December 2004 Cainozoic Research, 3(1-2), pp. 189-219, In: Donovan, S.K. (ed.). The Mid-Cainozoic WhiteLimestone Group ofJamaica

Karst geomorphology of the White Limestone Group

David+J. Miller

DepartmentofGeography and Geology, University ofthe West Indies, Mona, Kingston 7, Jamaica; e-mail: [email protected]

Received 22 July 2002; revised version accepted 27 May 2003

The karst geomorphologyofthe WhiteLimestone Group of Jamaica is reviewed. The lithological and structural characteristics ofthe

White Limestone Group are examined in relation to its karstification, specifically material properties such as purity, petrology, porosity

and mechanical strength, which have been regarded as important in the development ofkarst landforms. The structural setting and

palaeogeography during the deposition of the WhiteLimestone, togetherwith subsequentblock faulting, are considered in relation

The of is examined the dissolution to the origin and evolution ofthe karst topography. phenomenon case-hardening as are processes

and influences related the of soil The karst features the White Limestone considered to presence a cover. on Group are in two

categories; small-scale dissolution sculpturing phenomena,collectively termed karren, and larger scale landforms. The latter can be

further divided into karst landform assemblages comprising doline, cockpit and tower karst. Cockpit karst is the most common

landform unit on the White Limestone Group, and occurs on the harder crystalline limestones, dolostones and where case-hardening

is important. Tower karst occurs on similar lithologies, but has a more restricted distribution. Doline karst is largely restricted to the

chalky Montpelier Formation. The geomorphological characteristics of each landform type are described and their origin discussed.

Other karst landforms include poljes, ridge karst, glades and a range of fluviokarst, each ofwhich are described. The cave systems

and underground rivers are also considered. Karst morphometric studies and theories of landform evolution are reviewed.

KEY WORDS: White Limestone Group, Jamaica, karst terrain, geomorphology.

Introduction karstified than the underlying Yellow Limestone because

of its purity and as a result of the extensive development

The White Limestone Group is geographically the most of a secondary permeability along lines of structural

unit in Jamaica and directed dissolution of the widespread lithostratigraphic crops weakness, leading to

of the island. Much of the is limestones. Dissolution of the limestones lines of out over 60-65% outcrop along

of karst landformsacross the weakness has formed a classic karst karstified, forming a range landscape. island (e.g., Sweeting, 1958; Versey, 1972). Indeed, The The palaeogeography and depositional setting of the

Cockpit Country (Figure 1) in northern Jamaica is famous White Limestone Group is examinedby Mitchell (2004)

worldwide for its spectacular karst topography, it being and is considered to represent a tectonically quiet phase in

the type area for a tropical limestone terraintermed cock- Jamaica’s geological history. Essentially, the carbonates

defined pit karst (kegelkarst). Cockpit karst is the most widespread were laid down on a block and belt structure by

landform type and occupies about 60% of all karst in two major fault systems, an east-west set and a northwest-

Jamaica (Day, 1979). It comprises steep-sided, enclosed southeast set (Draper, 1987). The rapid subsidence of the

with led of the Yellow Limestone depressions convex side-slopes, forming depressions troughs to deposition Group

in Other in the Middle the chalks of the which are star-shaped or polygonal plan. com- and, Eocene, deep-water

mon karst landform assemblages are dolinekarst, where White Limestones, while eventual subsidence and sub-

the landscape is dominated by oval- or circular-shaped mergence of the blocks initiated shallow-water pure-

depressions; tower karst, forming isolated residual hills carbonate sedimentation.The karstification of the White

in the when renewed rising above an alluvial plain, planed limestone or non- Limestone Group began Miocene

karstic which deformation the limestones. Surface erosion and rocks; and poljes, are large, structurally uplifted

controlleddepressions surroundedby a steep rim of lime- continued incision de-roofed the siliciclastics of the Yel-

stone or, at least in part, non-carbonate rocks. There is low Limestones and the older Cretaceous rocks, to form a

also a wide range of fluviokarst features associated with series ofinliers, producing surface streams which provided

the White Limestones. large volumes of water to the White Limestones via river

The White Limestone Group is more extensively sinks and which greatly modifiedthe karst from an essen- - 190-

1 = 2 = = 4 = 5 Figure 1. Locality map. Key: Cockpit Country; Natural Bridge, Riversdale; 3 Central Inlier; John Crow Mountains;

======Hellshire Hills; 6 Kemps Hill; 7 = Brown’s Town; 8 Moneague; 9 PortlandRidge; 10 South Manchesterplateau; 11

CabaritaRiver; 12 =Nain; 13a = Lower Black River Morass; 13b =Upper Black River Morass; 14 = Burnt Savannah; 15 = Santa

Cruz; 16 =Top Hill; 17 = Ballards Valley; 18 = Bull Savannah; 19 = Barbecue Bottom; 20 = Lluidas Vale; 21 =Queen of Spain’s

Valley; 22 = DuanvaleFault Zone; 23 =Roaring River; 24 = Martha Brae River; 25 =Dallas Mountain; 26 = Long Mountain;27

=Brazilletto Mountains; 28 = Round Hill; 29 = Great Goat Island; 30 = Savannah La Mar; 31 = Little London; 32 = Discovery

= = Bay; 33 = St Ann’s Bay; 34 = Quashies River Cave; 35 = Domock Head; 36 = Bristol Cave; 37 Dry Harbour Mountains; 38

Windsor; 39= Troy.

2. General of north-central the main karst landform on Figure geomorphologicalmap Jamaica, showing assemblages (based Sweeting,

1958). - 191 -

to mixed karst In the tially autogenic a allogenic-autogenic (1958). 1960s, a number of German geomorpholo-

on the northern side of the island. Pfeffer system, particularly gists, notably (1967, 1969), also worked on the

Karstification ofthe limestoneshas continued through the karst of the WhiteLimestones, specifically in the northof later Tertiary and into the Quaternary. the island and across southern St Elizabeth.

Versey (1972) also reviewed the karst geomorphology

of the island from a geological perspective. Gardner et al.

Historical review (1987) published a summary of Jamaican karst, chiefly

from the earlier reviews of Sweeting and Versey, and a

Some of the earliest descriptions of the karst in Jamaica more review recent summary was presented by Draper &

were related to cave summarised in Fincham early explorations, (1997). Other investigations are related to karst Fincham The earliest of in (1997). descriptions caves landform evolution (e g., Landmann, 1990; Pfeffer, 1986, detail those Edward who were by Long (1774), published 1997) and to karst landform development ( Smith et e.g., a three-volume history of Jamaica, which contains de- al. 1972). , of three In his remarks the of scriptions caves. on geology Karst morphometric studies on the WhiteLimestones la Beche Jamaica, De (1827) described the Natural Bridge have, to date, been restricted to relatively small, localised

at Riversdale, which was the first surface feature to of karst areas Jamaica. These studies include the work of Day be documented (Miller & Donovan, 1999). Sawkins (1976, 1978a) and Brook & Hanson (1986, 1991). detailed of (1869) provided a account the geology and

of the island. The hydrology Cockpit Country was men-

tioned in this volume for the first time, where the cockpits, Geological background

dolines and lightholes were described and attributed to

collapse of the limestones into Some The karst of Jamaica pre-existing caverns. provides a good example of both

thirty after the of the a reas- and structural controls years publication memoir, lithological on its development

sessment ofthe geology of Jamaica was produced by Hill et while the (Gardner al., 1987), case-hardening of many

(1899) and, although there was little considerationof the of the White Limestones has also had a significance

he attributed the of the karst, origin cockpits to solution, influence on the development of karst landforms.

not few collapse. A years later, Dane (1909, 1914) de-

scribed the and other karst cockpits features, and also Lithological and materialproperties

favoured solution, predominantly along joints and fissures,

for the formation of the His contribu- There is control karst landform cockpits. principal a strong on development

tion to the of karst studies add development was to de- related to lithology and specifically to certain material tailed observations of karst in Jamaica tropical to Euro- properties of the limestones. Sweeting (1958) noted that investigations which had hitherto been the pean basis for vertical relief development in the form of both cockpit and

karst evolution theories Lehmann karst is confined the (Fincham, 1997). tower to areas of hard crystalline (1954) examined the karst in northern Jamaica and also White Limestone, as well as to areas of high rainfall solutional suggested a to the of cock- totals. In where the Limestone is origin development areas White more marly, pits. where or the rainfall amounts are relatively low, the

In 1955, Marjorie Sweeting, a karst geomorphologist landscape is dominated by doline karst. Sweeting further

from the of conducted two-month indicated University Oxford, a a link between lateral relief development and

of studies in Jamaica in associa- programme hydrological lithology, as poljes are normally associated with the marly

tion with the Division. These studies which Geological Survey limestones, promote extensive flooding and lateral led three the to publications on hydrogeology and karst planation. Urquhart (1958) also indicated that ‘cockpit

geomorphology ofthe limestonesof the island, but karst’ is the hard specifi- developed on pure, and fissile

the White Limestone areas while ‘doline karst’ is cally (Sweeting, 1956, 1957, limestones, present on those which Her 1958 become the seminal 1958). publication was to are marly or impure. White & Dunn (1962) also suggested

work on the karstlands of Jamaica, and the first major the solubility, massiveness and well-developed joints of review of the limestone geomorphology and hydrology of the White Limestone have been major factors in the the island, including the first general karst geomor- development of karst topography in Jamaica. of the northern of phological map part Jamaica (Figure 2). Versey (1972) suggested that, in terms of the impor- This stimulated wider interest in Jamaican karst a and tance of lithological properties to karst hydrology, three established The broad Cockpit Country as a geomorphological lithological divisions can be identified, each with

tropical terrain-type. She published later reviews and differing hydrological The first the regimes. group are of Jamaican karst in her 1972 Karst chalks descriptions book, Montpelier which, according to Versey, are char-

where she also documented acterised rather Landforms, previously unpub- by a primary, than diagenetic, porosity. lished work other authors, by notably Conrad Aub. Other This, together with the paucity of fractures, leads to a

general descriptions of the karst of the island were pub- well-developed primary permeability, such that ground- lished in the 1950s Doerr & and by Hoy (1957) Urquhart water movements occur through the body of the rock - 192-

rather than via conduits (Versey, 1972; Gardner et al., The White Limestone Group formations are, for the

rock based carbonates. noted 1987). Versey’s second division on hydrologi- most part, extremely pure Versey (1972)

cal characteristics is the recrystallized limestones and that the non-carbonate fraction seldom exceeds 2% and is

dolostones, representing the oldest formations withinthe generally less than 0.5%. Comer (1974) (Table 1) found

Middle White Limestone White Limestone Group. These rocks are characterised by the Eocene to Lower Miocene

no primary permeability and groundwater movements are Group to be on average 99.87 % pure calcium carbonate

of flow and that the of the insoluble residue could have entirely along fissures. Definite lines groundwater source

have developed only along the largest fractures (Gardner been contaminationof the samples by bauxite or terra rosa

et al., 1987). Enlargement of joints and other lines of soil. Comer also examined the Middle and Upper Miocene

weakness is the result of directed dissolution and the carbonates ofthe Montpelier Formation (Table 2), which

development of secondary permeability. Versey (1972) contain several thin bentonitic interbeds and disseminated

characterisedthe rest ofthe White Limestone Group as a clays. These limestones were foundto contain on average

‘rubbly limestone’, having a widespread nodular texture, 6.17% insoluble residue, chiefly oxides of Si, A1 and Fe,

with occasional hard bands. The variable lithologies in the form of bentonitic and montmorilloniteclays.

results of acetic acid insoluble within Versey’s ‘rubbly limestones’ range from soft Day (1976) reported the

lime- residue limestones which indicate that powdery textures which are nearly impermeable, to experiments on the

the Walderston referred the stone conglomerates which are highly permeable. Browns Town, (both now to

0/ /o % % % % % % %

Insoluble Fe Si0 ai o P Ti0 CaO co 2Oj 2 2 3 2Os 2 2

Residue

0.1275 0.0017 0.0275 0.0060 0.2072 0.0005 55.94 43.93

Table 1. Summary chemical composition of Middle Eocene to Lower Miocenelimestones of Jamaica(from Comer,

1974).

% % % % % % % %

Fe 0 CaO Insoluble 2 3 SiOz AhO, PzO s TiOz COz

Residue

6.1715 0.47 3.179 0.975 0.069 0.0048 52.69 41.28

Table 2. Summary chemical composition ofMiddle and Upper Miocene limestones of Jamaica (from Comer, 1974).

