the forest was predominantly formed by oak and beech, though second growth in the lower slopes has favoured the aggressively re-seeding spanish chestnut. a relict stand of beech, rare in central italy, remains on the upper slopes of monte cimino. sub-fossil pollen analyses from cores of stratified sediment taken in the region's crater lakes typically reveal a pollen sequence characteristic of tundra lying over an all-but-sterile wind-blown loess sand; this in turn was followed by grassland, with pollen of water-lilies and pondweeds blown from glacial meltwater lakes. the earliest holocene forest was fir, followed by mixed pine and oak, with a climax forest of beech and oak, including "quercus ilex".