Paleoclimatic Variation in the Valley of Guatemala during Precolumbian Times

Core samples removed from Lake Amatitlán (13-15 March, 2000)

Personnel: Dr. Mark Brenner, Dr. Jason Curtis, Lic. Erick Ponciano, Dr. Guillermo Mata, Ing. Federico Gularte Hernández (AMSA), Ing. Juan Fernando Valladares Morales (AMSA), Carlos M. Vega (AMSA), Jaime Adolfo Estrada (AMSA), Arturo Olivares (AMSA). (The initials AMSA indicate that these people work for the management of Lake Amatitlán (Autoridad para el Manejo Sustentable de la cuenca y del lago Amatitlán).)

The main equipment used for lake coring was brought from the U.S. by Drs. Brenner and Curtis; appropriate tubing, rope and other necessary materials were purchased in Guatemala (Figure 4). A boat was loaned by the Friends of Amatitlán through the help of Dr. Guillermo Mata, who also provided information and a map showing the depths at closely spaced intervals around the lake. Three stations were selected as appropriate for coring (for details see Appendix. For locations of the stations, see Figure 5).

Drs. Brenner and Curtis began the sampling on March 13, continuing over the next two days. Sediment/water interface cores were extruded and sampled at 4 cm intervals into a tray attached to the top of the core barrel. The sediment was transferred to labeled Whirl-pak bags, then placed in Zip-lock bags and stored in a Rubbermaid container. A description of the coring follows (also see Appendix).

Station 1 (site 13-III-2000 on Figure 5) was established in the bay just to the north of the railroad crossing that separates the lake into two basins. Water depth at this site was 13.0 m;. GPS coordinates were N 14°27°23.3" and W 90°33°57.8".  Seven drives were completed, ultimately reaching a depth of 475 cm below the sediment/water interface.

Station 2 (site 14-III-2000 on Figure 5) was in the bay in the southeastern area of the lake (southern basin). Water depth was 11.05 m; GPS measurements were N 14°26°45.5" and W 90°31°53.7".  A total of eight drives were accomplished, obtaining samples down to a depth of 544 cm.

Station 3 (site 14-III on Figure 5) was in the northwest area of the lake (northern basin). Water depth was about 13.6 m; GPS measurements were N 14°28°27.1" and W 90°36°17.5".  At this station nine drives were made, obtaining samples down to a depth of 701 cm.

All core material was subsequently transferred to the University of Florida Department of Fisheries and Aquatic Sciences where it was stored in a cooler kept at 4°C.

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