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Geosciences: Faculty Publications Geosciences
2004
Geology of Long Island, Bahamas: A Field Trip Guide
H. Allen Curran Smith College, [email protected]
John E. Mylroie Mississippi State University
Douglas W. Gamble University of North Carolina - Wilmington
Mark A. Wilson The College of Wooster
R. Laurence Davis University of New Haven
See next page for additional authors
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Recommended Citation Curran, H. Allen; Mylroie, John E.; Gamble, Douglas W.; Wilson, Mark A.; Davis, R. Laurence; Sealey, Neil E.; and Voegeli, Vincent J., "Geology of Long Island, Bahamas: A Field Trip Guide" (2004). Geosciences: Faculty Publications, Smith College, Northampton, MA. https://scholarworks.smith.edu/geo_facpubs/137
This Conference Proceeding has been accepted for inclusion in Geosciences: Faculty Publications by an authorized administrator of Smith ScholarWorks. For more information, please contact [email protected] Authors H. Allen Curran, John E. Mylroie, Douglas W. Gamble, Mark A. Wilson, R. Laurence Davis, Neil E. Sealey, and Vincent J. Voegeli
This conference proceeding is available at Smith ScholarWorks: https://scholarworks.smith.edu/geo_facpubs/137 Geology of Long Island, Bahamas: A Field Trip Guide
by H. Allen Curran, John E. Mylroie, Douglas W. Gamble, Mark A. Wilson, R. Laurence Davis, Neil E. Sealey, and Vincent J. Voegeli
12th Symposium on the Geologyof the Bahamas and Other Carbonate Regions
Gerace Research Center San Salvador, Bahamas 2004 COVER PHOTO: The Holocene/ late Pleistocene contact is sharp and well exposed at many places along the rocky windward (east) coast of Long Island. These cliffs are located immediately south of Coral Gardens (Stop 5). Here transgressive-phase carbonate eolianite beds of the North Point Member of the Rice Bay Formation overlie regressive-phase eolianite beds of the Cockburn Town Member of the Grotto Beach Formation. View is looking north toward Coral Gardens. Photo by Al Curran. 12th Symposium on the Geology of the Bahamas and Other Carbonate Regions
Geology of Long Island Bahamas: A Field Trip Guide
by H. Allen Curran John E. Mylroie Douglas W. Gamble Dept. of Geology Dept. of Geosciences Dept. of Earth Sciences Smith College Mississippi State University UNC at Wilmington Northampton, MA O 1063 Mississippi State, MS 39762 Wilmington, NC 28403
Mark A. Wilson R. Laurence Davis Neil E. Sealey Dept. of Geology Dept. of Biology & Environ. Sciences Media Enterprises Ltd. The College of Wooster University of New Haven P.O. Box N-9240 Wooster, OH 44691 West Haven, CT 06516 Nassau, Bahamas
Vincent J. Voegeli Gerace Research Center San Salvador, Bahamas
Production Editor: Anna M. Dustira Smith College
Copyright 2004 by the Gerace Research Center, San Salvador, Bahamas All Rights Reserved
No part of this publication may be reproduced or transmitted in any formor by any means, electronic or mechanical, including photocopy, recording, or any informationand retrieval system, without permission in written form.
ISBN 0-935909-74-5 Printed in USA
' I • •• I .·• _/ ....• ·••·• ··•••·l ._ .,, 7,4•Jtl'W 0o._• • • ,-� ...... ' · ...... THE . . �\ LIT rt.�IJ-1,. ;;_"" ;.;;_ •. .... • baco \ . - - -: E 1$. ,' BAHAMA I FLORIDA [ \�;�.• . r -�, I ISLANDS ..... Is ·:- GrancfBahama . !/ 8 -t,o . : • ·· · i �> 0 100mi. .-" ··:rt· .: .. '· ·• .. , ...•• ·• I -s, ., .. . . ••.,100 .,: ! J n ••• •• •••• •• I•• , ._.'• •• / p Mia . • • 1 • I .._-- ✓ I ;�Bimini 0... -. �-.. , 0 100km Ids. Berrt• \ ,: �:-.�· 1 "9'.,.i. .. . ·.� 0 \ . "•;_ 1 Eleuthe . Ids. �.l ,' ra "S' . . \\ .-.,"If-• ,, { ·�:-, ls ( Bathymetric contours in fathoms \ . r I j A · :.i-..,.. �'- ...... __ , \ ' . = ..,' ,.. r \' "c."I ·�=·,/l / Andros \ / .• -_ .. .•· · ·;1 {,") ts. \ \ / 'l:i� .:. 'i'o (� 1 �.·· 'r:- :n · :Q.r�fiiew • ... :1 : 'o \ m :·• ,. � , ·, Providel")C'e- ' -t--��··· : �'·· .. \ .. ''·H .l§> ! .. :. --1000 ...\ 0 .."'- '< , .. -:: :;,,,. ··.. , -..::, ...... :. 1:.. ••u••····•::: ... 0 .. ,oil>•···· o� � . , ·• ...... 1" •· , .. .,,. •• ·, • • . � � �\o . '.• :.� (<': .,...... · .... ,i.. •.. •··· \ ' • ,;,. •� f : + ,:. cat Is / l · ,j,�"!J • . · I � •••._ •,-. . I I ,,;, . • •• . •• ' c-:,'-<;. � ' �'c, • •• ,.. I \ '· �.. ..\ \• '\ ','J) ·· � I ., ' ·, •��\ . . ./ '\�� \ _.-•··•. '.I . h � {..�· ·,; \ ·· ·· � . . /�-:'- SAN SALVADOR _. . - · ·-..•. �'· .• · · rong. .. �·oo'N � �,.. \ · • -.....uc...... ot ..... �.: ..,. ..'·· • ,� ..... i Qay Sal \ ·,• � 11,e ocean,� � �· �---�,,, -',, r.. •...... ,., , , ", _ (!!!; -:, IS. .··• ... , �'·•...... ,· �. ..-..._ \' ' , 1 \. Bank \\ ·�-, \ • ...... •◄, o,. "'· ,._ .... ./ \, 'RtJm' ' ······• .: Great •· · .,_ \ , � 100. . •····•.. .r-. Cay .• ··�.} 4JY Exuma ,.,
INTRODUCTION
The purpose of this field guide is to Columbus Monument describe and illustrate some of the well exposed LONG ISLAND and most interesting geological sites on the north THEBAHAMAS end of Long Island, Bahamas. Long Island is one of the Bahamian "Family Islands" or "Out Islands," and it has a population of about 4,000 inhabitants. The north end of the island lies ATLANTICOCEAN about 270 km southeast Nassau, the capital city of The Bahamas, located on New Providence Island (Figure 1 ). Life on scenic Long Island is tranquil and community oriented. The island has a past history of salt production by the now defunct Diamond Salt Company. Sponging still operates on a small scale, and tourism and its related activities is growing. Originally named Fernandina by Christopher Columbus, in honor of his Spanish king mentor, the island takes its present name O kllom eters 20 from its geographic form. It truly is a long island, extending for about 120 km in length, but with a width of no more than 7 km at the widest Figure 2. Overview map of Long Island. The Tropic point (Figure 2). The late Quaternary, all of Cancer crosses the island just south of Stella carbonates geology of Long Island is varied and Maris. Cartography by Doug Gamble. spectacular. This field trip is restricted to the north end of Long Island, given that only part of presented in the text. We are guests on Long one day is available for our geologic Island, and all field trip participants are urged to reconnaissance. We hope that this field guide treat the areas we visit with the utmost respect. and trip will pique interest in the geology of It is illegal to undertake scientific research in Long Island and serve as a catalyst for future The Bahamas without a research permit. geologic investigations over the greater extent of the island. Many of the sites we will visit are on PLEASE DO NOT MAKE SAMPLE private or restricted landsand special permission COLLECTIONS AT ANY STOP WITHOUT is necessary for entry to some of these areas. For ASKING THE FIELD TRIP LEADERS IN these reasons, it may not be possible for ADVANCE. WE REQUEST THE SAME someone who is using a copy of this fieldguide RESPECT FOR PRESERVATION OF at a later date to follow precisely in our THESE GEOLOGIC SITES FROM ALL footsteps. Last-minute changes owing to SUBSEQUENT USERS OF THIS weather conditions or time constraints may result GUIDEBOOK. in our field trip taking alternate routes and visiting a slightly differentselection of sites than
1