O/ O/ O/ /o /o /o Schmidt

Formation Insoluble Dominant Texture Sparry Estimated Hammer

Residue Specification Calcite Porosity Hardness

Content Test

Montpelier 0.23 Fossiliferous Fine <10 <5 32.6

Micrite

Bonnygate - Foraminiferal Fine <10 <10 30.4

(herein, Montpelier) Micrite

Walderston 0.16 Biomicrite Fine-Medium 20-30 10-15 29.7

(herein, Moneague)

Brown’s Town 0.12 Biomicrite Fine-Medium 30-40 10-15 32.1

(herein,Moneague)

Somerset 0.08 Biosparite Medium 40-50 <10 33.1

Swanswick 0.09 Biosparite Fine-Medium 30-40 10-15 36.3

Claremont 0.03 - - “

(herein, Troy)

Troy Dolomitic Medium 10 <10 42.3

Limestone

Table 3. Summary material properties of formations ofthe White Limestone Group of Jamaica (from Day, 1976, 1979, 1982). - 193 -

Somerset Moneague Formation; Mitchell, 2004), and suiting geological structures have imparted significant Claremont of the formations (now part Troy Formation) control on the development of karst landforms within the

all contain less than cent considerably one per by weight White Limestone Group, not least, the block faulting and

insoluble residue further examined extensive fault (Table 3). Day (1982) east-west trending systems, the anticlinal the role of material properties in the development of karst folding of the platform carbonates and the erosional

terrain in a number of localities within the Caribbeanand breaching of this structure, together with subsequent de- central the America, on basis of the purity, petrography roofing to form the Central Inlier. A detailed discussion of

and mechanical of the hardness limestones in relationto the structural geology and tectonic evolution of Jamaica is

the karst landform type developed He also the (Table 3). beyond scope of this paper and the reader is directed described the White Limestone as extremely pure; of the to recent reviews ofthe block and belt structures by Draper the Somerset Formation samples tested, was foundto be (1987, 1998), Lewis & Draper (1990) and Robinson

the most with 0.08% insoluble residue. pure, only Day (1994). Essentially, Jamaica consists of threemain struc-

examined the nature of the limestones petrographic and tural blocks, separated by two northwest-trending graben the he samples are biomicrites or micrites The analysed mostly structures (e.g., Draper, 1998). blocks are composed

(Table 3), with a low of of relatively percentage sparry Cretaceous volcanics, siliciclastic sedimentary rocks calcite, though his samples of Swanswick and Somerset with minor limestones, and granitoid intrusive rocks, limestones classified The For- were as biosparites. Troy capped by Tertiary limestones, and comprise, from east to

mation was classified dolomitic as a limestone and dis- west, the Blue Mountain Block, the Clarendon Block and

played extensive recrystallisation. the rocks the Texturally Hanover Block (Draper, 1998; Robinson, 1994). The

were found to be fine- to which is belts medium-grained, re- separating the blocks are faultbounded and Tertiary flected in the low estimated of porosities <15%. Day also in age. They consist of the Wagwater belt of siliciclastic

a of results obtained from in situ the provided summary sedimentary rocks, Montpelier-Newmarket belt com- Schmidt Hammer and found the White Limestones testing prising Tertiary limestones and the North Coast belt, from hard the vary moderately to very hard, with dolomi- which abuts the northernmargin ofthe Clarendon Block tic limestone of the Formation the Troy being hardest, and consists of deeper water limestones.

limestone recrystallisation having destroyed the original The Lower Cretaceous to Palaeogene rocks, exposed in

texture and resulted in increased cementation several of island strength. inliers, represent parts an arc system correlate Day (1982) attempted to purity, petrographic (Draper, 1998). In the Palaeocene Jamaica rifted along characteristics and mechanical with terrain strength type, major northwest-southeast-trending faults, when the

and found that the most striking correlation is between block and of the island present graben structure was terrain and hardness type of the rock types as demon- formed (Draper, 1998) producing blocks of different

strated the Schmidt where ‘tower karst’ tends After by Hammer, height. cessation of the arc system, from the late

to on the hardest and ‘doline develop rocks, karst’ on the Early Eocene to the Late Miocene, differential subsidence softest. concludedthat the role Day of lithological varia- occurred and transgression led to the accumulation of

and of mechani- shallow carbonate tion, particularly hardness, as a measure water sediments on the main structural

cal is of attention. The strength deserving greater correla- blocks, although the Montpelier-Newmarket and North

tion between and terrain less Coast underwent purity, petrography type was belts greater subsidence, allowing for for the White Limestone but striking samples, this is due deeper water carbonate sedimentation (Draper, 1998). As to the fact thatall and are extremely pure mostly micritic, well as controlling the lithology of the limestones, the and is also reflection of the small size. a sample More tectonic activity uplifted and exposed the island during the recently, Pfeffer indicated that however, (1986) cockpit later Cainozoic. The uplift from the Late Miocene is most karst occurs only on the limestones and that the ‘pure’ likely the result of northeast-southwest shortening which

cockpit hills are on the limestones. steeper purest accompanied east-west, left-lateral transcurrent motions, Limestones with marl tend form resid- which layers to less steep can be seen as three large, east-west trending fault ual hills and dolines, while the limestones that impure support systems cut through the island (Lewis & Draper, dolinekarst only. 1990; Draper, 1998). In terms of the structural influence The low of the relatively porosity limestones is impor- on karst topography, the Duanvale and the South Coast

as directed, rather than dissolution tant, diffuse, occurs fault systems are the most important, and the Plantain lines of along weakness to a Garden-Rio Minho is less develop secondary perme- system so. ability along joints and fissures, leading to the develop- On the Clarendon the Block, structural response to the ment of karst terrain through enhancedrates of dissolution northeast shortening accompanying the transcurrent where are tectonics the joints more common. was large scale anticlinal folding of the

carbonates form platform (Draper, 1998) to a major

westnorthwest-eastsoutheast-trending anticline. The tilting

Geological structure of the limbs of the anticline also provided the hydraulic

for much of the horizontal gradient necessary cave devel-

The overall tectonic evolution of the island and the in the re- opment centre of the island (Draper, 1998). Devel- - 194-

of the anticline followed south- flow direction and tend opment was by a general parallel to they to impart a strong ward tilting of the block. The erosional breaching of the control, acting as lines of preferential groundwater move- anticline and subsequent de-roofing, to expose the Creta- ment (Versey, 1972). The Miocene to recent tectonic ceous rocks of the Central Inlier, began about 9 Myr ago activity also produced many faults, which form numerous

lineaments satellite and in the Late Miocene (Draper, 1998). According to Draper, scarps, seen as strong on imagery

at the margins of the Clarendon Block, the early Tertiary aerial photographs (Draper, 1998).

reactivated landforms in the White Lime- northwest-southeast-trending faults were as The origin ofthe karst thrust faults. stone Group are closely related to the characterand atti-

In the east of the island, most of the northeast short- tude of the limestones and their tectonic evolution (Ver-

accommodated Gardner et ah, One of the main controls ening has been by thrusting along a sey, 1972; 1987).

northwest-southeast directed axis in the Wagwater and on the overall physiography of the limestones is their

Yallahs fault systems, which resulted in spectacular uplift block-faulted structure. This episode of block faulting

(Draper, 1998). This has resulted in the erosion of the occurred in the late Tertiary, and is more pronounced and

the north. the overlying White Limestone and the only remnants are the younger in the south than it is in Basically,

northeast dipping beds of the John Crow Mountains karst features are superimposed on the block-faulted

and (Draper, 1998). These limestones form a pronounced structural elements. According to Versey (1972)

Grande Gardner al. karst erosional have escarpment on the eastern slopes of the upper Rio et (1987), processes

other situa- Valley. accentuated the structures in some areas. In

the tions much of the has been masked The renewed uplift in the Miocene exposed car- original structure by

the blocks karstification and of in the interior bonate platforms on to ero- deposition alluvium, particularly valleys

and which have been rather sion. As far as the karst is concerned, the most important poljes, structurally depressed,

block is the Clarendon Block where two series of faults than being the result of erosion.

each have the has strong topographic expression (Versey, 1972). Hydrologically, faulting generated drainage

The east-west faults occur at the northern margin of the barriers and created distinct catchments within the karst.

block and especially form the Duanvale fault system, Someof the streams have eroded to base level and this has

which exerts strong geomorphological and hydrological resulted in a major modificationof earlier flow which was

Gardner controls on karst development. Similar east-west trending entirely subterranean(Versey, 1972; et ah, 1987).

faults to the south ofthe block, near to the coast, also have A major event was the erosional breaching and subsequent

anticlinal which is a profound effect on karst landforms. Across the Claren- de-roofing of the structure now exposed

in the Central which altered the don Block, the faults are more or less perpendicular to Inlier, fundamentally

ofthe karst the Clarendon Block. those along its margins, and trend between northeast- hydrological regime on

southwest and northwest-southeast. Most of the major Surface drainage from the Cretaceous rocks was directed

faults have clear topographic expression across the White onto and beneath the karst plateaus surrounding them.

the north of the karst modified from Limestones. According to Versey (1972), to Therefore, was an essentially

the Clarendon Block, in the North Coast belt, faulting autogenic system, where karstification was dominatedby

in the water carbonates of the diffuse vertical of gives way to folding deeper autogenic recharge by percolation

Montpelier chalks, which display clear dips, and faults rainwater through the limestones, to a mixed autogenic-

lose their clear topographic expression. The general allogenic system, whereadditional large volumes ofwater

absence of faults in the Montpelier Formation leads to low passed through the limestones as concentrated allogenic

from the Cental Inlier. secondary permeability, which in effect acts as a barrier to recharge, especially Versey (1972)

the northerly groundwater flow. It is also possible that suggested that the sediments contained within this allo-

would abraded the limestonesbefore impedance of drainage is caused by a reversal ofthe dip or genic water also have

by the upfaulting of the karst base (Gardner et ah, 1987). being deposited in interior valleys or carried to the sea.

The other facies of the White Limestones rarely display At the more detailed scale, Wadge & Draper (1977a,

clear dips and when they do the angle of inclination is b) investigated the tectonic control on cave development

generally small (15°), steeper dips indicating nearby in the limestones.Brook & Hanson (1991), in a quantita-

of and doline karst Brown’s faulting (Versey, 1972). The faulting had the effect of tive analysis cockpit near

generally increasing the permeability of the limestones, Town, parish of St Ann, showed that northwest- and

fractures influence though where the limestones were ‘initially so incoherent’, northeast-trending exert a major on

the evidenced the in the terrains and that the faulting decreases permeability as by topographic development cockpit

occurrence of fault-lineridges which have resisted disso- east-west-trending fractures are relatively more important

in the doline lution (Versey, 1972). areas.

Within the fault blocks of the Clarendon Block, the

north-south trending faults are roughly perpendicular to

groundwater flow and do not affect it significantly. How- Case hardening

ever, where the regional groundwater flow is north or

south through the limestones, the north-south faults are Calcareous weathering crusts commonly occur on residual - 195-

limestone hills and in outcrops tropical environments. A 2 m thick has been caprock observed on some quarry

Their significance for karst was first in the faces appreciated in Moneague Formation tower karst at Kemps Hill, Caribbean where the is known region, phenomena as case southern Clarendon, but more work needs to be done on

& Most of the work hardening (Ford Williams, 1989). on the importance of case hardening in karst development in in the Caribbean case hardening comes from Puerto Rico Jamaica.

(Monroe, 1966, 1968; Ireland, 1979) and Cuba (Panos &

Stelcl, 1968). Both Monroe (1966) and Sweeting (1972)

interpreted the hard caprock to be due to Dissolution secondary depo- processes andcontrols sition of calcium carbonate resulting from evaporation

soon after torrentialrain showers dissolve small amounts No systematic work has been done on dissolution proc- of limestone. Monroe considered (1966) case hardened esses and controls on limestone dissolution in Jamaica.

surfaces to be thicker windward due Two of controls limestone on exposed slopes, to groups on weathering can be

more pronounced wetting and though Ireland these drying, generally identified, being environmentaland geo-

indicatedthat it is much with the controls. In of (1979) more uniform, logical terms lithology and structure, the

zone of induration closely following topography. Com- main controls have already been discussed and occur at a

in Puerto Rico is 1 2 monly, case hardening to m thick, variety of spatial scales. Environmental controls fall into but it may be at least 5 m in extent (Ireland, 1979). Ivano- four broad categories, related to soil conditions, hydrology,

vich & Ireland considered for limestones (1984) that, topography and climate. A major control on limestone of consisting more than 50% fossils, the dominant case weathering and dissolution in is the general presence or is hardening process precipitation into solution cavities. In absence of a soil cover and the nature of the soil, espe- rocks with less than 20% the main is it relates fossils, process cially as to acidity, soil carbon dioxide produc-

aggrading neomorphism, a recrystallisation process re- tion and content, and organic content. Sweeting (1958) in the increase sulting progressive of microspar. In both indicated that, under tropical rainforest conditions, it

the is caused carbon dioxide would be that soils processes, precipitation by expected would have a high production

degassing and it leads to a significant reduction in poros- and concentrationof carbon dioxide. Accordingly, disso- ity of the limestones. lution of the limestones would be rapid, which helps to

Although there has been no systematic work completed explain the intense development of karst landforms and

on case in it is Pfeffer also in for the of hardening Jamaica, common. may account, part, occurrence wide- (1969) reported three distinct variations of karst cockpit in spread terra rosa soils and bauxite deposits, which are

small in southwest Jamaica in relation the one area to commonly associated with the White Limestone (Zans, of surface presence crusts. One type of conical hill is 1951a; Sweeting, 1958).

completely formed in firm a second is limestone, type Measurements of the levels of soil carbon dioxide were encrusted with external stalactites and travertine made the covering by University of Bristol Karst Hydrology Expe- the rock and while surface on overhangs, a third type is dition to Jamaica in 1967 (Smith, 1968, 1969a) and covered with residuals weathering and a limestone crust reported by Nicholson & Nicholson(1969). Carbon diox-

limestone The limestone ide in limestone overlying decomposed particles. levels soils over varied from 0.6 to 1.9%

travertine and stalactites crusts, reported by Pfeffer (1969) with the highest concentrations occurring in soils under

were taken to calcium natural woodland represent reprecipitated carbonate, with a high clay and humus content

which at least in forms case-hardened & part a caprock on (Nicholson Nicholson, 1969). It was found that the

some of the residual hills. On a smaller McFarlane lowest concentrations scale, occur under bare, cultivated soil the of (1980) reported occurrence razor-sharp, case- with low humus content in the surface horizon, but the hardenedkarren features the karst landforms of the on carbon dioxide content was generally higher than for soils

