Lake Montcortès and Its Surroundings

Lake Montcortès is one of the few lakes with annually laminated (varved) sediments documented in the Mediterranean region. This small (400–500 m diameter) and deep (32 m) kidney-shaped carstic lake is situated on the Iberian side of the central Pyrenees at 1027 m elevation under a seasonal temperate montane climate with Mediterranean influence. The annual average temperature is 9.7 °C, with winter minima of 2.0 °C and summer maxima of 19.0 °C. The total annual precipitation averages 1031 mm, with maxima in spring (110 mm) and autumn (90 mm) and minima in summer (70 mm) and winter (58 mm). The regional vegetation is a mosaic of three main forest types—evergreen Mediterranean sclerophyll forests dominated by Quercus rotundifolia, and deciduous submontane forests dominated by Q. pubescens/Q. subpyrenaica, and conifer montane forests dominated by Pinus nigra—intermingled with shrublands, meadows, grasslands, herbaceous crops, and badlands. A fringe of well-developed and diverse aquatic vegetation dominated by grasses and sedges grows on the lake shores. Limnologically, Lake Montcortès shows meromictic/monomictic behavior, which favors the formation and preservation of seasonal laminations of the biogenic/endogenic type, with alternating light (calcite) and dark (organic) layers. The Montcortès laminated sequence is unique across the Mediterranean region, as it is continuous and absolutely dated, encompassing at least the last 3000 years.