5) 2-3 cm darker brownish and slightly carbonaceous rock
, with abundant brachiopod shells and fragments in the upper part.
Roughly two-thirds of Cuba's territory is karstic, with an abundance of limestone, marlstone, marble and other carbonaceous rocks
Metasedimentary rocks are represented by phyllites, siltstones, carbonaceous rocks
, sandstones, grits and conglomerates.
Finer material is also derived from the downfall of finely laminated clayey carbonaceous rocks
Usually the content of crystalline rocks in the gravel-pebble fraction of glaciofluvial deposits is 10-15% higher than in tills, whereas the content of carbonaceous rocks
in them is correspondingly lower (Raukas 1978).