Formation referred to the For- in result of the Newport (now Moneague temperate regions as a greater levels of in the Hellshire Hills mation; Mitchell, 2004) (Figure 1). biological activity in higher temperatures (Nicholson & As indicated Ford & Williams by (1989), case hardening Nicholson, 1969). Day (1976) analysed the soil carbon is in especially important the development of karst on dioxide content in slightly to moderately acidic, red-brown weak and porous, mechanically diagenetically young bauxitic loams associated with doline-type depressions in

where it the rock more resistance limestones, gives to the Brown’s Town area and also found that levels were

erosion, and reduces its and than those associated porosity permeability. generally higher with temperate The case-hardening effect is normal the throughout conditions. Soil carbon dioxide content was higher when

WhiteLimestone but it is noticeable the soil Group, especially on was approaching saturation (Day, 1976). This

those units, such as the which wouldbe Moneague Formation, are due to the factthat soil carbon dioxide diffusion

micrites when soft, chalky to granular fresh. Thus, it to the surface is considerably reduced with increasing soil would that be seem case hardening may more important in moisture content. Day (1976) also found that carbon the development of karst on the and topography rubbly dioxide levels increased in the base of the depressions and limestone chalky formations, rather than the older recrys- with increasing depth, though he concluded that the tallised of which have been dolomitised. limestones, some importance ofa soil cover in facilitating limestone disso- - 196-

in Jamaica vial and natural The formation lution, as it relates to carbon dioxide content, fans, steepheads bridges. requires further investigation. and development of the surface karst phenomena is closely

in the ofthe White Limestone Trudgill (1977) investigated the role of a soil cover associated with hydrogeology

and and rivers limestone weathering in a small study in the Troy area on Group, cave systems underground are the southern boundary of Cockpit Country. Rates of important karst phenomena across the island. Karst

obtained lime- and the of work the weathering were by placing pre-weighed speleogenesis history speleological on stone tablets withinboth red and organic soils, which are island is summarised in Fincham (1997); herein, research

rivers is reviewed moderately acidic and with low carbonate content, and at on the cave systems and underground as the soil to bedrock interface. Soil carbon dioxide content it relates to the development of the karst as a whole. was also measured at the two White Limestone localities Localities referred to in the text appear in Figure 1. and was found to be lower in the organic soils, especially at the soil-rock interface, resulting fromrapid diffusion to the surface in the open leaf litter organic soil compared to Dissolution sculpturing

Measured the more compact mineral soil (Trudgill, 1977).

where work has been undertaken the erosion rates under both soil types were greater than No systematic on small-

related and scale solution of the limestones of the White soil cover was absent, and this is to leaching sculpturing the acid nature ofthe soils, rather than soil carbon dioxide Limestone Group. White & Dunn (1962) noted that the content (Trudgill, 1977). Trudgill also surmised that the major karst landforms are covered with extensive karren,

could affect the devel- and classified the solution hills and presence of a soil cover markedly sculpturing on cockpit

of dissected terrain the White of McFarlane opment on Limestone, as towers as a type spitzkarren. (1980) reported erosion rates would be greatest where pockets of red and a small descriptive study of karren morphology at three

soils to differentialrates of dissolu- localities withinthe White Limestone at organic occur, leading Group Troy (Troy tion. Formation), Portland Ridge and Hellshire Hills

Based on a considerationof effective runoff figures and (Moneague Formation). The features are predominantly of the valuesobtained for the hardness of springs resurging a linear nature in the Troy area, which contrasts markedly

sub-circular forms within the Portland from the White Limestones (Smith, 1969b), Smith et al. with the more

(1972) suggested that the overall erosion rate of the White Ridge and Hellshire Hills. It was further suggested that the

features in the better and Limestone area lies between 40 mm and 70 mm per 1,000 karren Troy area are developed

have wider of McFarlane years. According to Smith (1970), this variation is almost a range morphologies. (1980)

which differences be entirely due to spatial variation in effective runoff, postulated that the may dependant on

variation in rainfall factors. is controlled largely by amounts. climatological and, more particularly, lithological

More recently, Draper & Fincham (1997) noted the

of several of karren, solution presence types especially

Geomorphology pits, micro-pits and Hortonian runnels, which are wide-

spread on exposed surfaces on many different kinds of

The karst geomorphology ofthe WhiteLimestone Group limestone across the island. Other runnel or rill-like

can be examined at several spatial scales. On the small- features in the form of rinnenkarren and fluted scallops

there is of fine solution are also & Fincham, and scale, a range sculpturing present present (Draper 1997). Draper

limestones which is the of Fincham further indicated the occurrence of spitzkarren on many surfaces, product

dissolution of the limestones by slightly acidified rain- and cleft-like grikes on the thicker bedded and well- water, and subsequent surface vertical trickle and flow jointed limestones of the Troy/Claremont Formation,

under the influence of gravity. Collectively, these small- while honey-comb weathering features and littoral karren

scale features are referred to as karren and a wide variety forms occur on the White Limestone exposed near to the

coast. of such features are present, though to date very little

has been undertaken the The solution features iden- systematic work on phenomena. most common sculpturing

features is summarised tified the south the Work completed to date on karren on coast limestones, specifically

below. At the larger scale, there is a wide range of karst Moneague Formation, appear to be honey-comb weather-

features, from cockpit and dolinekarst, both largely the ing phenomena (Figure 3) and rain pits. Although spitz-

controlled linear product ofvertically-directed dissolution, and tower karst, karren is present, hydrodynamically

tend be less The author which is mainly related to laterally-directed dissolution, to sculpturing to common. agrees

the earlier observations of McFarlane that ridge karst and poljes, which have a strong structural with (1980)

control. Poljes also induce horizontal water movements at rillenkarren may be more prevalent on the older Troy

or near to the regional groundwater table. There is also a Formation, but more systematic work needs to be com-

of fluviokarst, and blind in this range including dry valleys, pleted regard. ephemeral limestone gullies and valleys with relict allu- - 197-

solution karst in the southern of Elizabeth. Figure 3. Honeycomb weathering onridge MoneagueFormation, parish St

Figure 4. Cockpit karst in northwest Cockpit Country, parish of Trelawny, showing well-developedpreferred orientations due to

faulting andjoint-patterns (photograph courtesy of Mr Jack Tyndale-Biscoe). - 198 -

Doline karst to contain semi- permanent ponds which fluctuate ac-

cording to supply of runoff.

is the the from the Doline karst an important landscape type on Mont- Day (1976) dye-traced water sinking pelier Formation and is also associated with areas of enclosed depressions to the dry and ephemeral valley

the Formation limestones relatively low annual rainfall (Sweeting, 1958). The systems traversing Montpelier

The marked largest area ofdoline karst on the White Limestone Group to the north of the study area. water com-

altitudes of 250 to 100 which occurs in the north central part of the island (Figure 2), a monly reappeared at m m,

inland from the where it vertical of flow inthe order of few kilometres coast, especially gives a height underground

150 Lateral distances of flow from 0.5 km is underlain by the relatively soft, chalky Montpelier m. ranged to limestone (Draper & Fincham, 1997). Sweeting (1958) 5.0 km and Day estimated travel times of between 0.25 km suggested that lithological and climatic conditions are to 0.5 km per day, which supports the idea that flow

of dolinekarst the rather than diffuse responsible for the development along occurs through conduits by percolation. north she did indicate that dolines in In the from the coast, though occur most cases, water sinking depressions the Moneague area, despite a fairly high annual rainfall. contributed to the flow in one valley only, but the main

According to Sweeting, the dolines on the Montpelier sources of flow to the valleys are not the depressions under

to the Formation are usually shallow and have an open v- or study, but the karstified limestones of the plateau

of funnel-shaped cross section. Similar shallow karst depres- south the study area (Day, 1976).

infer sions occur in the area around Brown’s Town, parish of St Day’s study indicatedthat it is not possible to the

dominant in the formationand devel- Ann in the north of the Dry Harbour Mountains (Day, process subsequent

and of enclosed He that small 1976). Day carried out a morphometric hydrological opment depressions. suggested

scale the initial which is study of the enclosed depressions for which he was careful collapse may provide form, not to use the term doline, though he asserted that, ‘Other subsequently modified by systematic solutional activity. workers might describe these simple depressions by the The enclosed depressions generally show a regular distri-

examined bution which could solutional term doline or sink’. The depressions by Day suggest activity, as collapse

extensive and and individual are laterally shallow, some events may produce a more random distribution pattern,

depressions occur within larger, more complex depres- while the control of structure on depression long axes sions, though their complexity cannot be distinguished by orientation could also be suggestive of solution, though size alone. The depressions range in diameter from <100 there is no reason why subsurface solution should not m to over 1 km, with a mean diameterof 219 m. Their result in preferred orientation of collapse features (Day,

depth range is also variable, with a mean depression depth 1976). In a laterpaper, Day (1984) attempted to predict of 18.4 m; although two of the largest depressions in the the location of surface collapse withinthese karst depres- area of study are >30 m deep, many of the depressions are sions.

Fincham indicate that doline karst relatively shallow. Day found that the depressions are Draper & (1997)

to the tilted in the southwest characterised by low angle slopes within a range of 2° also occurs on plateau areas part

of the island which underlain the 12°. The depression density was found to be 12.5 per km". are by relatively soft,

found correlation between and and weak Formation Day also a strong depth rubbly mechanically Newport (now

considered have devel- referred the diameter, which was unlikely to to Moneague Formation; Mitchell, 2004). is oped by chance and which must relate to the internal slope According to Draper and Fincham, the lithology too

development ofthe depressions. Many of the depressions weak to support the steeper and more pronounced residual

towards orientation in an hills associated with cockpit karst. Dolines and sinkholes, show a very strong tendency sub-circular in form and in di- east-west direction, with other weak orientations in an circular to plan varying approximately northwest-southeast direction.Day (1976) ameter from a few metres to over 1 km, are common

the south Manchester and westwards into interpreted the east-west direction as corresponding with across plateau

Duanvale fault which southern St. Elizabeth. There is wide of the eastward extension of the zone, a spectrum forms,

orientationof between 71° from hollows and crosses the study area with an ranging saucer-shaped to funnels, cones

and while of faults orientated and isolated 80°, a secondary group are cylindrical pits, they may occur as depres-

Within this between 310° and 320°. Stream channel networks within sions or pock-mark the terrain in clusters.

threefold subdivisionof dolinekarst be related the depressions were also analysed and the depressions area, a can

ranked in relation to the network order. This was com- to the characteristics of their associated positive relief

features. pared with depression size and it was found that depres-

with channel order. It The first dolinekarst is circular sion area increases increasing was category typified by to

which 2 sub-circular from 100 400 in found that the channels, are commonly up to m depressions, ranging m to m

and contain surface runoff times of but around 150 m to 250 deep 4 m wide, only at diameter, more commonly m,

conical to to 30 to 40 prolonged and/or intense rainfall. Day found that water which are bowl-shaped, up m m

flowing down the channels ponded in the lowest parts of deep, though usually shallower at around 20 m to 25 m,

the depressions, before being removed by subsurface with depthto width ratios of <1.0. The intervening resid- of the found ual hills form small <25 with similar drainage at an outlet. Some depressions were cones, m high, - 199-

diameters the to depressions and occasionally occurring in extend to over 150 m and have a diameter of deep up- beaded wards of 1 km. The associated arrangements. residual hills are broadly

The second of dolinekarst is the conical in type common across shape, though some are elongated, 30-130 m

southern Manchester plateau and consists of enclosed and to km in diameter. high up 1 In the larger cockpits, associated with depressions elongated hills. The dimen- there is a marked break of slope at the base of the hill-

sions ofthe reliefelements similar are to the dolinekarst slope, while in the smaller depressions the floor and sides

described but the hills 300 into another previously, are up to m long, grade one (Sweeting, 1972). Although distin- and commonly orientated northwest-southeast and north- guishing between the depressions and hills ofcockpit karst

south, in to and other is since probably response major joints essentially meaningless, they are not separate structural controls. but landforms, integral components ofthe surface pitting,

A third of doline is characterised individual type landscape by cockpits are described as being surroundedby enclosed depressions with subdued hills, generally <10 m three or more residual hills of a similar elevation to the

15 where the to m high, sinkholes dominate the of the When landscape. depths depressions. the depressions are

the in Elsewhere delimited the basis Generally depressions occur clusters. on of their topographic divides, the southern Manchester across and southern St Elizabeth, surrounding residual hills and ridges connecting the

isolated dolines be identified. Some shallow constitute cellular network can are large, depressions a (Day, 1979) km features, 1 to 2 km in diameter, while others are termed polygonal karst (after Williams, 1971, 1972a). The

narrow and deep, with a depth to widthratio of 1.2 to 2.0, which depression side-slopes are convex, gives the overall with and commensurate a collapse origin possibly linked landscape a star-shaped or polygonal plan, though Che-

to well developed cave systems. noweth & that there is Day (2001) suggested a range of It is that number of likely a processes are responsible cockpit morphologies from complex star-shaped patterns

for the formation of the dolines the south across Man- to simple circular forms. The cockpits are contiguous with

chester Plateau and southern St. Elizabeth. The morphol- a clearly identifiablecol or dividebetween each depression of the ogy shallower, clustered, cone- and bowl-shaped (Barker & Miller, 1995; Miller, 1998), forming corridors dolines solutional suggests a where solution is and between hills origin, passages that connect adjacent cockpits, focussed along lines of weakness and where the vertical other divides though form saddles, which are less pro- of the limestones is permeability spatially variable. The nounced notches between adjacent hills (Chenoweth &

more isolated dolines the result Canter estimated steeper-sided, are probably Day, 2001). (1987) a frequency of 15

2 of of the km in the collapse, though many depressions are likely to cockpits per area around Quickstep, with an be of a compound origin. estimated 20 cockpits per knT in the centre of Cockpit

Country, totalling about 4,000-4,500 depressions.

