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Long Pond Sinkhole

July 21, 2010

District: Clarks Town

Parish: Trelawny

WGS84 L/L: 18 25 51.2, 77 32 43.5

JAD2001: 692378 E, 697777 N

JAD69: 192267 E, 197488 N

Altitude: 185m WGS84

Accuracy: +/- 5m horizontal; +/- 10m vertical


Type: Impenetrable sink

Accessibility: SCUBA

Depth: Unknown

Length: Unknown

Explorers: Stewart - 2010

Survey: Stewart - Sketch

JU Ref: N/A

JU Map: N/A

Entrance size: ~40m W

Entrance aspect: Zenith

Vegetation in general locale: Sugar cane

Vegetation at entrance: Sugar cane

Geology: White limestone/Alluvial

Bedding: Unknown

Jointing: Unknown

Speleothems: None

Palaeo resources: None

Archaeo resources: None

Hydrology: Wet

Dark zone: Unknown

Climate: N/A

Bats: None

Bat guano: None

Guano mining: N/A

Guano condition: N/A

Visitation: N/A

Speleothem damage: N/A

Graffiti: N/A

Trash: Refinery waste

Ownership: Private (Everglades)

Protection: None

Vulnerability: High.

Long Pond Sinkhole
July 21, 2010
Notes: RS Stewart

Long Pond Sinkhole was visited on July 21, 2010, in assistance to a government agency that shall remain unnamed. Location information was vague, so the primary purpose of the visit was to simply find it, and record accurate coordinates. However, evidence of input from the Long Pond sugar refinery was also noted.

The site was unlisted before the visit, and we have no information regarding its original state. The geomorphology suggests that it held pooled water at the same level as the local, seasonal water table.

At the time of the visit, the sinkhole held standing water at a level slightly lower (~50cm) than the lowest area immediately external. The pool was roughly circular, about 40m wide, with a dirt berm on the west side, and a trench at the southwest corner that carried water from the direction of the Long Pond factory.

To the north and east of the sinkhole is a limestone hill, and to the south and west is alluvium. The lowest surface area is on the west, at the berm.

The berm is about 1.5m high, and 2.5m wide, and appears to have been constructed within the last two years. Evidence for this is the relative lack of vegetation, other than the invasive Castor plant, with the plants less than one year old (<2m high). Shorter (<1m), dead plants of the same species were also present in smaller numbers, and all appeared to have been dead for about the same amount of time, estimated to be within one year.

The trench also appears to be of relatively recent construction. It is 1.5-2m wide, is dug through about 2m of alluvial soil until water level is reached, and has vertical sides. No slumping was seen.

The water in the sinkhole was highly pigmented, the colour a deep reddish-brown. It did not look like silt, or other particulates, but rather some substance in solution.

Regarding water levels in the hole: The berm was cut with a shallow run-off trench, this about 80cm deep and 1m wide, which appears to have periodically carried overflow water into a field to the west. It was dry at the time of the visit, but there was a thin layer of sediment in both the trench and to the west. This suggests that the water level rose higher in the recent past, and as it began to overtop the solid berm, a small run-off trench was cut to prevent the entire berm from washing away. The only input seen was from the factory trench.

N.B. The visit was carried out alone by RS Stewart (who felt a little like Jack Nicholson in Chinatown as he did it), and he takes sole responsibility for not having obtained permission beforehand from Everglades Farms Limited.

Long Pond Topo sketch map

Click for full size

Position on 50k Topo - Click image for full size
JGW referencing file in JAD2001 for the full resolution version of the above map

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Position on 6m DEM - Click image for full size
JGW referencing file in JAD2001 for the full resolution version of the above map

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