REGIONAL SETTING Masaferro (1997), and Manfrino and Ginsberg (200 I) has demonstrated that the Bahama banks The Bahama Islands comprise a 1,000 are undergoing both depositional progradation km long portion of a NW-SE trending and erosional segmentation. archipelago that extends from Little Bahama The geologic literature on the Bahamas is Bank off the coast of Florida to Great Inagua extensive, but the bulk of that literature deals Island, just offthe coast of Cuba (Figure 1). The with the carbonate banks and related deep-water archipelago extends farther southeast as the environments. With the exception of San Turks and Caicos Islands, a separate political Salvador, comparatively little work has been entity, and terminates with Silver Bank and done on the subaerial geology of other Bahamian Navidad Bank. The northwestern Bahama islands. The first geologic map of a Bahamian islands are isolated landmasses that project island was not published until Titus' work on San above sea level from two large carbonate Salvador in 1980 (Titus, 1980). Hutto and platforms, Little Bahama Bank and Great Carew (1984) on San Salvador, Garrett and Bahama Bank. To the southeast, beginning in Gould (1984) on New Providence, Carew and the area of San Salvador Island, The Bahamas Mylroie (1985) on San Salvador, Wilbur (1987; comprise small isolated platforms capped by 1991) on Little San Salvador and West Plana islands that cover a significant portion of the Cay, Carew and Mylroie (1989a) on South available platform area. The Bahamian Andros, and Kindler (1995) on Lee Stocking platforms have been sites of carbonate Island, represent some of the initial attempts to deposition since at least Cretaceous time, provide geologic descriptions of whole islands. resulting in a minimum sedimentary cover A thorough overview of Bahamian island thickness of 5.4 km (Meyerhoff and Hatten, geology can be found in Curran and White 1974) and perhaps as much as 10 km (Uchupi et (1995). al., 1971). The large platforms to the northwest are dissected by deep channels and troughs SUBAERIAL GEOLOGY OF THE (Figure 1 ), whereas the isolated platforms of the BAHAMAS southeastern Bahamas largely are surrounded by deep water. Water depths on the platforms are The exposed rocks of The Bahamas are generally less than 10 meters. all late Quaternary carbonates, dominated by The origin of the Bahama platforms has subtidal facies at low elevations and by been the subject of much debate, from which two eolianites at elevations above 6 m. Paleosols can main theories have evolved. Mullins and Lynts occur at all elevations. The glacio-eustatic sea (1977) proposed a "graben" hypothesis, which level changes during Quaternary time alternately explains the current configuration of the Bahama have flooded and exposed the Bahamian Archipelago as the result of plate tectonic motion platforms, subjecting them to cycles of carbonate that produced the opening of theAtlantic Ocean deposition and dissolution, respectively. in the Mesozoic. The pattern of banks, troughs Significant carbonate deposition has occurred in and basins is explained as resulting from an the past only when the platforms are flooded, as initial horst and graben pattern consistent with is increasingly the case today. continental rifting. The competing theory is the The carbonate sequences of the Bahamas "megabank" hypothesis (Meyerhoffand Hatten, can be viewed as individual packages deposited 1974; Sheridan et al., 1981; Ladd and Sheridan, on each sea level highstand, separated by 1987), which holds that the modem Bahamas are erosional unconformities (usually marked by a segmented remnant of a much larger and paleosols) produced by each sea-level lowstand continuous Mesozoic carbonate platform. (Carew and Mylroie, 1995a; 1997). Each Recent work by Eberli and Ginsberg (1987), depositional package consists of three parts: a Mullins and Hine (1989; 1990), Melim and transgressive phase, a stillstand phase, and a 2 regressive phase. These phases each contain a AGE LITHOLOGY MEMBER FORMATION MAGNETOTYPE subtidal, intertidal, and eolianite component. H 0 -�·,-:---...,- --:----'•, HANNA BAY Holocene sea level is sufficientlyhigh so that the :�...... _.'· MEMBER L .':::::-:-...... ______only marine deposits exposed on land today are 0 ·- RICE BAY C '- ,. . FORMATION ...... --�-' �'--- ...... _'. those associated with the high stillstand phase of E � •,•\. NORTH POINT N -�-�� MEMBER E ·'���\:,. '··-- . ' '·'· oxygen isotope substage Se, about 130,000 to ,�,,.\.,.-,'. ,. FERNANOEZ BAY 119,000 years ago (Chen et al., 1991). At its ...... _-..::::_ �..... maximum, sea level was about 6 m higher than COCKBURN at present. The transgressive and regressive '-'' TOWN //�✓/;,//;/ MEMBER p Jt'-",,('/·".,,- � . GROTTO marine deposits of substage Se are below modem L BEACH E FORMATION sea level, and the stillstand subtidal deposits of I · _.:. : . �lv:·.1 _:·. sea-level highstands prior to those of substage Se s T ��,; FRENCH BAY also are not visible. Given isostatic subsidence 0 '-f{J'j�/ (//7 }/ MEMBER rates of 1-2 m per 100,000 years (Mullins and E /{//;/4 N GAULIN CAY Lynts, 1977; Carew and Mylroie, 1995b), earlier E highstands were either not high enough, as for :-0�"" UPPER OWL'S HOLE FORMATION stage 7, or if high enough, occurred too long ago, " ;::-. "" >---' SANOY POINT PITS LOWER OWL'S HOLE FORMATION as for stage 9 and earlier, to generate deposits ���� above modem sea level. In contrast, eolianites Figure 3. The Carew and Mylroie stratigraphy of the form topographic highs that extend well above Bahamas, updated and modified from previous past and modem sea levels, so eolianites from versions as cited in the text. several highstands are widely exposed on Bahamian islands. Bahamas today represent deposition during that During transgression, carbonate small fraction of the time when sea levels were sediments are deposited when bank tops flood, high enough to flood the banks and tum on the and beach sediments are continually remobilized carbonate sediment factory. by the bulldozing action of the advancing sea. In the Bahamas, the most complete Large dunes are formed, which may be sequence of deposits representing a subsequently attacked by wave action as sea transgression, stillstand, and regression cycle is level continues to rise. Only the largest or most the depositional package formed during the favorably positioned transgressive eolianites oxygen isotope substage Se event. Older survive the rise of sea level to a maximum. packages are incomplete, for the reasons given During the stillstand of a sea-level high, subtidal earlier, and the Holocene package does not, as and intertidal facies are deposited, but as the yet, contain a true regressive phase (although it system reaches equilibrium, eolianite production does contain progradational regressive deposits). is probably less than during transgression. A general model for the development of During regression stillstand subtidal deposits are the stratigraphy of Bahamian islands was first reworked by beach processes, and substantial proposed by Carew and Mylroie in 1985. This eolianite packages can be formed. These model was developed using San Salvador Island regressive eolianites are abandoned by falling as the specific example, but it has been sea level. As sea level moves offthe platform, successfully transported to other islands by erosional forces take over and soils are produced Carew and Mylroie (1989b) and by other that will eventually be preserved as paleosols. It workers (Wilbur, 1987, 1991; Kindler, 1995). is important to recognize that during the The model has been modified with the Quaternary, the Bahamas have been in a sea accumulation of new data (Carew and Mylroie, level lowstand condition as a result of glacio 1989b; 1991; 1995a; 1997). A stratigraphy eustasy for about 85 to 90% of the time. The developed fromthis model is presented in Figure Quaternary carbonate units seen exposed in the 3, and it is the basis for the stratigraphic 3 assignments and descriptions given in this field The older French Bay Member is a transgressive guide. This stratigraphy is based on field eolianite (Carew and Mylroie, 1985; 1997). In relationships, and does not require the use of some places, transgressive eolianites are marked geochronological tools, although it subsequently by an erosional platform on which later stillstand has been substantiated by a number of fossil corals are found (Halley et al., 1991; geochronologic methods (Carew and Mylroie, Carew and Mylroie, 1995a). The Cockburn 1987). A spirited debate developed in the 1990s Town Member is a complex array of stillstand about Bahamian stratigraphy (see Carew and subtidal and intertidal facies overlain by Mylroie, 1997, and references therein) centered regressive eolianites. In earlier versions of the on the reliability of amino acid racemization Carew and Mylroie stratigraphic model (Carew (AAR) analyses for making stratigraphic and Mylroie, 1985; 1989b), the Grotto Beach subdivisions in the absence of evidence provided Formation also contained the Dixon Hill by field relationships. Member, thought to represent an eolianite The eolianite packages older than oxygen deposited during oxygen isotope substage Sa