The bounding slopes of the cockpit depressions are

Cockpit karst extremely irregular, although Sweeting (1958) indicated

they average about 30°-40°, consisting of chemically

Cockpit karst (Figure 4) consists of a succession of cone- weathered and honeycombed blocks and scree. Where

like hills and enclosed bedrock is the intervening depressions (Sweeting, exposed sides are steeper and form cliffs karst in Jamaica has 1958). Cockpit also been termed and precipices (Sweeting, 1972). Aub (1964a, b, 1974a, b) kegelkarst, gerichteter karst examined in detail the of different (directed karst) (e.g., array slope elements

and cone karst associated with the and six Lehmann, 1954) (Sweeting, 1958, 1972). cockpits recognised types of consideredthe Versey (1972) term kegelkarst as inappro- hillslope (Figure 5). These were defined by Aub (1964a in

priate due to the fact that the Jamaican modi- cockpits are Sweeting, 1972) as; staircase slopes, comprising small fied an of the and vertical the latter 2-3 by over-deepening depressions. Cockpit ledges steps, being up to m high karst is restricted to the fissured and and where hard, recrystallized bedding planes are conspicuous; broken cliffs,

White Limestone it does of and, as previously indicated, not consisting higher steps and less uniformledges, where

on the chalky nor does it intersected appear Montpelier limestones, the steps are by widened joints; steep even White Limestones which occur on are associated with slopes of honeycombed limestone covered with loose talus bauxite the Manchester deposits, as on plateau (e.g., and blocks; major cliffs, ofvarying height, but undercut by The overall is Sweeting, 1958, 1972). landscape a highly horizontal notches to depths of2-3 m and often associated

irregular combination of positive and negative relief with springs; cliffs of similar height but without undercut- elements of & and roughly equal prominence (Chenoweth ting; scree slopes covered with small limestone frag-

Day, 2001; Day, 1979, 1982). This type of karst landscape ments.

is the most widespread in Jamaica (Sweeting, 1958), Chenoweth and Day (2001) identifiedtwo major slope 60% of all karst terrain covering some (Day, 1979), types according to their cover, talus and soil covered

the for karst Cockpit Country being type locality cockpit slopes. The former are the more common and it was (e.g., Sweeting, 1958, 1972; Versey, 1972) (Figure 2). suggested that tree-tipping and bedrock disruption as a

The cockpit depressions are to Sweet- result of windthrow deep according may play an important role in the with of ing, an average depth 90-120 m, though they may development and maintenance ofthe talus slopes. -200-

Figure 5. Stylised cross-section ofcockpit karst, showing the mainelements ofrelief(from Aub, 1964a in Sweeting, 1972). Key: I

= soil and = vertical = cliff glade floor, with projecting rock; 2 shaft, joint-guided sinkhole; 3 over sinkhole, with gentle solution

scallops and other karren phenomena; 4 = scree slope; 5 = undercut notch at base of major cliff and associated with softer

6 = cliffwith undercut with often with case-hardened 7 = limestones; high base, scalloped or pitted surface, a surface; steep even

slope; 8 =hill summitwith projecting rock and loose fragments, some summits are planar, others more conical; 9 = pinnacles sum-

= mit surface, dissected into pinnacle and cleft ‘castles’ (may be isolated or in groups and up to 10 m high); 10 cliffwithout under-

cut from bench in solid 11 = staircase of to 3 m and to 5 base, rising a limestone; slope, consisting steps up high ledges up m wide;

12 = many of the ledges are undercut and the slopes covered with large limestoneblocks; cockpit floor, covered with soil and boul-

ders; 13 = sinkhole, vertical shaft with rubble floor and solid limestonewalls, indicating the cockpit is not a collapse feature; 14

= cockpit floor, with some joint solution and abundant rubble; 15 =broken cliffs, with honeycombed walls, narrow bedding plane

ledges and solution-controlledjoint plane openings; 16 = pinnacle-and clefttopography, with large boulders; 17 = small cockpit,

= with soil covered slopes and surface drainage channels; 18 sinkhole, impenetrable sink among boulders at the lowest end of the

drainage channels.

Chenoweth and Day also identified two basic hilltop 1977b). Aub (1964a) also indicated the cockpits he studied

in the in the around show fault and that the morphologies cockpit karst area no apparent or joint guide mor-

Windsor; some are dome shaped and rocky, while other phology ofthe slopes and cones is variable. hill summits are flatter in plan view. Smith et al. (1972) also stressed that the cockpit areas

Normally, the cockpit depressions and conical hills are show considerable variation in morphology and display more or less symmetrical, but some asymmetry occurs. irregular slope forms, though they have a mean slope

Two explanations have been presented to account for the angle of about 30°. According to Sweeting (1958), the

summits ofthe hills tend reach she asymmetry. The first is related to the dip of the to an even level, which

when it exceeds than few structural limestones, that is, more a interpreted as a surface, or part of a more exten- degrees, the cockpits become steeper on the up-dip side. sive peneplain surface, dissected by cockpits of variable

The second is differentialdissolutionrates in response to depth, representing one-cycle and multi-cycle landforms. exposure to the oncoming trade winds, as occurs near the However, Smith et al. (1972) concluded there is no corre- north coast where north facing slopes are less steep lation in the elevation of hill summits or depression floors

the to (Sweeting, 1958). Similar explanations have been pre- except where depressions have eroded down the sented for mogote asymmetry in Puerto Rico (e.g, Day, underlying Yellow Limestone.

1978b; Monroe, 1968) and a more thorough discussion of Most of the depressions ‘drain’ towards a deep vertical residual hill asymmetry is presented in the section on shaft in their lowest part eroded in solid limestone. In tower karst. The cockpits and residual hills are often some areas the shafts may have a number of narrow

which unite shallow arranged in lines following faults or jointing (Sweeting, entrances at a relatively depth (Smith

1958) (Figure 4) and the cockpit karst often occurs in the et al., 1972). Smith et al. indicated that it is possible to form of winding sinuous chains or ridges separated by gain entry to some ofthe shafts, though others are blocked glades (Sweeting, 1972) (Figure 6), though elsewhere no by debris or too narrow for exploration, contending that it structural guide can be identified (Wadge & Draper, is rare for the shafts to be explored beyond 30 m depth. -201 -

Figure 6. Cockpit karst in the north ofCockpit Country, parish of Trelawny, showing development of dissolutionwidened glades

and pocket valleys (photograph courtesy ofMr Jack Tyndale-Biscoe).

sinkholes that connect with deeper horizontal caves.

However, Baker et al. (1986) explored several of these to

depths of 80 m, without intersecting the water table, and

Canter (1987), in an attempt to estimate the frequency of

pits, indicated they reach up to 70-80 m deep, but without

significant lateral passage development with most shafts

bottoming out in narrow joints or debris chokes.

Sweeting (1956, 1958) further delimitedcockpit karst

into two variants which she termed ‘true cockpit’ and

‘degraded cockpit’. According to Sweeting, cockpits

become when due ‘slack- degraded deepening ceases to a

of solution shal- ening’ processes. Degraded cockpits are

lower with slumped and gentle side slopes, the overall

reliefof the landscape becomes more ‘subdued and roll-

ing’, and there is a greater dissociation between surface

and groundwater circulation(Sweeting, 1958). The basic

morphological difference between the two relates to the

accumulationof debris withinthe depression. The bases of

‘cockpits’ containlittle superficial material (Figure 7) and

a near vertical shaft is evident, whereas in the ‘degraded’

form the bases of the depressions are occupied by bauxitic

to material, commonly up 10 m deep (Day, 1979). De-

graded cockpit karst exhibits a wide variety of forms, in

relation to the degree of accumulation of ‘soil’, from a

nearly flatbauxitic plain with occasional protuberances of

limestone, through a vermiform pattern of limestone

ridges separated by bauxite infills, to cockpits where only Figure 7. Tower in Troy Formation showing basal undermin-

the central portions of the depressions are filled with ing, west ofLluidas Vale, parish of St Catherine.

bauxite (Smith et ai, 1972).

Versey (1972), as indicated earlier, questioned the use

indicated that floored Versey (1972) many cockpits are of the term kegelkarst to describe cockpit karst and con-

with whileothers have solid floors with vertical sidered boulders, the term to be more aptly applied to depressions -202 -

which have not undergone ‘overdeepening’, where the underground drainage. Day also concluded that the de-

are and where the forms side-slopes relatively gentle depressions graded cockpit are currently experiencing the

filledwith bauxite. mainterrain solutional attenuation are Versey proposed two greater as dissolution is focussed

of the karst karst and He beneath the types uplands, cockpit kegelkarst. superficial deposits. However, Aub, in a considered that ‘degraded cockpit karst’ represents a personal communication to Versey (1972), considered that

karst which has suffered either cockpit uplift or freeing of an important difference between cockpit karst and karst its drainage. areas elsewhere on the island was that there has never

A number of observations have been contrasting made been a bauxite cover in the former and dissolution has a about the characteristics of hydrological the cockpit karst. more powerful effect than in areas where the depressions

Zans noted instances in the infilled (1951b) which depressions are are with bauxite, thus inhibiting dissolution and

flooded rainfall and similar partially following heavy impeding deepening. It is clear that more work needs to be observations have been made who done by Sweeting (1958), on the relationship between the bauxite cover and noted karstification of the temporary ponded water, though frequent flooding limestones, but, as indicated in an of cockpits only occurs when they extend near to a level earlier section, work subsequent to that of Aub has shown

close to underground water circulation. that in most the Versey (1962) cases presence of a soil cover enhances described the flooding of cockpits after heavy rainfall, dissolution (Trudgill, 1977). where issues from basal water sinks which at other times A number of explanations have been given for the drain the and Aub cockpits, (1974a, b) noted the presence origin of the cockpits, but they basically fall into either of small channels leading to a central depression with solution-relatedor collapse-related categories. The origi-

surface after rainfall. Aub nal for the temporary drainage heavy collapse explanation cockpits was presented by found the receive (1964b) depressions 13-15% more Sawkins (1869), where in the first detailed descriptions of than the hill summits precipitation and suggested that The Cockpit Country, the depressions were ascribed to the

of rain into the vegetation rafting water cockpits by sinking of water through the cavernous structure of the

led to dissolution there. Smith throughfall being greater et limestones, which forced its way through and subsequently al. (1972) notedthat the presence ofnear-vertical shafts in removed underlying beds of shale and sand of the ‘Trap- the bottom of would surface but Series’. The cavities cockpits suggest runoff, pean formed were unsupported and

found evidence of flow in the shafts and form they no recent no collapsed to the cockpit depression. Some thirty surface runoff, other than in a few locations where a thin years later, a lengthy reassessment of the geology of soil is cover present, when small channels develop and Jamaicawas published by Hill (1899), who, although there become locally active. They also found no well developed was little descriptive interest in the karst, ascribed the channels in the degraded cockpits and no evidence of origin of cockpit depressions to dissolution rather than flooding. In contrast, Day (1977, 1979) noted occasional collapse. Danes (1909, 1914) was the first worker to basal in ponds ‘degraded cockpits’ and small channels cut widely adopt the theory that the cockpit depressions into the bauxite but superficial cover, not extending onto originated predominantly by dissolution of the limestones limestone bedrock, where water disappears by vertical along fissures and other lines of weakness, though he did infiltration. in the Similarly, ‘cockpits’, slow vertical concede that they may be further deepened by localised

is the dominant percolation hydrological process, no collapse of caves which would help to further enlarge surface flow either in occurred, dispersed or surface them. Using evidence such as the regular distributionand

the shafts inactive channels, are and essentially relict linear arrangement of the cockpits, together with their

(Day, 1979). dissociation from subsurface groundwater circulation,

Surface channels similar those in drainage to New Sweeting (1958) also concluded that the cockpits are

Guinea formed cockpits (Williams, 1971, 1972a, b) are virtually by dissolution with subsequent enlargement by absent in the Jamaican cockpits and are confined to the collapse along fissures. Versey (1962) suggested that the superficial cover in the ‘degraded’ forms. According to physiography ofThe Cockpit Country is closely related to the shafts Day (1979), once acted as drains at the foci of the hydraulic and abrasive action offloodwaters in under- surface channels under conditions of either lower and that solutional secon- ground drainage systems, and me-

and/or a wetter climatic dary permeability regime. It is chanical action of confined floodwaters was responsible highly likely that the vertical shafts developed due to for the enlargement of cockpits, along with collapse. surface Gardner al. also noted that drainage and, according to et (1987), Versey the deepest cockpits occur where the vertical shafts in Jamaica may have developed because underground water movement is close to the surface, and ofthe relief greater available, due to more recent tectonics, he further refined this theory by suggesting that a rise in

because the limestones or are more dense than in Puerto water levels during rainfallbrings groundwater circulation

