Meb Cutlack
The Reporter (Belize)
April 5, 2001

The prospect of undetected underground limestone caverns diverting water from the proposed Chalillo dam has come to light by one of Belize’s most experience geologists.

“Concerning the geology of the Raspaculo basin I can offer the following comments”, Brian Holland (Managing Director of Belize Minerals), wrote, “The oldest rocks in the Raspaculo River basin are composed of Carboniferous to Permian sedimentary rocks. These include shales, sandstones and limestones. Along the Raspaculo River near the confluence of the Macal River, there are crinoidal limestones of Permian age exposed along the banks (see e.g. Dixon, page 20). Dixon states that this limestone reaches a thickness 50 feet in this area, but thickens southwards towards Little Quartz Ridge to 100 feet. Bateson & Hall (1977, page 8), however, proved the existence of many more crinoidal limestone sequences in the area and therefore the total thickness is much greater than reported by Dixon. Apart from the limestones, the riverbed in this area exposes sandstones and conglomerates with subordinate shales. I did not see any granite nor have any been reported in this area by Dixon or Bateson & Hall”.

His letter went on: “I had the good fortune to take part in the JESSEUR expedition a few years ago and walked up the Raspaculo River from Rubber camp nearly to the headwaters of the river. A distance of about 38 kilometers. I can confirm Dixon’s report on the limestone. I often saw tufa deposits along the banks of the Raspaculo River east of the confluence with the Macal River. Tufa deposits are formed by the redeposition of limestone (calcium carbonate). These tufa deposits are most likely derived from the solution of the Permian crinoidal limestone. Consequently, there must be solution features (e.g. caves) in this limestone above the riverbank”.

His letter added: “In addition to the Permian limestones there are thick sequences of Cretaceous limestones that occur on top of the Carboniferous-Permian rocks on both sides of the Raspaculo River south of the confluence with the Macal River. These are neatly illustrated by Bateson & Hall’s (1977) geological map of the Maya Mountains. The Cretaceous limestones east of the Raspaculo River form a “block measuring 10 km by 10 km north of the confluence with the Monkey Tail Branch. The center of this “block” is cut by an east-west trending fault. South of the confluence there is another large “block” of Cretaceous limestone. West of the river the Cretaceous limestone forms a thick section of the surface bedrock and extends from an area just south of Guacamallo Bridge to the Toledo District. This Cretaceous limestone sequence contains the world’s fifth largest systems of caves (see the Journal of Cave and Karst Research).

Earlier, in searching the Belmopan archives for a report on Hydro Power done by Charles Wright in the late 50’s, I unearthed a sketch of the area made by Brian Holland in 1993.(see illustration) This sketch is strikingly similar to a diagram drawn for me by Charles Wright in 1997.

Mr. Hollands statement: “West of the river the Cretaceous limestone forms an area just south of Guacalollo Bridge to the Toledo District” also confirms what Charles Wright told me in 1997; that the water from a hydro dam or reservoir in the Raspaculo Macal area could, via a fisure into underground caverns, disappear into Guatemala or Toledo!