isotope substage 5e were initially lumped about 85,000 years ago. This member, based together as the Owl's Hole Formation, although solely on amino acid racemization data, proved it was recognized at the time that this unit incorrect (Carew et al., 1984), and it was probably contained eolianites from a number of subsequently eliminated from the stratigraphy pre-substage 5e sea-level events (Carew and (Carew and Mylroie, 1995a; 1997). During Mylroie, 1985). AAR data were subsequently Grotto Beach time, ooids were produced in great used to subdivide the Owl's Hole into multiple numbers, and the vast majority of eolianites in units on San Salvador Island (Hearty and the Grotto Beach Formation are either oolitic or Kindler, 1993). While AAR data were contain appreciable ooids. considered controversial, it was later established Another debate concerning Bahamian on Eleuthera Island that subdivisions of the geology involved the existence of oxygen Owl's Hole could be demonstrated in the field isotope substage 5a eolianites (see Carew and (Kindler and Hearty, 1995; Panuska et al., 2002). Mylroie, 1997; Kindler and Hearty, 1997 and Paleomagnetic analysis of the secular variation references therein). As noted above, AAR data in paleosols also indicated that the Owl's Hole were used to create a substage Sa eolian unit in could be subdivided into an upper and lower unit 1985 (Carew and Mylroie, 1985), but that unit on San Salvador Island (Panuska et al., 1999). was dropped when fieldwork demonstrated that However, secular variation analysis is not field the unit in question was older than substage Se evidence, and there are no subtidal units in this (Carew and Mylroie, 1997), and laboratory tests formation. The eolianites of this unit are indicated use of the land snail Cerion for AAR predominantly bioclastic, and ooids are work was extremely unreliable (Mirecki et al., extremely rare. The Owl's Hole Formation is 1993). However, use of whole rock AAR usually recognized in thefield by its relationship analysis was argued to avoid this problem and to overlying deposits. Efforts to subdivide units was used to identify substage Sa eolianites on a in the Bahamas by petrologic methods have been number of Bahamian islands (Kindler and attempted (e.g. Kindler and Hearty, 1996; 1997), Hearty, 1997 and references therein), including but demonstrated petrologic variability among Long Island. No field evidence has been single Pleistocene units, as well as in Holocene established to demonstrate,one way or the other, units, indicatesthat this technique is not reliable. that substage Sa units exist in the Bahamas. Overlying the Owl's Hole Formation, and However, AAR data have been used to identify separated from it by a paleosol or other erosion substage 5a eolian units on Bermuda (Vacher surface, is the Grotto Beach Formation. This and Hearty, 1989). formation was deposited during oxygen isotope Overlying the Grotto Beach Formation substage 5e, and it consists of two members. and separated from it by a paleosol or other
4 erosion surface are the rocks of the Rice Bay Formation, deposited during Holocene time. TABLE 1. PHASES OF DEPOSmON AND The Rice Bay Formation also is divided into two DIAGNOSTIC CHARACTERS members based on their depositional history Transgressive Phase Stlllstand Phase Regressive Phase ' . relative to Holocene sea level. The North Pomt Fine-scale eolian bed- Disrupted eolian bed- Disrupted eolian bed• Member consists entirely of eolianites, whose ding ding ding foreset beds can be followed at least 2 m below Few vegemorphs Abundant vegemorphs Extensive vegemorphs Penecontemporary Penecontemporarynotch· Lack of penecontem modem sea level in some places. Whole rock chlflng and boulder ing of beach and Intertidal porarywave erosion carbon-14 measurements from the North Point paleotalus facies. and beach-lace Member indicate ages centered around 5,000 breccia facies Laterally adjacent, but rarely in an Penecontemporary Rare sea caves Lack of sea caves yBP. sea caves overlying position, is the younger Hanna Bay Corals on wave-erod- No corals on eroded No penecontempo- Member. This unit consists of intertidal facies ed benches benches rary benches and eolianites deposited in equilibrium with Lack of protosols Protosolscommon Protosols common modern sea level. The eolianites have a On lapped still-stand Marine facles abundant Commonly peleoidal/blo• or regressive-phase elastic radiocarbon age centered around 3,000 yBP, but deposits some beach rock has ages as young as 400 yBP Predominantly eolian- Ebb-tidal delta, lacus- Eolianites overstep- (Carew and Mylroie, 1987). While weakly ites, marine deposits trine, and strand plain ping marine deposits developed ooids have been reported from the rare deposits early stages of North Point Member deposition (Carney and Boardman, 1991), the Rice Bay Formation exposures on San Salvador are Holocene unit overlying Pleistocene rocks. The predominantly peloidal and bioclastic. The Pleistocene unit in most such cases of North Point Member is now being attacked by Holocene/Pleistocene contact is believed to be wave erosion. Sea caves, talus, and coral the regressive-phase eolianites of the Cockburn communities on wave-cut eolianite benches of Town Member of the Grotto Beach Formation. the North Point Member exist, as mentioned Identificationof regressive- versus transgressive earlier for the rock record of the French Bay phase eolianites can be determined following Member of the Grotto Beach Formation criteria established by Carew and Mylroie (1995; 2001), as shown in Table 1. GEOLOGY OF LONG ISLAND The Grotto Beach Formation/Owl's Hole Formation contact has not been located, and the Although field work in 1990 existence of Owl's Hole rocks is only indirectly demonstrated the many aspects of the karst demonstrated by virtue of hosting mature karst geology of Long Island (Mylroie et al., 1991), features. The trip stops will follow the systematic study of the overall carbonate stratigraphic column of Figure 3 downward, geology of the island has not yet been done. starting with Holocene units and then moving to This field guide is the first published use of a the late Pleistocene units. A brief one-day field Bahamian geologic model on Long Island. The trip simply cannot cover the geology of the field trip stops will show examples of the Rice entire island, but we think that the stops selected Bay Formation, including an excellent exposure forthis trip do offera representative overview of of the Hanna Bay Member/North Point Member the Quaternary geology of Long Island. contact, not commonly reported elsewhere in the Furthermore, we hope that these stops will spur Bahamas. The Rice Bay Formation/Grotto comment and discussion and will demonstrate Beach Formation contact is well developed and how the stratigraphic modelpresented earlier can frequently exposed on Long Island, with the be applied to Long Island. North Point Member generally being the
5 Carbonate Island Karst Model Common attributes that distinguish Island karst Distinct geomorphic types that distinguish from karst of Interior settlnas carbonate Islands from one another Simple Carbonate Islands: Non-carbonate The karst is eogenetic. rocks remain below the zone of fresh-water influence, and recharge is exclusively autoaenic. (Fia. 4a) Dissolution is enhanced at the surface, bottom, and margin of the freshwater fens Carbonate Cover Islands: Non-carbonate by mixing of waters and trapping of organic materials at these boundaries. basement rocks deflect percolating water and oartition the fresh-water lens. (Fia. 4b) Gfacio-eustatic sea-level fluctuationsimpose dlssolutional and dlagenetic imprints Composite Islands: Non-carbonate basement reflecting the vertical migration of the lens. exposed at the surface, and allogenic recharge is delivered to insurgences on the contacts. (FiQ. 4c) Tectonic upliftand subsidence overprints the glacio-eustatic imprints with Complex Islands: lnterfingering of additional dissolutional and diagenetic imprints, as well as structuralmodifications carbonatelnon-carbonate facies and faulting combine to produce complex aquifer features. (Fig. 4d) Table 2. The Carbonate Island Karst Model (CIKM). Modified from Vacher and Mylrole, 2002.