Rico, where shafts are seldom found. It could also be the close to the bottomof the cockpits, eroding them, and that

case that shafts in Puerto Rico are obscured by debris. subsequent collapse then deepens the depressions and The hydrology of the cockpits is now dominated by removes the soil cover (Versey, 1972). According to slow and diffuse which is the ifthe have percolation, only contempo- Versey, cockpits developed over a long period connection between the rary cockpit depressions and of time, then the rate of erosion has matched the rate of -203 -

uplift. In areas where uplift has been more rapid, water size and shape of the intervening residual hills (Figure 8).

circulation becomes too deep to be effective, then dissolu- The three types are: cockpits with conical hills; cockpit

tion takes over as the main erosive process and a soil cover depressions with small elongate hills up to 50 m high,

develops in the depressions leading to the development of aligned in a general north-south direction, probably along

‘degraded cockpit karst’. faults and major joints; and depressions with larger elon-

Other workers have that dissolution suggested alone is gate hills in a beadedarrangement, grading intoridges. A

for formation.Aub responsible cockpit (1964b) suggested recent survey of ‘cockpit karst’ terrain in the south of the

there is little evidence of in of southern Elizabeth very any widespread collapse or island, parts Westmoreland, St

mechanical action, and that there is no correlation of and Manchester (Sir William Halcrow & Partners, 1998),

size with above the classified the based the cockpit shape or height underground cockpit landscape on presence or

Aub further indicated that the absence of surface drainage. depressions an integrated drainage pattern across receive more throughfall than the hill summits and sug- the terrain, on the size and shape of the intervening hills

gests that solution could be greater in the depressions and on the extent of the enclosed depressions, especially

which makes them self-perpetuating features. Aub also whether or not they contain a residual soil infill. In this

link attempted to the development of ‘degraded cockpits’ study, an area of cockpit karst to the east of the Cabarita and the of where he considered that occurrence bauxite, River, parish of Westmoreland, is associated with ephem-

the shallower the result of sediment eral cockpits are greater drainage lines, comprising gullied slopes and dry,

within and associated with short deposition them, they are parts valley systems, often draining to larger interior of the Central Inlier that breached first. He further and of were valleys poljes. Most these drainage lines are proba-

suggested that if this were the case then the ‘degraded bly inactive and the landscape is partly relict terrain.

be from ‘normal’ cock- indicated cockpits’ may not a development Versey (1972), as earlier, suggested that the

pits, but have a different history. Smith et al. (1972) and term ‘kegelkarst’ is an inappropriate term for the over-

Day (1979) also supported a dissolution origin for the deepened cockpits within The Cockpit Country heartland,

development of cockpit karst. and that it is more appropriate to use the term for the

Two geomorphological aspects of the cockpits which ‘degraded’ cockpits around its margins. It is evident that

have been overlooked are the of me- the used needs to be cleared and to largely importance terminology up, help

chanical breakdown to their development and modifica- overcome terminological confusion some workers have

tion, and possible fluvial inheritance. Many ofthe cockpit turned to morphometric analysis to develop a more objec-

slopes are strewn with angular, block- and boulder-sized tive classification of the terrain (e.g., Day, 1979, 1982).

talus and which be scree cannot explained by simple This and other morphometric approaches to the study of

dissolution and the of mechanical and other karst terrain processes, importance cockpit types in Jamaica will be

breakdown actively modifying the landscape has been discussed in a later section.

understated. These talus-strewn slopes may be the result

of bedrock disruption by the windthrow of trees (Che-

noweth & Day, 2001), while dissolutionalong joints and Tower karst

bedding planes could increase the susceptibility of the

cockpit slopes to rockfall. Some ofthe cockpit depressions Lehmann (1954) described the geomorphology of tower

have a beaded arrangement, others are linear in nature, karst (Tumi karst or Mogote karst) in Jamaica, which

whilethe cockpit karst landscape often occurs as winding comprises a landscape of residual hills scattered across a

chains sinuous channels or ridges separated by and glades, relatively flat plain (Figures 9, 10). Some of the residual

the of The The isolated particularly at margins Cockpit Country. towers are and others occur in groups. They occur

fluvial inheritance geomorphology suggests a possible to on the crystalline White Limestones, but tower karst is

the least in Aub’s much less than karst cockpit landscape, at some parts. widespread cockpit (Sweeting, 1958)

(1964b) suggestion that ‘true’ and ‘degraded’ cockpits (Figure 2). According to Sweeting (1958), towers are

have different also further hills which to a evolutionary history requires steep-sided slope up 60°-90°, rising up to

investigation. 100-150 m above a flat alluvial plain. The towers are sub-

From the foregoing, it is clear that cockpit karst has a conical, though many have flattened tops and appear

wide of form and several tabular in The variety interchangeable terms profile. tower slopes are frequently broken

have been used to describe the ‘cock- and devoid of soil landscape, including a cover, except for isolated pockets.

pits’, ‘kegelkarst’ and ‘conekarst’, while ‘true’ cockpit Many tower bases are underminedand display undercut

karst and ‘degraded’ cockpit karst were additionally notches associated with well-developed foot-caves and

introduced to differentiate between cockpit depressions springs (Figure 7). A well-developed ring of sinkholes,

devoid with soil and debris Pfeffer of, or a cover. (1969, which oftenbecome flooded in the wet season, commonly

1984) identified distinct variants of cockpit (Kegelkarst) occurs around the base of the undermined and over-

in southwest Jamaica and, more recently, Miller (1998) steepened towers. Indeed, some of the towers are situated

mapped three principal classes of cockpit karst in The in small enclosed depressions, similar to those described

between Windsor and based the Cockpit Country Troy, on on alluvial plains in Belize (McDonald 1975, 1976). -204-

Figure 8. Geomorphological map ofthe area ofCockpit Country between Windsor and Troy, parish of Trelawny. -205 -

Figure 9. Tower karst in MoneagueFormation with basal pedestal in plane limestone, south Manchester Plateau, parish of Man-

chester.

According to Sweeting (1958), two particular geologi-

cal conditions favour tower karst development. They occur

near to the base ofthe White Limestone at thejunction of

the Yellow Limestone and within the crystalline facies of

the White Limestone Group in close association with the

marly Montpelier Formation. They are also associated

with rapid spring-head recession, which gives rise to the

flat-floored, steep-sided and steep-headed ‘pocket valleys’

which accompany tower karst on the northern margins of

Cockpit Country (Sweeting, 1958). Sweeting (1972)

further identified two main types of tower karst, which

both occur withinthe White Limestone Group. One type

of tower occurs as a visible remnant of limestone sur-

roundedby alluvium, beneath which is a planed limestone.

The other tower type is developed on a plain of non-

limestone rocks, as occurs where towers within the White

Limestone form outliers on the much less pure Yellow

White Limestone, though they may also occur where the

Limestone is in faulted contact with older Cretaceous

rocks, especially in the Central Inlier. Draper & Fincham

(1997) indicated that isolatedtowers of White Limestone

formed by erosion downto the less soluble YellowLime-

stone or older Cretaceous rocks are best developed around

the ofThe Coun- Maroon Town, on western edge Cockpit

while the other tower with residual hills try, type, pro-

truding through an alluvial blanket in a glade, polje or

plain is well developed in the Cave Valley area and on the

western edge of Lluidas Vale. Draper & Fincham (1997)

have observed of shelter at the base Figure 10. Case hardenedtower karst in MoneagueForma- many examples caves with solutional and tion, south Manchester Plateau, parish ofManchester. of the towers, pockets anastomoses, -206-

solutional the base of the suggesting undercutting at east-west asymmetry, where the west facing slope (60°) is towers. about 25° Pfeffer steeper. suggested aspect related mois-

In addition undercut with to towers notches, Sweeting ture changes as an explanation for the asymmetry, where

identified second rainfall (1958) a tower type based on morphol- evaporates more quickly on the east-facing slope

which she to ogy, interpreted be ‘degraded tower karst’ and with it corrosive action is impeded. Pfeffer also noted

These where the lower dis- that the (Figure 2). are towers slopes west-facing slopes have a conspicuously thicker play slumped sides, and the sharp break of slope at the case-hardened caprock. undercutbetween the tower base and alluvial floor karst in disap- Similarly, east-west tower asymmetry Puerto from decrease pears, resulting a in limestone dissolution Rico has been linked to the dominantwind direction and

the foot ofthe due at tower to a cessation of flooding ofthe resultant differential dissolution and reprecipitation of alluvial area. calcium carbonate. Gentler slopes on the eastern sides of

Some towers show little evidence of and towers have been related to the increased undermining, exposure to contain colluviated footslopes or of blocky lime- rainfall and dissolution while the aprons (Thorp, 1934), asym- talus stone and scree, sloping upwards of 25°-30°. These metry has also been linked to variation in the extent of

the western of Lluidas Vale at are seen on edge higher case-hardening (Monroe, 1966, 1968). In this case, the altitudes than the level of alluvial within the rim of indurated current cover caprock is thicker on the eastern side and vale. be similar the thin case-hardened They may to towers at interfluve locations surface on the opposing slope tends in where McDonald showed that the the Belize, (1979) mor- to spall-off slope, leaving a vertical cliff and over-

of located interfluvial is in phogenesis towers on plains hanging slopes. Day (1978b), a study ofthe mogotes on controlled the of the by progressive lowering alluvial the Aymamon Limestone in northern Puerto Rico, showed surface by erosion due to overland flow, and the tower- that tower is not asymmetry as simple as previously sug- base landforms revealed colluviated bare the do the are gentle, or gested, as steepest slopes not always occur on bedrock As the interfluve eroded and side of the found different footslopes. plains are western towers, but are at lowered, bedrock slopes are formed around the towers locations around the towers that towers, including many with which rise a slope angle approaching 20°-60°, to displayed a north-south asymmetry. Day linked the asym-

the base of cliffs about 10-50 above the surround- meet m metry to concentrations of sinks in particular locations

The the interfluve therefore ing plain. towers on plains are where tower slopes became underminedby both corrosion not the result of tower undermining and lateral planation, and mechanical action. The geological dip is also to the but formed the vertical dissection of the north in this and it be are by plain area might expected that water sediments. would movement be in that direction, leading to a con-

The karst in the White centration of sinks most common tower on the steeper southern slopes. Day

Limestones involves residual hills from either considered that the of the protruding general dip strata may also a planed carbonate surface veneered by alluvium or from contribute to the asymmetry, though this is generally <5°.

alluviated surface limestone. In the of the Bull an burying a pinnacled Many case towers near Savannah, parish of St of the have been case-hardened towers and two morpho- Elizabeth, Jamaica, the present author considers the

of logical types tower associated with an alluvial infill asymmetry is related to the dip of the limestones, which from be allogenic streams can recognised, namely circular dip about 10°-15° to the east and southeast. Thus, the and Both of elongate (asymmetric) towers. types tower are steeper slope facet is on the up-dip side of the tower and formed directed solution by laterally at or near to the water suggests a strong structural control in the morphogenesis table, coupled with aggressive floodwaters from allogenic of the towers. rivers. towers to Small Symmetrical (circular) are commonly up towers, from 5 to 20 m high and 100 m or less

100 m elevationand 1 km in diameter with steep, almost in diameter, together with asymmetric and elongate forms vertical and with associated sinks and similar the slopes depressions to Pepino hills ofPuerto Rico, are common on around their bases. They may occur singly or in small the plateau surfaces and slopes of southern Manchester clusters. tend be and southern Asymmetrical or elongate towers to larger St Elizabeth, developed chiefly on case and be can over 1 km long with a length to widthratio in hardened Moneague Formation limestones. They were

of 2.0. excess Asymmetric towers occur where one slope described by Pfeffer (1967), where small isolated towers facet exceeds the than 20°. There associated with opposite aspect by more are corrosion surfaces and what he termed is trend in ofthe orientationof no general terms elongate Kuppenruinen (which literally means ruined hilltops),

but where in clusters the south which small towers, they occur across are basically towers up to 8 m high and <100 of the their broad island, arrangement is northwest- m in diameter (Figure 11). The towers in this area are southeast and north-south. the Elongate towers occur on unusual in that they are not associated with low-lying slopes to the west and northof Alligator Pond and around alluvial plains close to base level. Pfeffer (1975, 1997),

Bull with where the relief Savannah, an east-west asymmetry, through analysis near Mandeville and Alligator is than the west-facing slope steeper slope on the eastern Pond, considered that the karst in that area had been side. These tower-like hills were described by Pfeffer uplifted during the Quaternary, when they were lifted well

(1967) as being only about 10-12 m high, with striking above the regional groundwater table. The mode of for- -207-

mation of these towers is still uncertain, as some are aligned roughly along northwest-southeast and northeast-

with oversteepened footcaves, indicating active or rela- southwest axes, probably in response to major joint and

tively recent undermining, whereas other towers, in the fault trends. A second set of predominantly east-west

same area, rise above small limestone pedestals (Figures trending ridges displaces the north-south ones, in the area

the of 9, 10). The towers are probably product vertically between Top Hill, Ballards Valley and Bull Savannah,

directed dissolution processes rather than corrosional parish of St Elizabeth. The development of the limestone

at water planation or near the table. They are therefore ridges appears to be related to the prominent faults, where

similar in origin to towers in northern Puerto Rico, where the faulting leads to a marked resistance of the limestone

there is a concentrationof water within the coversands at around the fault to weathering. The exact mechanism of

the base the and directed solution their formation of towers vertically requires more detailed investigation,

controlled by the presence of depressions and sinkholes, although Versey (1972) attributed this resistance to disso-

concentrating erosion at the tower base (Miotke, 1973). lutionas a result of reduced permeability around the fault.

