Table 1.

Types of stones comprising the mega-stones of Menga dolmen.

Type	Classification of limestones basad on the scheme of Folk50	Grain size (mm)	Mineralogical composition	Skeletal grains	Non-skeletal grains	Matrix	Texture classifications (Dunham51)	Microstructure and sedimentary structure	Sediment supply	Paleoenvironment
1	Bioclastic calcirudite	> 2	70–80% calcite, 25–18% quartz, limestone, iron oxides, feldspar and glauconite 5–2%	Main components: Bryozoans, bivalves (Clamys, pectinid) Other components: echinoids, coralline corals, benthic foraminifers (amphisteginas, globigerinas), brachiopods, balanids	Intraclasts (limestone) pellets	Low sparite and absence of micrite	Rudstone	Syndepositional intergranular voids, parallel-laminated	Factory zone	Submarine canyon
2	Bioclastic calcarenite	< 2	70–80% calcite, 25–18% quartz, limestone, iron oxides, feldspar and glauconite 5–2%	Main components: Coralline algae Other components: nodular and branching bryozoans, bivalves, solitary corals, echinoderm spines	Pellets	Contains carbonate mud	Packstone-rudstone, crusts are bindstones	Syndepositional intergranular voids, parallel-laminated	Factory zone	Submarine canyon
3	Bioclastic calcirudite/micro-breccia	> 2	70–80% calcite, 25–18% quartz, limestone, iron oxides, feldspar and glauconite 5–2%	Bivalves (pectinid), bryozoans, coralline algae	Pellets	Contains carbonate mud	Rudstone	Syndepositional intergranular voids, parallel-laminated	Factory zone	Submarine canyon
4	Calcareous breccia	> 2	70% calcite, 15% quartz, 8% feldspar, iron oxides (oncolites), sandstone and flint 2%. To a lesser extent: filositicates, slates, coal	Bivalves (pectinid), bryozoans, coralline algae	Dolomite, oolitic limestones, marly limestones	Contains carbonate mud	Rudstone	Synsedimentary cement, low-angle, parallel-laminated, overlapping edges	River	Submarine canyon
5	Bioclastical calcarenite	< 2	70–80% calcite, 25–18% quartz, iron oxides, feldspar and glauconite 5–2%	Bivalves (Clamys, pectinid), brachiopods, echinoderm spines bryozoans, echinoides	Pellets	Low sparite and absence of micrite	Rudstone	Syndepositional intergranular voids, low-angles, parallel-laminated, burrows		Foreshore (Beach)

Based on the classification of Dunhan⁵¹ for carbonate rocks and Folk⁵⁰. Modified from Lozano Rodríguez et al.²⁵.