cumulative dissolution and collapse that has FRESHWATER LENS HYDROLOGYAND occurred during many sea-level fluctuations. KARST PROCESSES The complexity of cave passages found in blue holes is the result of overprinting of repeated In any essentially homogeneous body of marine, freshwater, and subaerial conditions rock like that of the carbonates forming the throughout Quaternary time. Conversely, the Bahamian islands, the freshwater lens floats on presently dry caves of The Bahamas formed underlying, denser seawater that permeates the during the relatively short time periods of the subsurface. The model for the ideal behavior of late Pleistocene when sea level was higher than such water masses is the Ghyben-Herzberg at present. Bahamian caves that formed above Dupuit model. In reality, variations in rock modern sea-level elevation prior to oxygen permeability and other factorsresult in distortion isotope substage Se time today lie below modern of the ideal lens shape (e.g. Vacher and sea level owing to isostatic subsidence of the Bengtsson, 1989). Nonetheless, the Ghyben platforms (Carew and Mylroie, 199Sb). Taking Herzberg-Dupuit model serves as a useful first isostatic subsidence into account, sea level was approximation of the relationship between the high enough to produce the observed subaerial freshwater and underlying marine groundwater caves for a maximum of about 11,000 years of in an island. the oxygen isotope substage Se time period. In During past higher stands of the sea, the addition, during that sea-level highstand, only fresh groundwater lens in each island was as the eolian ridges and a few beach and shoal high or higher than it is today. Beneath the deposits stood above sea level, and island size in surface of those past freshwater lenses, within The Bahamas was dramatically reduced the limestone rock of the islands, caves were compared to that of today's islands. As a produced by dissolution. Each time sea level consequence, freshwater lens volumes and fell, the caves became abandoned and dry. discharges were comparably reduced. An end Under today's climatic conditions the Earth is result of this scenario is recognition that dry warm and sea level is relatively high, but not Bahamian caves represent development during a quite as high as at some times in the past. We very short time period within small freshwater can therefore enter dry caves today throughout lenses and with minimal overprinting by later The Bahamas. In contrast, the blue holes of The events. Any model that attempts to explain Bahamas lead into caves that are flooded by development of these caves must operate under seawater. These blue holes represent the these tight constraints of time and space. 6 carbonate and non-carbonate rocks (Figure 4) is A SIMPLE CARBONATE ISLAND also crucial. This last item has little meaning in The Bahamas, as these islands are 100% carbonates. FLANK MARC.INCAYE DEVELOPMENTAT THt·tt.NSMARCilN The youthfulness of Bahamian carbonate \..\JIU(N.\rE"""' rocks creates different water-flowdynamics than t /\VEDEVELOPMENT AT THE H/\UX.1.INE are found in the dense, diagenetically-mature B CARBONATE-COVER ISLAND carbonates of continental interiors. The AlTTtXialtcREC AllliE H Bahamas exemplify what has been described as eogenetic karst, defined by Vacher and Mylroie + + (2002, p. 183) as "the land surface evolving on, A F. H C ��:=���J � CAROO NATE + :���:� + and the pore system developing in, rocks + ... + undergoing eogenetic, meteoric diagenesis." + + + + The term "eogenetic" was taken from Choquette COMPOSITE ISLAND and Pray (1970, p. 215) who defined the three C AUTOOENK." AllOCiENK."RECHARGE RE{ltARUE time-porosity stages of carbonate rock evolution: "thetime of early burialas eogenetic, the time of deeper burial as mesogenetic, and the late stage associated with long-buried carbonates as + + + + telogenentic." Eogenetic carbonate rocks have !«JM.('AHOSAlt + + O 7 Figure- 5. Interior of Salt Pond Cave, Long Island. Figure 6. Segmented interior of Hamilton's Cave on Photo by JohnMylroie. Long Island. Photo by JohnMylroie. The term "blue hole" has been used in a Dean's Blue Hole on Long Island is known to be variety of ways. A complete review of the over 200 m deep, ending in a vast chamber history of blue hole studies, and the various uses (Wilson, 1994). Blue holes commonly lead into of the term, can be found in Mylroie, et al. major horizontal cave systems, such as Lucayan (1995). Blue holes are defined as: "subsurface Caverns on Grand Bahama Island, and Conch voids that are developed in carbonate banks and Blue Hole on North Andros Island. islands; are open to the earth's surface; contain This field trip will visit a single blue hole tidally-influenced waters of fresh, marine, or of relatively average characteristics (Stop 7). mixed chemistry; extend below sea level for a Dean's Blue Hole is too far south, and too majority of their depth; and may provide access remote, for access by this field trip. Blue holes to submerged cave passages." (Mylroie, et al. are varied and interesting, and there has been 1995, p. 225). Blue holes are found in two much discussion about their origin, definition, settings: ocean holes open directly into the and exploration. Such discussions likely will present marine environment and contain marine continue during this field trip and at the 12th water, usually with tidal flow; inland blue holes Geology Symposium. The field trip also will are isolated by present topography from marine visit a flankmargin cave, which developed in the conditions, and open directly onto the land discharging margin of a past, higher elevation surface or into an isolated pond or lake, and freshwater lens, just under the flank of the contain tidally-influenced water of a variety of enclosing eolian ridge (hence the name "flank chemistries from fresh to marine. The most margin cave"). Eogenetic karren will be seen at common alternative use of the term "blue hole" a number of field trip stops, both inland and is to describe large and deep karst springs coastal, and will be briefly presented and (Mylroie et al., 1995). discussed. Long Island has some of the largest In thenorthwestern Bahamas, blue holes known flank margin caves in the Bahamas, such with depthsin the 100-125 m range are common, as Salt Pond Cave and Hamilton's Cave. These and it was thought that their depth was limited caves exhibit large chambers, some of which are by the position of the lowest glacial sea-level intact (Figure 5) and some that are segmented lowstand, which was about 125 m below present (Figure 6). A complete discussion of these sea level. However, exploratory wells caves, and others is given in Mylroie et al. commonly intersect voids below that depth (e.g. (1991). depths of 21 to 4082 m; the deepest of these voids was large enough to accept 2,430 m of broken drill pipe [Meyerhoffand Hatten, 1974]). 8 • ��--·.:-:-�l\:�-���-��·;._:7_. .. .. - >·•.>:� -�-� - . -.._:;. _�:i>i�:::���7-=-.;�. �� �� =���r,�,v :.;.;._ - ,'.l.-#._• _..f' Figure 9. (Left) Exposure of North Point Member at the south end of Stop 1. The lowermost beds of this exposure exhibit unusual characteristics as described in the text. Scale = 1 m. Photo by Mark Wilson. Figure 10. (Above) Close-up of the lower beds shown in Figure 9. Note the pillar-like erosional form of these beds and the vertical cylindrical holes. Photo by Mark Wilson. 