Some of the towers on the plateau surfaces and slopes above local base level in southern St Elizabeth seem to be

aligned and are separated by corridors where the topogra- Glades

phy is less marked. The tower alignments correspond to

directions. have major joint They may evolved in a similar Glades were first described by Sweeting (1958) as elon-

fashion the to giant grikeland or labyrinth karst in the gated and enlarged cockpit depressions, similar to uvalas,

Nahanni region of northern Canada (Brook & Ford, where individualcockpits extend by growth along lines of

where controlled 1978), joint grikes are opened up by jointing and faulting, and coalesce to form more complex

dissolution form enclosed to depressions with steep, forms along a well-defined tectonic line. Glades and residual towers to from up 50 m high, emerging a devel- cockpits tend to merge into one another (Sweeting, 1972).

karst The corridors between the oping, uneven plain. Sweeting indicated that Barbecue Bottom (Figure 12), in

be similar the the northeastern aligned towers may morphogenetically to part of Cockpit Country, is a typical glade

ofPuerto Rico formed in such zanjones (Monroe, 1968). a way along a northnortheast-

southsouthwest-trending fault line. According to Sweeting

(1972), glades are sinuous depressions with concave and

karst and sided. The floors of Ridge angular contours, are steep glades

also tend to consist of a series of shallow basins being

A numberof limestone ridges have been recently reported separated by low divides which are much shallower than

across southern St Elizabeth and to a lesser extent on the the passes leading out of the glades. Sweeting also indi-

Manchester plateau, in the Moneague Formation cated the contrasting drainage of cockpit depressions and

limestones (Sir William Halcrow & Partners, 1998). They glades, in that drainage of cockpits tends to be toward the

described Pfeffer were initially by (1967), who noted a centre, whereas drainage in channels on the floor of the

of range narrow ridge-like horsts and what he termed glade often disappears into caves and sinkholes at the

associated with of Kalkrippen (limestone ribs), commonly margin the glade. Glades have also been described as karst corrosion the south of southern St broad surfaces, to Nain, areas betweenresidual hills that can individually be

Elizabeth also notedthe classified (Figure 11). Versey (1972) occur- as either compound depressions, such as uvalas,

‘fault-line associated low- and underdrained rence of ridges’ with or as dry valleys (Chenoweth & Day,

faults that have resisted he their permeability erosion, though 2001). Accordingly, cross-profile may be flat, con- did not indicate their precise location. The karst limestone vex, concave or undulating, and in plan view their shapes ridges in the parish of St Elizabeth are up to 4 km long, are either linear or sinuous. According to Chenowethand

but more commonly 0.5 to 2 km, and from <50 to 300 m Day, many glades have thick soils and when left undis-

with from wide, heights ranging <5 to 40 m. Some are turbedthey support large trees and dense vegetation.

topped by limestone exposures in the form of rock walls.

They occur across a variety of geomorphic settings on Poljes

plateau surfaces, slopes, broad depressions and on valley

floors. They particularly occur in topographically low- Poljes are large, flat-floored, enclosed depressions in karst

lying settings to the south of Burnt Savannah, parish of St terrain, commonly with ephemeral or perennial streams

Elizabethand the to east of Santa Cruz, where they disap- flowing across their surface (Ford & Williams, 1989).

northwards beneath the of the Black have pear swamps upper Poljes three diagnostic criteria (Gams, 1978): a flat

River also associated with of floor morass. They are a range in solid rock or unconsolidated sediments such as

other karst closed basin bordered landforms, including dolines, elongate hills, alluvium; a by a rim of steep mar-

uvala-like enclosed and the be restricted large depressions, dry valleys ginal slopes, though steep slope may to karst. tower one side of the polje, with an abrupt break of slope be-

of the Many ridges are broadly symmetrical, though tween the floor and sides; and karstic drainage with

others their are asymmetrical across axes. Most are stream sinks, especially at the margins of the polje. -208 -

southwest Manchester and southeast St Elizabeth from Figure 11. General geomorphological map of (redrawn Pfeffer, 1967). Key: 30-50 2 = karst residual hills to = cone m 1 karst marginal plain - alluviated karst plain (Karstrandebene); (Kegelkarst): (a) up

residual hills, to 8-12 m elevation; 3 = corrosion surface elevation, high relief on gentle slopes; (b) tower-like up (Korrosions-

and 5 = karst = (b) landslides; flache); 4 (a) small steps, narrow ridge-like horsts and limestone ribs (Kalkrippen); escarpments

plateau (Karstebene). -209-

Figure 12. Glade at Barbecue Bottom, northern Cockpit Country, parish of Trelawny.

13. at Lluidas of St Figure Polje Vale, parish Catherine, displaying gently undulating floor with subsidence doline and steep-sided rim in part due to faulting.

The or ‘interior ofthe island have poljes valleys’ been (1972). Specific poljes have also been studied in more described in and general by Sweeting (1958) Versey detail, especially The Queen of Spain’s Valley (Pfeffer, -210-

1986) and Lluidas Vale (Landmann, 1985, 1990) (Figure Lateral planation at the margins of the polje has resulted

in dissolution within 13). Sweeting (1958) indicated that poljes occur Ja- in the of cockpits and their integration maica where lithological, structural or relief conditions the polje (Landmann, 1985). According to Landmann

is the permit flood water to collect and where rapid drainage (1985), a lowering of the base level has lead to polje

the channels and sink- impeded. Accordingly, they are conspicuous along becoming more dissected, forming northern of where lateral holes. the table is margin Cockpit Country, water At present permanent water at some movement is promoted by the Montpelier Formation depth beneath the polje surface and it is more likely that chalks, and on the northern side of the Duanvale fault local perched water tables within the alluvium account for

also noted lateral after rainfall. Landmann zone (Sweeting, 1958). Sweeting (1958) poljes planation heavy (1990) to be common where the White Limestone Group comes further developed his theory ofpolje formation at Lluidas into contact with the older Yellow Limestone Group, Vale in relation to changing climatic regimes. He attrib- where flood water be due to uted the landforms around Lluidas Vale to different cli- can ponded poor drainage through the older rocks. Sweeting (1958) further sug- matic regimes, in that intensive weathering conditions in

the the island the formed and karst gested that, as poljes across occur at a range ‘Neogene’ etch-plains cone sur- of elevations, local water table fluctuations were more rounding much of the Vale, while alluvial fans and

dolines the drier important to their development than regional variations. in Vale represent climatic conditions and

She also noted the occurrence of drained poljes where a lower intensity of weathering in the Quaternary. Ac-

is absent due Landmann the is the result of flooding or occurs infrequently to changing cording to (1990), polje hydrological conditions and marginal poljes (border lateral expansion of the limestone at or near the water poljes) where they are not completely surroundedby White table and began as ‘the meandering canyon of a river’.

Limestone. Pfeffer(1986) described the Queen of Spain’s Valley

According to Versey (1972), all of the poljes are as a large polje with an extensive plain, about 90-100 m structurally controlled in their entirety and there is no elevation, surrounded by higher relief. To the south, the evidence erosional down- is bordered limestone hills which rise to suggest an origin. They are valley by steep faulted on at least one side and the characterof the fault- abruptly to form cockpit karst; to the north, east and west, ing tends to impede drainage, which forces groundwater the polje gives way to limestone hills and dolines. Ac- to the surface during high water stages. The drainage may cording to Pfeffer (1986), the polje floor is dissected by

such the reversal of which contain shallow and be impeded by a structural control, as dolines, may ponds, many

dip, by the upfaulting of the karst base (Gardner et ah, karst springs rise on the polje floor near to the southern

in border flow northwards the River and 1987), or by an abrupt decrease limestone permeability to as Roaring Mar-

Some alluviation tha Brae River Pfeffer the (Versey, 1972). poljes are prone to systems. (1986) interpreted

during floodevents, especially in low-lying areas, while in landforms of the Queen of Spain’s Valley and the sur- others the alluvium is being dissected. In some poljes, the rounding karst landscapes as the result of different relief up-slope part of the valley is periodically flooded and generations, possibly influenced by tectonic uplift and subject to deposition of alluvium, while the down-slope climate change. He considered that the polje and the area carrying floodwaters to sinkholes is being dissected surrounding cockpit karst are Tertiary landforms, and that

(Versey, 1972). The poljes are generally linear, with the subsequent Quaternary uplift and climate change led to long axes perpendicular to overall direction of groundwa- the development of the dolines, dry valleys and subdued

described limestone hills the northern border ofthe ter flow (Gardner et ah, 1987). Versey (1972) forming polje, a

similar that some of the best known poljes on the island including the interpretation to of the evolution of Lluidas

Nassau Valley and the interior valleys of northern Vale given by Landmann(1990).

Trelawny. He considered that faulting and folding within In Jamaica, the three basic types of polje outlinedby the Nassau Valley forms a barrier to drainage and forces Ford & Williams (1989) can be identified, these being

groundwater to the surface, which causes periodic flooding border, structural and base-level poljes. Border poljes and leads to the deposition of alluvium. In describing the receive allogenic drainage from a non-carbonate area and

ofnorthern indicated that therefore bordered all sides limestone. The valleys Trelawny, Versey (1972) are not on by the structuralbarrier which impedes the northerly flowof valley floor contains a number of allogenic streams which

groundwater, leading to a series of springs, is a combina- bring alluvium onto the polje and eventually disappear at tionof an upfaulted block of Yellow Limestone beneath stream sinks (ponors). A typical border polje occurs at

of facies within the White Lluidas Vale. Structural dominated the valleys and the change poljes are by geologi-

Limestone from the crystalline and rubbly limestone to the cal control and associated with graben or fault angle

Montpelier Formation chalks. depressions formedby block faulting. Structural poljes are

According to Landmann (1985), lateral planation was common across the White Limestone. Base-level poljes are

Lluidas of responsible for the development of the polje at common to the north Cockpit Country, though here

Vale. The process takes place at the borderof alluvial fans they are also associated with faulting. Base-level poljes are

the the and in small in water table on floor of depression areas a dominatedwhere the regional epiphreatic zone

karst to the southwest of the Vale. the neighbouring cone area reaches surface. They are typically located on the -211 -

outflow side of the karst which drainage, partly explains are associated withresidual tower karst emerging above

their occurrence to the north of Cockpit Country. the alluvial cover.

karst Incipient (weakly developed) terrain Limestone valley systems and otherfluvio-karst

There number of massifs within the and are a upstanding Dry ephemeral limestone valley systems and lime-

White Limestone the southern Group, mostly across stone gullies are quite common across the White Lime-

sections of Jamaica, where karstification is restricted to stone Group outcrops over the island, but very few have

small-scale dissolution about 1 2 been described in detail. sculpturing, to m deep, Allogenic streams, blind valleys,

extending to a maximum of about 5 and m, accompanied by steepheads pocket valleys also occur, the latter having

the of a case-hardened surface. also been described development They are by Sweeting (1958) from around the mar-

often covered limestonetalus and and have of northern and by scree, may gins Cockpit Country were further briefly limestone debris fans on their lower slopes associated with examined Miller Gullies by (1998). and gorges are com- dry valley and Uncommon systems gullies. sinkholes, mon on the limestone outcrops to the south of the island, dolines and collapsed ephemeral surface drainage lines are and are an of or in expression ephemeral drainage may associated with the karst incipient surfaces of these lime- some cases be relicts of wetter in the recent periods geo- stone massifs. locations include the Dallas Moun- Gullies Typical logical past. drain the southern part of the south Hellshire tain, Long Mountain, Hills, Brazilletto Moun- Manchester plateau, especially in the Robert’s Run-

Portland Round Hill and Great Sixteen Mile tains, Ridge, Kemps Hill, Gully area. Some ofthe gullies on the south-

Goat Island. have end of the Manchester Although they poorly developed surface ern plateau are associated with of the massifs have well karst, some developed cave alluvial fans that have been slightly displaced by faulting,

such as the Jackson’s Great Cave Port- that the systems, Bay on suggesting faulting is a relatively recent occur- land Ridge The surface karst (e.g, Fincham, 1997). poor rence, though no detailed work has been undertaken to

development on these massifs could be a factor of the date.

duration that have been to sub-aerial weath- examined the limestone they exposed Day (1985) valley systems

ering with most been in rela- the north where processes, having uplifted along coast, particularly they are well tively recent geological time. developed between Discovery Bay and St Ann’s Bay where seventeen major valley systems extend up to 7.5 km

inland. Streams in these valleys range from permanentto

Karst low times surfaces of relief(buried karst) mostly dry, except at of intense or prolonged rain-

fall, while others show alternate wet and dry reaches. The

Both buriedand karst surfaces of low relief headwaters of the exposed are most extensive valley systems are lo- extensive in the and lower of upper morasses the Black cated in the so-called Browns Town-Walderston forma-

