trend NNE, and some appear to show late, left-lateral movement based on slickenline orientations and offset of mapped contacts. Mapping in the surrounding crystalline rocks shows that the trace of the border fault south of the basin is farther west than previously shown.  New basalt geochemistry indicates that the two known Pomperaug basalts were comagmatic with the first two basalts of the Hartford basin. Chemistry and drill logs also suggest the existence of a third basalt in the basin near the eastern border fault, and present another perspective in the argument over whether the Pomperaug basin is a post-depositional, down-faulted outlier of the Hartford basin (broad-terrane hypothesis) or formed in situ via syntectonic deposition. We will visit several key localities, including the Platt Farm Nature Preserve, South Brook, and two basalt quarries where an exposed fault and spectacular examples of secondary mineralization can be found.

Departure time and location: We will assemble at 8:30 AM in the Park and Ride lot just off Exit 14 of Interstate 84, in Southbury.  Heading west on I-84, take Exit 14 (for South Britain and State Route 172), turn right at bottom of ramp onto Rte. 172, take right again at light onto Main Street South, and right again into parking lot.  Be prepared for short hikes over moderately hilly terrain and a creek traverse. Bring bag lunch, or purchase lunch when we stop at general store.  NOTE:  hardhats required for entrance into quarries; a limited number will be available.

William Burton, bburton@usgs.gov
Philip Huber, rockguy39a@yahoo.com
Gregory McHone, gregmchone@snet.net
Peter LeTourneau, letour@ldeo.columbia.edu

Contact: William Burton, U.S. Geological Survey, MS 926A, National Center, Reston, VA 20192; Phone: 703 648-6904; Email: bburton@usgs.gov

Limit on participants: None, but note hardhat requirement for quarries.

The Honey Hill fault zone marks the boundary between terranes with Iapetos affinity and Avalonian terranes across southeastern Connecticut. The tectonic history and significance of the fault zone is still a topic of debate. We will visit beautiful exposures north of the zone near Gillette Castle along the banks of the Connecticut River and south of the zone on Selden Neck, a short boat trip away. These exposures show evidence of a protracted history including ductile thrusting, boudinage, and late brittle-ductile faulting including generation of pseudotachylytes, and present-day east-west compression and related (?) seismicity of the Moodus area.

Departure time and location: 8:00 AM. at the Hadlyme ferry. From CT-9, follow signs to Gillette Castle State Park. Take the CT-148 exit 6 to Chester/Hadlyme. Go 0.3 miles and turn left at W Main St. Go 1.3 miles and continue on Water St. Go 0.9 miles and turn left at Middlesex Tpke. Go a short distance and turn right at Ferry Road. Go 0.7 miles and continue on Chester-Hadlyme Ferry. Go 0.2 miles and turn left immediatly after departing ferry on east bank, into gravel parking lot.

Details:
First stop: Lower Silurian gneisses of the Merrimack terrane (meta-sediments of the Iapetus Ocean below Gillette Castle.  Large outcrops with boudinaged pegmatites and foliation parallel pseudotachylyte layers.)

Second stop: Lower Silurian gneisses with excellent example of normal faulting preceding rotation and extension of pegmatite boudins in three dimensions.

Third stop: Boat trip to Selden Neck Island.  Outcrops (quarry) of granitic gneisses belonging to the foreign Avalon terrane.  Well developed mineral lineations and good site for collecting meta-igneous/volcanic rocks.  Discussion of contemporary ideas concerning the origin of the Honey Hill Fault zone.  Was it part of a thrust belt or did dip-slip along a low angle normal fault dominate deformation?

Contact:  Phillip G. Resor, Department of Earth and Environmental Sciences, Wesleyan University, Middletown, CT  06459; Phone: 860 - 685-3139; Fax: 860 - 685-3651; Email: presor@wesleyan.edu

Limit on participants: 24, due to use of Wesleyan boats for the third stop

This trip is designed to show the remarkable diversity of orthogneisses within the fairly limited region of the Killingworth dome in south-central Connecticut. High grade metamorphism and local anatexis of tonalitic, trondhjemitic, and granodioritic orthogneisses and metavolcanic rocks with overlapping modal mineralogies have masked surprising differences in ages and origins. Most unexpected is the discovery that rocks in the core of dome are Mississippian, apparently intruded as part of an early Alleghanian magmatic arc. Petrologic issues of anatexis, foliation development, and banding caused by either metamorphic differentiation or inherited volcanic layering (or both) will be considered in view of geochemical and geochronologic data defining plutonic and volcanic protoliths. In agreement with the geochronologic age data, Ordovician gneisses are more strongly foliated than the Mississippian gneiss in the core of the Killingworth dome. The trip will include stops to most units in the dome, as well as Gander zone rocks in the Clinton dome, and its mylonitic contact with cover Ordovician orthogneisses.

Departure time and location: Trip begins at the Park and Ride on the NW corner of the intersection of I 95 and SR 77. Assemble at 7:45 am and consolidate cars. Trip departs at 8:00 am.

Contact: Robert P. Wintsch, Department of Geological Sciences, Indiana University Bloomington, IN 47405, Phone: (812) 855-4018; Fax: (812) 855-7899; Email: wintsch@indiana.edu

Limit on Participants: None

NEIGC Site | 2005 NEIGC Program Coordinator - Mabel Peterson

NB: Questions pertaining to a specific fieldtrip should be directed to the trip's organizer(s).
General questions pertaining to the conference and registration should be directed to Mabel Peterson;
Email: mabel.peterson@yale.edu, Phone: 203-432-3166

Last Updated 9/29/2005