12), along with other mesoscale bedding features. This surface also commonly exhibits that they do not show strong eolian bedding, troughs with lithified breccia-block fill (Figure displaying instead a general lack of bedding and 13). The modem processes of coastal erosion a spongioformtexture. Furthermore, these beds and deposition that can be observed along this contain distinctive vertical and long cylindrical section of coast provide good explanations for holes of several to 15 cm or more in diameter, many of the features foundpreserved within this and thebeds erode to create an overall pillar-like Hanna Bay Member surface. form (Figure 10). A similar example of this Continuing north a few tens of meters, it North Point Member facies will be seen at Stop can be seen that the Hanna Bay Member overlies 3, and further discussion is presented with that another unit dipping landward, with the planar stop description. The details of the Hanna Bay beds lying unconformably on subenvironment and processes of deposition truncated eolianite beds. There is no paleosol at represented by these beds have not yet been fully theunconformity, and the beds of the lower unit developed and should provide a point for lively dip below modem sea level. The lack of a discussion during the fieldtrip. paleosol on top of the lower unit is again an Now head north along the coast and indication of Holocene age, and the dip of the around a rocky headland. Here a series of planar eolian beds below sea level confirms beds can be seen dipping asymptotically toward identification of the North Point Member of the modem sea level (Figure 11 ). Again, the lack of Rice Bay Formation. The lower HannaBay beds a paleosol on this surfaceindicates that the rock contain clasts of North Point material as a rubble is Holocene in age, and its congruency with layer at the contact. A short distance north from modem sea level identifies theunit as belonging this point, a field of boulders, mostly from the to the Hanna Bay Member of the Rice Bay Holocene units, lies at the base of the Holocene Formation. Ripples are well preserved (Figure rock cliffs. Farther north, the unconformity re Figure 12. Wind ripples preserved in the planar Hanna Bay Member beds, Stop 1. Scale= 15 cm. Photo by John Mylroie. r:,;> � "" ... 1 • •"/...f ,✓ • L •� � �;J', : � :� / . �· . .._;·,Ji% ': >;; ���==�� ;�'.._;, :1 -;.,f(. . '. ' �·�.,-,,:? ·I,,. ,,::,_•· ,,./. j .;� . ·,:! >·,.; r'�' ,. . ,... ,. • ..• .I �,. ; !7! !J' . , �,r..-J , : ! . � '\1(.t_� •-.:.i - •·•',#J. •,tf •• :·•• • : ✓,:: t, r�•-t' Figure 13. (Above) Breccia-block fill in troughs of the Hanna Bay Member beds,Stop 1. Pen= 15 cm. Photo by Al Curran. Figure 14. (Right) North end of Stop 1, with seaward-dipping North Point Member beds in foreground and boulder field and Holocene/Pleistocene contact in background. Photo by John Mylroie. Figure 15. Numerous specimens of fossil Cerion preserved in Figure 16. Root casts or rhizomorphs at Stop 2. Scale = 15 cm. the paleosol at Stop 2. Scale= 15 cm. Photo by John Mylroie. Photo by John Mylroie. 11 � z::::, (Section unevenly eroded at top) t----t--t,;. ....w wz u 0 ...J Skeletal gralnstone with 0 open cylindrical structures 4 and spongioform texture 1m Calcrete crust on paleosol Skeletal grainstone with large Cerionsp. (Eroded bench at beach level 1 Figure 19. Generalized stragtigraphic column across !}8 -• • _ :·11.;'�-� · __:?.�::Jtf( the Pleistocene/Holocene contact at Stop 3, on the ',,�A � �� �-.,·� t��:�Jtt�f \ north side of Cabana Beach and immediately past the ' ..�..(• ,,�• "r�zt' �.. ��:. ... :-..�"· •.�::"!1\{i,':" Figure 18. A: The late Pleistocene/Holocene section, boulder rip-rap. Section by Mark Wilson, Al Curran, north side of Stop 3. Mark Wilson's rock hammer is and Drew Feucht. at the contact, on top of the hard caliche layer. B: Close-up of the caliche layer, grading downward into inverted, and what was the bottom of small pits paleosol material containing Cerion fossils and now are the tops of small pillars. A number of pisolites. Hammer = 26 cm. Photos by Al Curran. large boulders also are present in this area. Several of the bigger ones exhibit a thick rind of there are numerous little pillars, from 10 cm to 1 vermetid-snail encrustation, along with the m high. All are capped by dish-shaped crusts of remains or traces of other encrusters, indicating resistant paleosol (Figure 17). Prior to the that the boulders once were subtidal or intertidal Holocene rise in sea level, this region was an and have been transported and deposited by epikarst or karren surface, with numerous small wave action. dissolution pits. These pits collected soil, which Head back north across the cabana beach hardened into a resistant paleosol. As waves and move past the boulder rip-rap to where true initially commenced eroding this area ~3,000 outcrop begins. This exposure presents a great years ago, the surface began to be strippedaway. close-up view of the late Pleistocene/Holocene The paleosol crust was thickest and most contact, as shown in Figure 18A and in the resistant at the bottom of the small pits, and so stratigraphic column of Figure 19. Notice that withstood the erosional stripping of the surface the late Pleistocene beds contain numerous fossil around them. As a result, the topography is Cerion shells identical to those found at Stop 2. 13 STELLA MARIS CAVE LONG ISLAND, BAHAMAS J. E. MYLROIE & J. L. CAREW COMPASS & TAPE JUNE 1◄, 1990 B' ___, Figure 22. Interior of the "Party Cave" circa 1990. Photo by John Mylroie . karren, the result of meteoric water dissolving N the upper few meters of rock. There is debate about how much of this rock exposure is natural, 0 and how much is the result of soil loss through O mag1 5 meters agricultural practices (mostly slash and bum). Clearly the rock looks like Swiss cheese, and gives the impression of high porosity at depth. But the greater part of this porosity disappears with in a meter or two of the surface. This can be observed in the cave, as the ceiling is largely Figure 21. Map of Stella Maris "Party Cave." solid without nearly as many holes as were seen on the surface a few meters above. The epikarst the saltwater wading pool and beyond. We will is a thin but very permeable region that acts to not have time today to investigate these create a perched aquifer. Vadose flow is by exposures, so save them for your next trip to percolation, or by moving laterally and Long Island. Return to the bus and re-board. descending through vadose fast-flow routes, or Depending on the time, we will make our lunch pit caves. A few of these features can be seen stop next or immediately afterStop 4 . entering the cave ceiling. The "Party Cave" hosts the weekly Stella Stop 4 - Stella Maris Party Cave: From Stop Maris Resort barbeque. In 1990, it was mapped 3, continue north to the second left-hand tum as Stella Maris Cave (Figure 21). When first heading west and uphill (the first left-handturn entering the cave, a small boat is seen, and it is not a through street). Go uphill and take the serves as the party bar (Figure 22). second left, and about 100 m to the south, on the This is a classic flankmargin cave, with a west side of the road, is a sign marked "Party single globular main chamber, along with short Cave" and a place to pull offthe road. Exit the passages offthe sides and rear that quickly end. bus and follow the paved path downhill to the The cave was a mixing chamber, and water south, and continue as it hooks left (west) and entered and exited as diffuse flow, while fresh leads to a large cave entrance. water/sea water mixing created substantial While on the path, note the many dissolution at the lens margin. The position of dissolution holes and pits in the rock on either the cave in the distal margin of the fresh-water side of the path. This is the epikarst or surface lens means that it formed under the flank of the 15 . •I f�. i;,'t;_ :,•�r ., --·· . � ,�·��· - �:.