River. This described Pfeffer area was by (1967) as a karst tions (now the Moneague Formation; Mitchell, 2004), which is marginal plain (Karststrandebene) (5), basically though much of their valley length is across the Mont-

an alluviated karst plain. Karst surfaces are also exposed pelier Limestone, and they are associated with a series of above the blanket of alluvium in the CabaritaRiver imme- gravel fans of Quaternary age near to the coast. Day diately west of where the north-south Savannah-la-Mar, investigated the geomorphology of the valleys and exam- of the surfaces alignment exposed may be a response to a ined their morphometric properties, including drainage structural control. Karst surfaces of low relief also occur density, valley order and orientation.Two distinct valley aroundLittle of where orientation concentrations London, parish Westmoreland, they were shown, one virtually

are associated with a thin alluvial cover and normal the coastline numerous to present (north-south), and a sec- enclosed water-filled depressions. ond which parallels the coast (east-west). Day compared ofthe karst Many surfaces be a of a former the with may legacy valley systems similar dry valleys developed on

polje surface, now covered by alluvium and wetlands, such the raised reefs in Barbados (Fermor, 1972) where the

as the lower of the Black River morass (Grontmij, 1964; drainage pattern was attributed in part to the effect of

An alternative is that raised reef Pfeffer, 1967). explanation they morphology on drainage extension across the buried base level corrosion represent partially plains, reef during surface runoff under wetter conditions than while allogenic rivers across the former indicated that the Barbados model flowing polje present. Day can only aided in the be for planation process by periodically introducing invoked the valley sections across the raised reefs

volumes of Corrosional and that the large aggressive floodwaters. east-west valley orientations are structurally have also been planation may encouraged by the sandy controlled due to east-west faulting in the Duanvale Fault bedload of the rivers. In overbank addition, deposition Zone. Control on the north-south valley trends is less would stimulate biochemical activity on the floodplain but considered clearly explained, Day that they may either and, through the production of soil carbon would be dioxide, joint controlled in a similar way to zanjones in Puerto enhance soil of the karstic water impacts. Many surfaces Rico or be related to north-south faults. -212-

Smith & Atkinson (1976) described the landscape contact between the Montpelier Beds (Montpelier Forma-

fossil fluvio- and the White Limestones. developed on the Montpelier Limestone as a tion) crystalline Sweeting

network. furtherindicated that karst with a well-integrated dry valley Day (1958) most cave passages are fairly

tunnel-likecross-sections and floors (1985) considered the valley systems to be fossil in that long, with undulating

of their be attributed due the of roof-fall debris certain components may to past to common occurrence (break- conditions and that little devel- for the inclined they are undergoing or no down), though most part gently passages opment under most present conditions, though during predominate similar to the generally shallow gradients of prolonged or intense rainfall they are fully active, so it underground water flow. would be incorrect to describe them as totally fossil. The According to Draper & Wadge (1997), most of the

limestones extensive gravel fans on their lower reaches were also explorable caves occur in the shallow water taken to indicate greater transport ability in the past. Day which are commonly crystallised to at least 40% sparite.

(1985) examined the sources of runoffwithin the valleys, There is also evidence to suggest that the sparite-rich

surface runoff after limestones resistant solutionthan the micritic which comprise two components, are more to rainfall and water supplied by underground drainage limestones with low sparite content and tend to produce

baseflow for the that taller than are wide and are sources, the latter providing the perma- cave passages are they nent streams. Some of the baseflow is supplied from more strongly joint controlled (Wadge & Draper, 1977a). adjacent enclosed depressions and sinkholes via springs Wadge & Draper (1977a) investigated the size and

of cross-sections in several formations within the valley courses (Day, 1976, 1978a, 1984), shape cave passage though much is derived from the limestone and non- of the White Limestone Group. They found that most carbonate the south of the The dominant of in the oldest areas to valleys. caves great length occur Troy Formation formative mechanism for the valley systems was thought (and in the Chapelton Formation ofthe Yellow Limestone to be fluvial erosion rather than karst solution (Day, Group), associated with allogenic rivers flowing off the

1985). Cretaceous inliers to form stream sinks. Thus, the large

formations Miller & Donovan (1999) examined the Natural cave passage lengths encountered in these may

than Bridge at Riversdale, parish of St Catherine, which occurs be under stratigraphic rather lithologic control,

to in a small gorge cut into limestones of the Somerset and related water flow routes. Wadge & Draper (1977a)

section of further indicated that cross-sections within Troy formations. The bridge spans a 20 to 22 m cave passage

with distinct the Formation in the Rio Doro channel and is 17 m high a Troy are typically rectangular shape,

and control. The limestone bed forming the roof span. The natural bridge indicating a strong bedding-plane joint

of roof of in the Swanswick was inferred to be the result partial collapse an biggest cave passages occur Formation,

river while river also formed underground system, capture may typified by huge, single-passage dip-tubes along have contributed to its formation through the work of a major phreatic routes, possibly related to the massive more aggressive lower base-level capturing stream. Miller bedding and lack ofjointing within this formation(Wadge

& Donovan further suggested that initial collapse probably & Draper, 1977a). formed karst windows that were subsequently connected The tectonic control on cave development was also

little by more complete collapse to form the gorge. investigated by Wadge & Draper (1977b) who found

fault evidence of caves along major planes, though some

be small faults. few river caves may along subsidiary A

of do fault Cave systems and underground rivers caves steep gradient occur alongside major

systems (e.g., the Bristol Cave-Quashies River Cave

of and the of & faults tend to A summary cave exploration development system) (Waltham Smart, 1975). Major

studies within Jamaica features where speleological was presented by produce large collapse especially they

Fincham (1997). The first detailed speleological studies of intersect cave passages at high angles, while strike-

cave systems within the White Limestone Group were passages and dip-tubes tend to develop where drainage is published in the 1950s (e.g., Zans, 1951b, 1953, 1954a, b, parallel to strike (Wadge & Draper, 1977b). The most

is the river 1958a, b, 1959). White & Dunn (1962) indicated that the important cave type fairly straight, large

to with little in and down largest caves appear be single cave passages passage, simple plan flowing dip. According or no branching. Brown & Ford (1973) investigated the to Wadge & Draper (1977b), although phreatic ‘lift’

and associated in northern would be in where the caves groundwater patterns passages expected to occur caves

is less than the of the Jamaica, and the hydrological link between the Quashies hydraulic gradient dip beds, only a

River sink and the Domock Head rising. few exist, as they may have become fragmented and

that known in disconnected surface such that Sweeting (1958) suggested most caves by rapid lowering, re- the White Limestone Group are located in two main maining passages only occur within inter-depression hills.

horizontal in of stratigraphic locations: first at the contact between the Although some passages occur areas

lower formationsof the crystalline White Limestones and cockpit topography, these are essentially fossil features, the top beds of the older Yellow Limestones (Troy Forma- cut by later erosion ofthe karst surface (Draper & Wadge, tion/Chapelton Formation); and, secondly, at the zone of 1997). -213-

In terms of vertical cave number development, a large and considereda compound origin was likely. of shafts ‘cockpit’ are known within the White Limestone Day (1979) used vector analysis to examine the distri-

Group, and many have been explored, described and bution and orientation of planar surfaces within several

Most shafts surveyed (Fincham, 1997). cockpit are re- sampling areas across the Caribbean, including localities

to be solutional in block- and boul- the White garded origin, though on Limestone, to develop a surface roughness

der-chokes within shafts index in order many may indicate some col- to classify landforms on a more objective There also lapse. are a significant number of caves with basis. Day calculated the surface roughness values ofthe

both vertical and sub-horizontal which sites threefold passages, seem to ten to develop a classification ofthe land- be concentrated in specific areas of steep hydraulic gradi- scape, the three types being roughly equated with doline

ents and where is faulting prevalent (Wadge & Draper, (type I), cockpit (type II) and tower (type III) morpholo-

caves are abandoned vadose 1977b). Many systems de- gies. Day (1982) developed an additional general classifi-

scending in a series of shafts. Wadge & Draper (1977b) cation index from Caribbean-wide karst terrain, which that the of these vadose suggested development steep analysed different degrees of theoretical roughness and

systems may have been related to the presence of thin, simulated overall karst landscapes. The negative and bentonite impermeable near the of the relief of the clay layers top positive elements landscape were analysed to

White Limestone which would have ratio of vertical horizontal Group, provided develop a to components. On sufficient concentrationof surface for the basis of drainage to account the ratio oftheir vertical component compared

the vadose with their steep cave development. Elsewhere, many dip- horizontal component, twelve types of landform tube phreatic systems are now being modified under unit could be recognised within the three classification vadose conditions. types, giving 36 possible landform unit combinations.The

scheme provides an index of terrain type upon which

be made comparisons can (Day, 1978), and was correlated

Karst bedrock such morphometry against properties, as purity, porosity, pe-

trology and mechanical strength, in order to ascertain the There are karst terrain many quantitative morphometric techniques most influential properties on type. available for karst terrain research, but only a few have Brook & Hanson (1986, 1991) used morphometric been used in research the karst of the on phenomena analysis to assess how successfully karst terrain couldbe

White Limestone The first work Group. published using modelled, to reveal organised patterns in the terrain and the karst morphometric analysis on of Jamaica was that by to assess the potential of morphometry in distinguishing who considered that such Day (1976), an approach pro- karst types. They used double Fourier series analysis to vided the basis for classification a more objective ofkarst uncover significant patterns in the spatial variability of

terrain, while the correlation between form and doline and karst in process, cockpit northern Jamaica, and pro- and the controls on karst also vided correlation databetween landform development, are greatly type, and bedrock aided by a morphometric approach. Specific morphometric structure and lithology. Brook and Hanson measured

of karst terrain the White includes analysis on Limestones fracture trace, depression lengths and orientations in the

that of Brook & Hanson Day (1976), (1986, 1991), Han- Brown’s Town area, parish of St Ann. The data were

son (1985) and et al. while a review of Draper (1998), grouped into ten degree orientation classes and the length used in karst with morphometric techniques studies, weighted values were converted to percentages. The of work from the examples Caribbean as a whole, was dominant directions concurred with the directions of the

presented by MacGillivray (1997). Morphometric analysis more important frequency pairs of the Fourier analysis, of karst the White Limestones on has also been incorpo- while the wavelengths of the frequency pairs coincided rated into Caribbean-wide research, specifically in the with the fracture and depression densities analysed from classification ofkarst terrain types (e.g, Day 1979, 1982). aerial photographs. They concluded that local structures

In a of in the Browns had the formation morphometric study depressions a strong influence on of depressions in

Town area of St used located Ann, Day (1976) randomly the area, there was also a significant difference in the

profiles to measure depth, diameter and internal of related bedrock slope density depressions to two types, which of the from which numberof function angles features, a morpho- was a of folding and faulting. However, the metric ratios The were developed. analysis facilitated a results could not be used to determine the reason for

correlationbetween shape and distributionofthe depres- variance in depression depth in similar bedrock.

sions with factors their It al. influencing morphology. was Draper et (1998) applied a nearest neighbour thought that the the distri- analysis, by quantifying spatial analysis method, used in structural geology to measure butionof dolines, would allow for a inference to preliminary strain, the distributionsof sinks and summits ofpolygo- their as to formation, as collapse might be expected to be nal karst in Cockpit Country. Results showed the distribu- distributed than more randomly solution dolines. How- tion of sinks is essentially random, while that of the concludedthat it infer ever, Day was impossible to from summits is more uniform with nearest neighbour spacings morphometric data alone whether surface of collapse or 125-250 m, with the longer nearest neighbour distribu-

solution the dominant in formation tions was process depression generally trending to the northeast. Draper et al. -214-

that the karst from which in the southern of the vale in the suggested polygonal develops origi- occur part same

distributed nally randomly sinks, and that depression White Limestone facies as the surrounding cockpit karst,

growth ultimately produces uniformly distributed sum- developed on an etch-plain which was uplifted at the end mits. ofthe Pliocene or the beginning of the Quaternary during

a drier climate, as the residual soils associated with the

dolines are not as intensely weathered. The alluvial fans

Landformevolution and gravel terraces seen on the floor of the vale are simi-

larly the product of a drier climate in the Quaternary,

Early publications on the karst of the White Limestones though Landmann (1990) suggested that several phases of interpreted the development of landforms in relationto the alluvial fan formation occurred as a result of humid and

differences between the hard which petrographic pure, crystalline dry cycles, were repeated at least eight times during limestones and the less pure, marly varieties, in that the Quaternary.

and towers tend to the limestones the German school of cockpits occur on pure Thus, according to geomor- and dolines the less limestones on pure (e.g., Sweeting phologists working in Jamaica and the wider Caribbean,

More studies German the of limestone be 1958, 1972). recent by geomor- evolution landforms can explained not phologists have suggested that palaeoclimatic change may only by geological controls, but also by contrasts in the have had influence the an important on development of intensity of karstification during the Tertiary and Quater- karst landforms in Jamaica (Pfeffer, 1986, 1997; Land- nary as a result of palaeoclimatic and palaeoecologic

