| Middle Berounian alternating shale & sandstone beds, Collado de la Plata massif | Dobrotiviense | Bronchales | Castilla-La Mancha |
| Middle Mbr, Armorican Quartzite Fm., Celtiberia, Zaragoza, Spain | Arenig | Armorican Quartzite | Aragón |
| Millers Tortosa | Oxfordiense | — | Cataluña |
| Mina Esquirol-1 | Maastrichtiense inferior | Grey Garumnian | Cataluña |
| Mina Esquirol-2 | Maastrichtiense inferior | Grey Garumnian | Cataluña |
| Mina Esquirol-3 | Maastrichtiense inferior | Grey Garumnian | Cataluña |
| Mina Valero, Buñol | Titoniense | Higueruelas | Comunitat Valenciana |
| Mina Victoria tracksite | Berriasiense superior | — | — |
| Minas de azufre de Libros | MN 9 | — | Aragón |
| Minas de Libros | MN 9 | — | Aragón |
| Minas Tierga-1 (MT1), level 18, Mesones Unit | Piso 3 | Ribota | — |
| Minas Tierga-1 (MT1), level 33, Mesones Unit | Piso 3 | Daroca | — |
| Minas-Tierga 1 (MT1) and Minas Tierga-3 (MT3) sections, Mesones Unit | Piso 4 | Huérmeda | — |
| Minorca Fossil Rodents | Mioceno superior | — | — |
| Mirador de la Trava | Wordiense | Unidad Roja Superior | — |
| Mirador de Vallcebre | Maastrichtiense superior | Conques | — |
| Miraflores I tracksite | Berriasiense | Huérteles | — |
| Mirambueno 1 | Oligoceno superior | Alcorisa | Aragón |
| Mirambueno 2A | Oligoceno superior | Alcorisa | Aragón |
| Mirambueno 4B | Oligoceno superior | Alcorisa | Aragón |
| Mirambueno 4C | Oligoceno superior | Alcorisa | Aragón |
| Mirambueno 4D | Oligoceno superior | Alcorisa | Aragón |
| Mirantes de Luna | Givetiense | Portilla | Castilla y León |
| Miravete 1 tracksite | Kimmeridgiense | Villar del Arzobispo | Aragón |
| Miravete 2 tracksite | Hauteriviense superior | El Castellar | Aragón |
| MJE-E-30, Montejícar area, Subbetic | Bajociense | Camarena | — |
| MJE-E-38b, Montejícar area, Subbetic | Bajociense | Camarena | — |
| MJN-1-base, Montejícar area, Subbetic | Bathoniense | Jarropa Radiolarite | — |
| MJW-E-13, Montejícar area, Subbetic | Bajociense | Camarena | — |
| MJW-E-21, Montejícar area, Subbetic | Bajociense | Camarena | — |
| MJW-E-55c, Montejícar area, Subbetic | Bathoniense | Jarropa Radiolarite | — |
| MJW-E-72, Montejícar area, Subbetic | Bathoniense | Jarropa Radiolarite | — |
| MJW-F-base, Montejícar area, Subbetic | Kimmeridgiense | Milanos | — |
| MMSa 5A, Mola Murada section | Aptiense inferior | Forcall | — |
| MMSa 6, Mola Murada section | Aptiense inferior | Forcall | — |
| MMSa4, Mola Murada section | Aptiense inferior | Forcall | — |
| MMSa5, Mola Murada section | Aptiense inferior | Forcall | — |
| Moguer-A | Zancliense | Arenas de Huelva | Andalucía |
| Moja | Burdigaliense | — | — |
| Mola de Xert, lagoon facies of upper shallow platform, Maestrat Basin, Castellon | Aptiense inferior | Villarroya | — |
| Mola Hill | Zona Margaritatus | — | Comunitat Valenciana |
| Mola Murada section (Tolós Lládser collection) | Aptiense inferior | Forcall | — |
| Mola Murada, Maestrat Basin | Aptiense inferior | Forcall | — |
| Moleta Cave, E150-250 | Pleistoceno superior | — | — |
| Moleta Cave, X200 | Pleistoceno superior | — | — |
| Moli del Baró-1 | Maastrichtiense superior | Talarn | Cataluña |
| Moli del Baró-2 | Maastrichtiense superior | Conques | Cataluña |
| Molino Alto 1 | Hauteriviense superior | El Castellar | Aragón |
| Molino Bajo. 8 meters | Berouniense | Fombuena | Aragón |
| Molino Bajo. 9 meters | Berouniense | Fombuena | Aragón |
| Molino Fmn, Cordillera Iberica Oriental | Emsiense superior | Molino | Aragón |
| Mollusca, Siera de Valdancha, Traiguera | Albiense superior | Lignites de Traiguera | — |
| Monachil section, reef framework | Tortoniense | — | Andalucía |
| Monachil section, reef-slope subunit | Tortoniense | — | Andalucía |
| Moneva village, Sot de Chera Fm, sample 32/1 | Oxfordiense superior | Sot de Chera | — |
| Moneva village, Sot de Chera Fm, sample 32/2 | Oxfordiense superior | Sot de Chera | — |
| Moneva village, Sot de Chera Fm, sample 32/3 | Oxfordiense superior | Sot de Chera | — |
| Moneva village, Sot de Chera Fm, sample 32/4 | Oxfordiense superior | Sot de Chera | — |
| Moneva village, Sot de Chera Fm, sample 32/5 | Kimmeridgiense inferior | Sot de Chera | — |
| Moneva village, Sot de Chera Fm, sample 32/6 | Oxfordiense superior | Sot de Chera | — |