__ _ i - . --. -. ·• ,,. r,. . " Figure 23. Holocene North Point Member beds overlying Figure 24. Fossil Diploria clivosa coral colony in subtidal late Pleistocene Cockburn Town Member rocks at Stop 5. beds of the Cockburn Town Member, Stop 5. Scale= 15 Photo by John Mylroie. cm. Photo by John Mylroie. Figure 25. Beds of the CTM Member subtidal facies Figure 26. Overview of the blue hole, Stop 6. Photo by overlying truncated eolianite beds, probably representing John Mylroie. the French Bay Member, Stop 5. Photo by John Mylroie. :'l --��, -J!J';..1 Figure 27. The Pleistocene eolianite ridge of Stop 7. Figure 28. Exposure of Holocene North Point Member Photo by John Mylroie. eolianite, viewed fromthe coast on the east side of Columbus Monument hill. Photo by John Mylroie. 16 land mass. With present sea-level conditions, late Pleistocene rocks (Figure 23 and the the cave is dry, and the cave's position made it guidebook cover photo). In this case, it is clear vulnerable to hill slope and scarp retreat, which that these rocks are Cockburn Town Member have breached the cave to the surface. Without subtidal facies and regressive-phase eolianites. this secondary erosion, the cave would have no At the shoreline cliff, in isolated localities, are natural entrance. fossilcoral colonies (Figure 24); West Indian top Flank margin caves are excellent shells are also present, along with other indicators of sea-level position, as the fresh molluscan fossils. Subtidal facies above modern water lens is controlled by the location of sea sea level in the Bahamas are virtually always level. As in most caves, secondary subaerial indicative of the CockburnTown Member of the calcite deposits, primarily stalagmites, are found, Grotto Beach Formation. A few meters to the and they can be used forage-dating by the U/Th south, the subtidal units can be seen to overlie a method. These data give limits as to when the truncated eolianite (Figure 25). The absence of a cave could have formed ( e.g. Carew and paleosol at this locality suggests that the lower Mylroie, 1995b ). Stable isotope analysis also eolianite is the French Bay Member of the can provide information on past climate Grotto Beach Formation, but the wave action conditions. that planed offthe eolian surface possibly could Because the Stella Maris Cave had to have removed a paleosol, in which case the have formed on a previous glacio-eustatic sea lower unit would be Owl's Hole Formation leve l highstand, the eolianite the cave is eolianite. Returnto the bus and re-board. developed in had to be already present. For many reasons (e.g. Carew and Mylroie, 1995b), Stop 6 - Blue Hole: The bus will head a short the cave most likely formed during oxygen distance north (about150 m) and take a right turn isotope substage Se. The eolianite is therefore onto a dead end road. From the dead end, a trail probably Owl's Hole Formation, although it leads down slope to the edge of a large blue hole could be French Bay Member of the Grotto (Figure 26). This trail is steep in places, and Beach Formation. In the latter case, the eolianite space at the bottom is small, so maneuver would have formed on the transgression, the carefullyto fiteveryone in. fresh-water lens would have entered the eolianite This is a large blue hole surrounded by as sea level reached its peak, pushing the fresh low rock cliffs. The cliffs are highest to the water lens into the dune, and forming the cave north side, and the deepest point is below the by dissolution. Exit the cave and return along highest cliff. The salinity is normal marine. the pathto re-board the bus. This blue hole has many fish, and also turtles, which indicates a connection to the sea, although Stop 5 - Coral Gardens: From the "Party the turtles likely have been introduced. As noted Cave", reverse direction, return to Ocean View in the Introduction, blue holes are polygenetic, Drive, and tum left (north) onto the drive. forming from flooding by glacio-eustasy of Follow the coast road north forabout 1 km; after vadose pit caves, by collapse of deep-seated about 2/3rds of a km the road will angle inland dissolutional chambers, or by bank-margin to the northwest. Go past one turn to the right, failure. The large size and circular shape of this take the second tum to the right, and head blue hole indicate that it most likely formed by northeast back towards the coast. The road ends collapse of a deeper void, with subsequent retreat at a T-intersection. Exit the bus, and follow the of the bedrock perimeter. Blue hole water trail down to the coast to the Coral Gardens (a chemistry can be complex, fromfresh to marine fringingoffshore ree f). to hypersaline. Blue hole biota can be similarly The rocky bench here is much like what complex, especially in terms of microbial was seen at Stops 1, 2, and 3. Exposed are activity. Scramble back up the trail, and re Holocene dunes (North Point Member) overlying board the bus. 17 phase beds of the Cockburn Town Member . Looking west, the Columbus monument stands forlorn. In 1990, it looked much better (Figure 30). Farther to the west, lower eolianites with a paleosol surface can be seen (Figure 31); this is the Pleistocene foundationupon which the North Point Member eolianites rest. The significance of this outcrop is that it gives evidence of the prodigious allochem production that occurred as the Bahama banks were initially flooded coming out of the last glaciation, as the carbonate factory was turned on. All of the North Point Member eolianite seen here was produced in at most :I.,.· 2,000 years. Returnto the bus and re-board. Figure 32. Low Holocene dunes of the strand plain at Stop 9. Pack forscale. Photo by Al Curran . Stop 9 - Stella Maris' Santa Maria Beach Reserve: Return to the main paved road in sea level. This indicates that these dune and Seymour Settlement. Drive a short distance backshore beds should be assigned to the Hanna south (about 0.75 km) and make a right turn to Bay Member of the Rice Bay Formation. The the west on the paved road to Cape Santa Maria. overall setting here appears to be very similar to Follow this road to the T-intersection with the that of Sandy Hook, the Holocene strand plain Cape Santa Maria main road and tum left. on San Salvador (Camey et al., 1996), and to the Continue south on the Cape Santa Maria road for Holocene beach-dune complex of the Joulters about 1.25 km; a sign "Beach Reserve" on the Cays off the north end of North Andros Island right side marks the Stella Maris property. Tum (Boardman and Camey, 2000). Camey et al. right on the sand road heading toward the beach (1996) determined that the strand plain on San and park. Salvador developed by shoreline progradation of Cape Santa Maria is a spit-like feature a beach-dune complex over the past few that has developed in later Holocene time with thousand years. The main elements of their rising sea level. The beaches of the Cape are model of strand plain formationvery likely could among the most beautifulfound anywhere in The be applied to Cape Santa Maria, although no Bahamas, and the shallow waters normally are as detailed study of this area has yet been clear and delightful as seawater can be. undertaken. Excellent ripple patternsand other shallow-water Bedding within the low fossil dunes is bedforms lie offshore. Unfortunately, we will well displayed in many areas, particularly on the not have time today fora snorkel swim. lee slopes of the dunes. Modem snail shells and An extensive field of low, variably land crab parts are abundant; note that the · lithified fossil dunes lies on either side of the Cerion shells present here are smaller than those sand access road and extends to the west across seen at the earlier stops on the east side of Long the Cape Santa Maria main road. From the bus, Island, attesting to the morphologic plasticity of walk to the north and stroll amongst the low this remarkable land snail. The vegetation, while dunes (Fig. 32). Notice that no paleosol is not thick, is that of a Bahamian coastal coppice. present, indicating that these dunes are Holocene Small palm trees are common in this area, and in age. As one moves west toward the beach, the their trunks have diameters comparable to those dunes begin to level out a bit. On the backside of the vertical, cylindrical holes preserved in the of the beach, lithified horizontal beds are Holocene dune beds seen at Stops 1 and 3. present, representing a beach backshore Move from thefossil dunes over to the environment with deposition near or at present modem beach, and walk a short distance to the 19 -·-�:'.A··· "\ . c,,,,, .. � ";J. . . t7,._. - . ,,,,..