Pfeffer mann, 1990). (1997) agreed with many ofthe early changes. Some of their interpretations are highly conten- observations of in that dominated tious Sweeting, areas by and speculative, as both the depressions and residual impure or thinly-bedded limestones with interbedded hills, and the weathering products and soils they contain,

doline and that the marly layers always develop karst, cannot be treated as separate landforms; they are both an

massive limestones underlie of residual of the overall of the purer, more areas integral part pitting surface. Their hills with have dolines also cockpits. However, some areas interpretations rely strongly on the premise that the

in bedrock which would cock- bauxites residues of the karstification. developed otherwise show are It is likely that pits and, according to Pfeffer, cannot be explained by geological controls combined with climatic change and

Sweeting’s (1958) interpretation. climate variationshave both had a profound influence on

Pfeffer (1997) argued that the original relief was a the development of karst landforms on the White Lime- peneplain, the main line of evidence for this being the stone Group. Of equal importance to karst evolutionwould similarelevation of the residual limestone hills, and that have been the erosional breaching of the anticlinal struc- this be dated from can the Oligocene-Miocene. The kar- ture and subsequent de-roofing to form the Central Inlier. stification ofthe peneplain in the Miocene-Plioceneled to This exposed non-carbonate rocks and led to the develop- the development of cockpit karst with poljes, and that ment of surface streams which carried large volumes of karstification have been sea-level fall may triggered by or water to the limestones. Subsequent sinking and subterra- local Pfeffer of relief uplift. According to (1969), analysis nean flow through the White Limestones modifiedtheir in southwest Jamaica shows that Tertiary cockpit karst hydrological characteristics from essentially autogenic was uplifted during the Quaternary. Pfeffer (1969, 1997) systems dominatedby vertical percolation routes through also that the bauxites found in the the mixed argued large cockpits limestone, to a allogenic- autogenic system with are the weathering residue of Tertiary relief formation, not only vertical percolation, but also horizontal water and have a higher rate of quartz dissolution and de- movement, forming fairly rapid flow paths. silicification than the red-earth and red loams associated An earliertheory on the evolution of karst landforms with the residual which hills, are considered to be the on the White Limestones also stressed this link to the result of soil formation present and younger karstification. bauxite deposits, where Smith et al. (1972) suggested that,

Pfeffer (1997) suggested this as evidence for higher ‘theorigin of the karst landforms is intimately connected weathering intensities and different morphodynamic with thatof the bauxite deposits’. Smith et al. considered processes during the Miocene-Pliocene which formed that the bauxite originated by the weathering of limestones

the in the from which cockpit karst, compared to Quaternary karstification. cockpits, the weathering residue was which led to a new ‘relief generation’ as a result of a transported via underground drainage to the ‘degraded’ change in palaeoecological conditions. where it was cockpit, deposited by floodwaters, a process Similar of the landform evolution of interpretations which is no longer active. A mathematical model was

Lluidas Vale made Landmann were by (1990), who con- constructed in which they suggested that the White Lime- sidered the oldest reliefunit in the Lluidas Vale area is an stone was first exposed to erosion by uplift in Late Mio- etch-plain which was formedby intense weathering con- cene times and the development ofkarst landforms began

ditions in the The Neogene. etch-plain was subject to with an undulating surface with shallow depressions. In intense karstification the late Miocene late the soil during to model, an incomplete cover then developed in the

Pliocene, which led to the development of cockpit karst depressions leading to differentialrates of dissolution, the and a strongly-weathered residual bauxitic soil. Dolines, latterbeing concentrated beneaththe soil cover. Smith et -215-

al. then contended that more significant slopes develop mation; Mitchell, 2004) is the host of the most extensive due and become to preferential dissolution, as they steeper bauxite deposits, while the Browns Town-Walderston their soil cover is lost by mechanical erosion. Thereafter, Formation (also Moneague Formation) is the principal the become the slopes cease to steeper, as erosion rate is host of bauxite in the north coast belt, with important

the entire of the Smith al. the constant over length slope. et reserves on Troy Formation (Lyew-Ayee & Stewart, assumed in their model that this ‘equilibrium time’ is 1982). The residual theory of the origin of bauxite has reached when the is after which time been slope angle 30°, the questioned and, although the deposits are mainly will retain its slope form. confined to areas underlainby the shallow water carbonate

Smith et al. also incorporated into the mathematical units of the White Limestone Group (Robinson, 1994), the model the development of the cockpit shafts, by supposing relationship ofthese deposits to the bedrock has been the that whilethe slope remains soil all the of numerous covered, drainage subject papers (e.g., Wright, 1977; Lyew- leaves at its base, through fissures in the limestone, lead- Ayee, 1982).

to the formationof shaft. The ofthe shafts Zans also ing a depths are (1958c; see Chubb, 1963) proposed an also controlled the of soil by presence a cover and, once alternative alluvial theory for the origin ofbauxites which this is the shaft and erode removed, slope at the same rate, is closely associated with the groundwater hydrogeology due to the fact that drainage is no longer concentrated of the WhiteLimestone. Zans theorised that alumina-rich down the but into and fissures shafts, seeps directly joints argillaceous debris was eroded from Cretaceous tuffs in in the bare limestone. This, according to Smith et al., the Central Inlier and fluvially transported by surface

for the fact that shafts than 60 accounts are rarely greater streams which sink when flowing onto the White Lime- m deep and the final depth of the shaft will be reached stone. The fine debris continued to be transported by when the reach of 30°. Based surrounding slopes an angle underground drainage, and was carried to the surface and

their mathematical Smith al. maintain that on model, et a deposited by karst waters over the floors of karst depres- shaft of kind will form the base of the sions of various some at slope as a sizes. According to Zans’ theory, the first natural of the of of consequence presence a cockpit. They these muddy sediments were laid down while the island also modelledfinal and radii of and still depths shafts, ‘equi- was being uplifted and continued uplift elevated the librium times’ in relation to cockpit development. The alluvial deposits high above the water table, where lateri- of karst in development degraded relation to bauxite sation converted them to bauxite. In the alluvial theory, also modelled deposits was by Smith et al. (1972) and a uplift accounts for the occurrence of bauxites on the true ‘equilibrium landform’ towards which all slopes in limestone plateau surfaces high above the water table.

will tend It has also been that degraded cockpit was equated. proposed much, if not most, ofthe Smith al. et (1972) attempted to show that their superficial cover ofbauxite is derived from the weathering mathematical model of landform development produced of ashfall deposits produced by volcanic activity in the landform shapes which are not dissimilar to real karst region surrounding Jamaica, especially in the late Ceno- landforms on the White Limestone.Based their on model zoic, some of which are still preserved as ash beds in the of landform evolution, Smith et al. contended that the deep water limestones of the Montpelier Formation equilibrium time for the production of cockpits is about (Comer, 1974, 1976; Comer et al, 1980; Comer & Jack-

0.6 million whilethe total time to years, required produce son, 2004). The ash-fall theory is also supported by other an equilibrium bauxite deposit, or fully degraded karst, is workers (e.g., Lyew-Ayee et al, 1989). Comer (1974)

0.6 million 2.7 million 3.3 million indicated years plus years, or that the relatively high percentage of bentonitic for years an average economic deposit and 3.7 million clay within the Montpelier chalks, the chemical composi- for years a non-economic deposit, similar to the 3.5 mil- tion of the clay (including the highalumina and low silica lion that Smith years (1970) estimated as the time re- contents), and the stratigraphic position above the host

to the total known bauxite limestone all quired produce reserves. suggest that these rocks are the more likely

The times Smith al. for the of material for presented by et (1972) source the bauxites than the parent rocks evolution of both the landforms cockpit are constrained by proposed in the residual theory. According to Comer, the assumptions in the model, not least the generation of timing of volcanic ash deposition coincided with the mean erosion which were constructed of the and much of rates, using water emergence island, so the ash was hardness values and runoffrates using present day data. deposited subaerially and concentrated in pre-existing The model also presupposes that the bauxite deposits karst depressions. Subsequent elevation ofthe ash deposits the originated as insoluble residue of limestone from the and intense leaching of ash and ash-bearing carbonates which is cockpit areas, transported through the subterra- eventually caused the formationof bauxite. Comer con- nean drainage system and deposited by floodwaters to cluded that the exclusive association of bauxite with form of karst. In addition Smith areas degraded to et al. karstified limestonewas related to both the drainage and

(1972), other workers who favoured a residual origin for the dissected nature of the limestones. According to the bauxites include Ahmad al. Hose et (1966), (1963), Comer, the effect of karst development was to trap the

Clarke (1966) and Sinclair 1967, The ash-fall (1966, 1976). parent material in karst depressions which pre- Formation referred the Newport (now to Moneague For- vented erosion, while the high relief topography of the -216-

pre-existing karst resulted in well-drained slopes where Bauxite soils of Jamaica. Soil Science Society of America

719-722. vertical drainage through the limestones provided the Proceedings 30, Aub, C.F. 1964a. Limestone Scenery in Jamaica. Cambridge optimum conditions for the subaerial leaching processes (University of Cambridge)(unpublished MA thesis). required for bauxite formation. Aub, C.F. 1964b. Karst problems in Jamaica, with particular

reference to the cockpit problem. Abstracts, Symposium on

Karst Phenomena, 20th InternationalGeographical Union, Conclusions Seattle, Washington, USA.

Aub, C.F. 1974a. The nature of cockpits and other depressions

This has to review our current under- study attempted in the karst of Jamaica.Proceedings of the 5th International karst ofthe White Lime- standing of the geomorphology Speleological Congress, Stuttgart, 1969,M15/1-7. and ofthe work of stone Group to provide a summary com- Aub, C.F. 1974b. Some observations on the karst morphology

pleted to date. It has also attempted to identify the gaps in Jamaica. Proceedings of the 5th InternationalSpeleological

Congress, Stuttgart, 1969, Ml6/1-7. our knowledge and to indicate areas of future research. A Devine, E.A. & DiTonto, M.A. 1986. Jamaica, the detailed description of each of the main karst landforms Baker, L.L., 1985 expedition of the NSS Jamaica Cockpits Project. Na- occurring on the White Limestone Group has been pre- tionalSpeleological Society News 44 (1), 4-15. sented. The most extensive karst landform type is cockpit small- Barker, D. & Miller, D.J. 1995. Farming on the fringe: also karst, followed by doline and tower karst. Poljes are scale agriculture on the edge of Cockpit Country. In: Barker, have important landform elements and most a strong D, & McGregor, D.F.M. (eds). Environmentand Develop- structural control, being closely related to block faulting. ment in the Caribbean: Geographical Perspectives, 271-292. in Both lithological and structural controls are important Kingston (The Press, University ofthe West Indies). the of karst landforms within the White of Jamaica. development Beche, H.T. de la 1827. Remarks on the geology ofthe Central inlier Limestone Group, and the de-roofing Transactions ofthe Geological Society London (2) 2, 143-

fundamentally altered the karst hydrology of the 194.

The of limestones and greatly modified the overall karst land- Brook, G.A. & Ford, D.C. 1978. origin labyrinth and

Climatic also have had tower karst and the climatic conditions necessary for their scape. change may a profound development. Nature 275, 493-496. influence on karst development of the White Limestone Brook, G.A. & Hanson, M. 1986. Quantitative analysis of it be that karst Group, as may argued some phenomena are depression morphology near Brown’s Town, Jamaica and essentially hydrologically relic and represent karstification bedrock factors influencing cockpit or doline development. during wetter periods than experienced at present, specifi- Proceedings of the 9th International Speleological Con- the vertical shafts associated with cockpit karst. cally 124-127. gress, Spain 1, Detailed mapping of the karst has geomorphological Brook, G.A. & Hanson, M. 1991. Double Fourier series analysis and been restricted to a few small localities more system- Jamaica. of cockpit and doline karst near Brown’s Town, of the White Limestone atic mapping of the karst Group Physical Geography 12, 37-54. few needs to be undertaken. In addition, only a morpho- Brown, M.C. & Ford, D.C. 1973. Caves and groundwater

metric studies of the karst have been undertaken in Ja- patterns in a tropical karst environment, Jamaica, West In-

dies. Journal Science 622-633. maica, and these have been limitedto small isolated areas American of 273, Canter, R. 1987. Cockpits and pits. National Speleological of karst for quantitative analysis and classification of the Society News 45, 53. landforms. A combinationofgeomorphological mapping Chenoweth, M.S. & Day, M.J. 2001. Developing a GIS for the and a more systematic morphometric analysis of the karst Jamaican Cockpit Country. In: Geotechnical and Environ- and under- would greatly increase our knowledge base mentalApplications ofKarst Geology and Hydrology, Pro- the White Limestone standing ofthe karst landscapes on ceedings of the 8th Multidisciplinary Conference On Sink- Group. holes and the Engineering and Environmental Impacts of

Karsts, Louisville, Kentucky, 1-4 April. Balkema (Lisse). Chubb, L.J. 1963. Bauxite genesis in Jamaica.Economic Geol-

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Clarke, O.M. Jr. 1966. The formationof bauxite on karst topog-

West Indies. Many thanks to Dr Simon F. Mitchell for his help in raphy in Eufaula district, Alabama and Jamaica,

Leonard Notice who Economic Geology 61, 903-916. compiling Figure 1, and to Mr com- Comer, J.B. 1974. Genesis of Jamaican bauxite. Economic pleted the remaining figures and scanned the photographs. Geology 69, 1251-1264. I thank Mick Day and Donald McFarlane for their con- Comer, J.B. 1976. Genesis of Jamaican bauxite - a reply. Eco- structive review comments. nomic Geology 71, 822-823.

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