--·'i . - . \ . . 'l; '".-l"��:_"irL: Figure 33. Holocene Hanna Bay Member backshore beds cropping out along the Santa Maria beach. Photo by Al Curran. north toward the rock outcrops (Figure 33). If CONCLUDINGREMARKS the tide is low enough, a good vertical-surface view of these exposures will be possible. The The purpose of this field trip to Long horizontal beds represent deposition in a beach Island has been to present to participants uppermost foreshore to backshore setting, very attending the 12th Geology Symposium an much like that described for similar beds of the introduction to Bahamian geology and an Hanna Bay Member on Lee Stocking Island overview of some of the more important and (White and Curran, 1993) and San Salvador interesting geologic features of the north end of (Curran and White, 1987, 1999, 2001). Beds Long Island. The stops selected and their order with well-developed bubble porosity are of presentation were arranged to provide common. Specimens of the trace fossil efficiency of transportation, to meet permission Psilonichnus upsilon, constructed by the ghost requirements, and to exhibit the best snapshot crab Ocypode quadrata, are moderately common possible of the available geology. We hope that and indicative of a backshore environment the geology of the field stops visited today will (Curran and White 1987, 1991). The overlying generate lively and productive discussion beds display low dip angles and represent throughout the time of this Symposium and transition to a dunal environment. Trace fossils beyond. The field trip leaders welcome your formed by insects occur in these beds, notably comments and criticisms. Please share your specimens of the stellate burrow (Fig. 34), thoughts with us during the Symposium. interpreted by Curran and White (1999, 2001) to have been formed by sweat bees. Some small ACKNOWLDEGMENTS cluster burrows, similar to those described by Curran and White (1999, 2001), also occur in The field trip leaders are grateful to the these rocks, along with numerous root molds and staffof the Stella Maris Resort and its managers, some rhizomorphs. Joerg Friese, Peter Kuska, and Jill Smith, for full This stop ends our field trip on Long logistical support and entry permissions for this Island. Return to the bus and re-board. We will field trip. Over its several decades of existence, retrace our route to the main road and head south The Gerace Research Center (formerly the to the airport. After a brief stop to use the Bahamian Field Station) has been instrumental facilities, we will board theplanes and flyto San in support of geological investigations Salvador Island for the start of the 12th Geology throughout the Bahamas and of much of the Symposium. research presented herein. The staff of the 20 Gerace Research Center also provided full Geology of the Bahamas: San Salvador, background logistical support for the field trip. Bahamian Field Station, p. 73-81. Jim Carew, College of Charleston, extended valuable consultation to the planning efforts for Carew, J. L., and Mylroie, J. E., 1989b, Stratigrtaphy, this field trip, and Tony Caldanaro, Smith depositional history, and karst of San College, provided technical assistance with the Salvador Island, Bahamas, in Curran, H. A., ed., Pleistocene and Holocene carbonate production of the guidebook. As always, the environments on San Salvador Island, people of Long Island and The Bahamas have Bahamas - Field trip guidebook Tl 75, 28th been most gracious and helpful in assisting us in International Geological Congress, American our field investigations. They have provided Geophysical Union, Washington, D.C., p. 7- transportation, guided us to outcrops and caves, 15. assisted with our surveys, granted permissions for access to private lands, and generally made Carew, J. L., and Mylroie, J.E., 1991, A stratigraphic us feelwelcome. We extend our thanks to all. model of the Bahama Islands: Geological Society of America Abstractswith Programs, REFERENCES CITED v. 23, no. 1, p. 14. Boardman, M. 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E., 1985, Pleistocene and Holocene stratigraphy of San Salvador Carew, J. L., and Mylroie, J.E., 1997, Geology of the Island, Bahamas, with reference to marine Bahamas, in Vacher, H. L., and Quinn, T. M., eds., Geology and Hydrogeology of and terrestrial lithofacies at French Bay, in Curran, H. A., ed., Guidebook forGeological Carbonate Islands: Amsterdam, Elsevier Society of America, Orlando Annual Science Publishers, p. 91-139. Meeting Field Trip #2: San Salvador, CCFL Bahamian Field Station, p. 11-61. Carew, J. L., and Mylroie, J. E., 2001, Quaternary I Carbonate Eolianites of the Bahamas: Useful Carew, J. L., and Mylroie, J. E., 1987, A refined analogues for the interpretation of ancient rocks?, Abegg, F. E., Harris, P. M., and geochronology for San Salvador Island ' in Bahamas, in Curran, H. A., ed., Proceedings Loope, D. B., eds., Modem and Ancient of the Third Symposium on the Geology of Carbonate Eolianites: Sedimentology, the Bahamas: Ft. Lauderdale, Florida, CCFL Sequence Stratigraphy, and Diagenesis: Bahamian Field Station, p. 35-44. Tulsa, SE PM (Society for Sedimentary Geology) Special Publication No. 71, p. 33- Carew, J. L., and Mylroie, J.E., 1989a, The geology 45. of eastern South Andros Island, Bahamas: A preliminary report, in Mylroie, J. E., ed., Carney, C., and Boardman, M. R., 1991, Oolitic Proceedings of the Fourth Symposium on the sediments in a moderncarbonate lagoon, 21 Graham's Harbor, San Salvador, Bahamas: Curran, H. A., and White, B., 2001, Ichnology of Geological Society of America Abstracts Holocene carbonate eolianites of the with Programs, v. 23, no. 5, p. A225. Bahamas, in Abegg, F. E.,Harris, P. M., and Loope, D. B., eds., Modem and Ancient Camey, C., Stoyka, G. S., Boardman, M. 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W., and Pray, L. C., 1970, Geologic Garrett, P., and Gould, S. J., 1984, Geology of New nomenclature and classification of porosity Providence Island, Bahamas: Geological in sedimentary carbonates: American Society of America Bulletin, v. 95, p. 209- Association of Petroleum Geologists 220. Bulletin, v. 54, p. 207-250. Goodfriend, G. A., Gould, S. J., andHarasewych, M. Curran, H. A., and White, B., 1987, Trace fossils in G., 2002, The Holocene fossil record of carbonate upper beach rocks and eolianites; Cerion land snails in eolian sands along the recognition of the backshore to dune east coast of Long Island, Bahamas: transition, in Curran,H. A., ed., Proceedings Abstracts and Program, The Eleventh of the Third Symposium on the Geology of Symposium on the Geology of the Bahamas the Bahamas: Ft. Lauderdale, CCFL and Other Carbonate Regions: San Salvador, Bahamian Field Station, p. 243-254. GeraceResearch Center, p. 15-16. Curran,H. A., and White, B., 1991, Trace fossils of Gould, S. 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E., eds., Proceedings of the Ninth Bahamas: Geological Society of America Symposium on the Geology of the Bahamas Abstractswith Programs, v. 23, no. 1, p. 40. and Other CarbonateRegions: San Salvador, Bahamian Field Station, p. 22-35. 22 Hearty, P.J. and Kindler, P., 1993, New perspectives Sedimentary Geology) Special Publication on Bahamian geology: San Salvador Island, No. 70, p. 17-39. Bahamas: Journal of Coastal Research, v. 9, p. 577-594. Melim, L.A., and Masaferro, J. L., 1997, Geology of the Bahamas: Subsurface geology of the Hearty, P.J., and Kindler, P., 1995, Sea-level Bahama Banks, in Vacher, H. L., and Quinn, highstand chronology from stable carbonate T. M., eds., Geology and Hydrogeology of platforms (Bermuda and the Bahamas): Carbonate Islands: Amsterdam, Elsevier Journal of Coastal Research, v. 11, p. 675- Science Publishers, p. 161-182. 689. Meyerhoff,A. A., andHatten, C. W., 1974, Bahamas Hutto, T., and Carew, J. L., 1984, Petrology of eolian salient of North America: Tectonic calcarenites, San Salvador Island, Bahamas, framework, stratigraphy, and petroleum in Teeter, J. W., ed., Proceedings of the potential: American Association of Second Symposium on the Geology of the Petroleum Geologists Bulletin, v. 58, p. Bahamas: San Salvador, CCFL Bahamian 1201-1239. Field Station, p. 197-207. Mirecki, J. E., Carew, J. L., and Mylroie, J. E., Kindler, P., 1995, New data on the Holocene 1993, Precision of amino acid enantio-meric stratigraphy of Lee Stocking Island data fromfossiliferous Late Quaternaryunits, (Bahamas) and its relation to sea-level San Salvador Island, Bahamas, in White, B., history: in Curran, H.A., and White, B., eds., ed., Proceedings of the Sixth Symposium Terrestrial and Shallow Marine Geology of on the Geology of the Bahamas, San the Bahamas and Bermuda: Boulder, Salvador, Bahamian Field Station, p. 95-101. Colorado, Geological Society of America Special Paper 300, p. 105-116. Mullins, H. T., and Lynts, G. W., 1977, Origin of the Northwestern Bahama Platform: Review and Kindler, P., and Hearty, P. J., 1996, Carbonate Reinterpretation: Geological Society of petrography as an indicator of climate and America Bulletin, v. 88, p. 1477-1461. sea-level changes: new data from Bahamian Quaternary units: Sedimentology, v. 43, p. Mullins, H. T., and Hine, A. C., 1989, Scalloped 381-399. bank margins: Beginning of the end for carbonate platforms?: Geology, v. 17, p. 30- Kindler, P., and Hearty, P. J., 1997, Geology of the 39. Bahamas: Architecture of Bahamian Islands, in Vacher, H. L., and Quinn, T. M., eds., Mullins, H. T., and Hine, A. C., 1990, Reply to Geology and Hydrogeology of Carbonate comments by M. M. Ball: Geology, v. 18, Islands: Amsterdam, Elsevier Science p.95-96. Publishers, p. 141-160. Mylroie, J. E., Carew, J. L., Sealey, N. E., and Ladd, J. W., and Sheridan, R. E., 1987, Seismic Mylroie, J. R., 1991, Cave development on stratigraphy of the Bahamas: American New Providence Island and Long Island, Association of Petroleum Geologists Bahamas: Cave Science, v. 18, p. 139-151. Bulletin, v. 71, p. 719-736. Mylroie, J. E., Carew, J. L., and Moore, A. I., 1995, Manfrino, C. M., and Ginsburg, R. N., 2001, Blue holes: Definition and genesis: Pliocene to Pleistocene Deposition History of Carbonates and Evaporites, v. 10, p. 225- the Upper Platform Margin, in Ginsburg, R. 233. N., ed., Subsurface Geology of a Prograding Carbonate Platform Margin, Great Bahama Panuska, B. C., Mylroie, J. E., and Carew, J. L., Bank: Results of the Bahamas Drilling 1999, Paleomagnetic evidence for three Project: Tulsa, SEPM (Society for Pleistocene paleosols on San Salvador Island, 23 in Curran, H. A., and Mylroie, J. E., eds., Vacher, H. L., and Mylroie, J. E., 2002, Eogenetic Proceedings of the Ninth Symposium on the karst from the perspective of an equivalent Geology of the Bahamas and Other porous medium: Carbonates and Evaporites, Carbonate Regions: San Salvador, Bahamian v. 17,no. 2,p. 182-196. Field Station, p. 93-100. White, B., and Curran, H. A., 1988, Mesoscale Panuska, B. C., Boardman, M. R., Carew, J. L., physical sedimentary structures and trace Mylroie, J. E., Sealey, N. E., and Voegeli, fossils in Holocene eolianites from San V., 2002, Eleuthera Island Field Trip Guide, Salvador, Bahamas: Sedimentary Geology, v. Eleventh Symposium on the Geology of the 55, p. 163-184. Bahamas and Other Carbonate Regions: San Salvador,Gerace Research Center, 20 p. White, B., and Curran, H. A., 1993, Sedimentology and ichnology of Holocene dune and Sheridan, R. E., Crosby, J. T., Bryan, G. M., and backshore deposits, Lee Stocking Island, Stoffa,P. L., 1981, Stratigraphy and structure Bahamas, in White, B., ed., Proceedings of of southern Blake Plateau, northern Florida the Sixth Symposium on the Geology of the Straits, and northern Bahama platform from Bahamas: San Salvador, Bahamian Field multichannel seismic reflection data: Station, p. 181-191. American Association of Petroleum Geologists Bulletin, v. 65,p. 2571-2593. Wilbur, R. J., 1987, Geology of Little San Salvador Island and West Plana Cay: Preliminary Taborosi, D., Jenson, J. W., and Mylroie, J. E., in findings and implications for Bahamian press, Karren features in island karst: Guam, island stratigraphy, in Curran, H. A., ed., Mariana Islands: Zeitschrift fur Proceedings of the Third Symposium on the Geomorphologie. Geology of the Bahamas: Fort Lauderdale, Florida, CCFL Bahamian Field Station, p. Titus, R., 1980, Emergent Facies Patterns on San 181-204. Salvador Island, Bahamas, in Gerace, D. T., ed., Field Guide to the Geology of San Wilbur, R. J., 1991, Morphostratigraphy and Salvador: Miami, CCFL Bahamian Field depositional facies of West Plana Cay and Station,p. 92-105. Little San Salvador, Bahamas: Carbonate island response to sea level change: Uchupi, E., Milliman, J. D., Luyendyk, B. P., Brown, Geological Society of America Abstracts C. 0., and Emery, K. 0., 1971, Structure and with Programs,v. 23, no. 1, p. 149. origin of the southeastern Bahamas: American Association of Petroleum Wilson, W. L., 1994, Morphology and Hydrology of Geologists Bulletin,v. 55,p. 687-704. the Deepest Known Cave in the Bahamas: Dean's Blue Hole, Long Island, in Boardman, Vacher, H. L., and Hearty, P., 1989, History of stage M. R., ed., Proceedings of the Seventh 5 sea level in Bermuda: Review with new Symposium on the Geology of the Bahamas: evidence of a brief rise to present sea level San Salvador, Bahamian Field Station, p. 21. during substage SA: Quaternary Science Reviews, v. 8,p. 159-168. Vacher, H. L. and Bengtsson, T. 0., 1989, Effect of hydraulic conductivity on the residence time of meteoric ground water in Bermudian- and Bahamian-type Islands, in Mylroie, J. E., ed., Proceedings of the Fourth Symposium on the Geology of the Bahamas: San Salvador, Bahamian Field Station, p. 337-351. 24 Notes , Columbus Monument (Stop8) \ NORTHERN PORTION OF LONGISLAND,BAHAMAS Cape Santa Maria (Stop 9) '----..... f� '-i-A'0 . 0 00 �1- HOG CAD . Stella Maris (Stops 1-6) I N A Millerton O 1 2 Kllom eters Locations of field trip stops described in this guidebook. Cartography by Doug Gamble. San Salvador, Bahamas (242) 331-2520 .phoµe (242) 331-2524 fax Gerace Research Center U.S. Mailing Address c/o 1\vinAir, Suite 113 1100 Lee Wagener Boulevard Fort Lauderdale, Florida 33315 For the study of Archaeology, Biology, Geology, and Marine Science