| M-Ord section, Sierra Morena, Badajoz, Spain | Dobrotiviense | — | Extremadura |
| M-Ord section, Sierra Morena, Caceres, Spain | Oretaniense | — | Extremadura |
| M-Ord section, Valancia de Alcantara, Caceres, Spain | Dobrotiviense | — | Extremadura |
| Macrofauna, Los Valles de Fuentiduenya (Segovia) | Vallesiense | — | Castilla y León |
| Madalenas | Pleistoceno superior | — | — |
| Maestrazgo, Spain | Hauteriviense inferior | — | Aragón |
| Magret | Maastrichtiense inferior | Conques | Cataluña |
| Mahou | Mioceno medio | — | Comunidad de Madrid |
| Majolicas | Pleistoceno medio | — | Andalucía |
| Malaguide Complex, Casa de la Sabina locality | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, SAB01a Sample | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, SAB01b Sample | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB01c | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB01d | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB01e | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB02a | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB03a | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB03b | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB03c | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB04a | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB04b | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB04c | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB04d | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB04e | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB05a | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB05b | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB05c | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB05d | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB05e | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB05f | Rupeliense | El Bosque | — |
| Malaguide Complex, Casa de la Sabina locality, sample SAB06a | Rupeliense | El Bosque | — |
| Mallorca | Plioceno inferior | — | — |
| Mallorca Buntsandstein tracksite (lower) | Triásico inferior | — | Illes Balears |
| Mallorca Buntsandstein tracksite (upper) | Buntsandstein | — | Illes Balears |
| Manchones | Mioceno | — | Aragón |
| Manzanares River terrace, near Madrid | Pleistoceno medio | — | Comunidad de Madrid |
| Marbella, bindstones | Serpujoviense | Marbella | Andalucía |
| Mariposas Fmn, submember d4a-alpha, Nogueras area, Aragon, Spain | Praguiense | Mariposas | Aragón |
| Mariposas Fmn, submember d4a-beta, Nogueras area | Emsiense inferior | Mariposas | Aragón |
| Mariposas Fmn, submember d4a-gamma, Nogueras area, Aragon, Spain | Emsiense inferior | Mariposas | Aragón |
| Mariposas Fmn, submember d4b-alpha, Nogueras area, Aragon, Spain | Emsiense inferior | Mariposas | Aragón |
| Mariposas Fmn, submember d4b-beta (upper cephalopod Lst), Nogueras area, Aragon | Emsiense superior | Mariposas | Aragón |
| Mariposas Fmn, submember d4b-beta, Nogueras area, Aragon, Spain | Emsiense superior | Mariposas | Aragón |
| Mariposas Fmn, submember d4b-delta, Nogueras area, Aragon, Spain | Emsiense superior | Mariposas | Aragón |
| Mariposas Fmn, submember d4b-gamma, Nogueras area, Aragon, Spain | Emsiense superior | Mariposas | Aragón |
| Marizulo | Pleistoceno superior | — | — |
| María Isabel Quarry | Estefaniense B | Puertollano basin | — |
| Mas de Artis | Aptiense | — | Cataluña |
| Mas de Curolles-1 | Hauteriviense superior | — | Comunitat Valenciana |
| Mas de Curolles-II | Barremiense inferior | Mirambel | — |
| Mas de Eroles (0.0 m) | Aptiense inferior | Capas Rojas | Comunitat Valenciana |
| Mas de Eroles (2.8 m) | Aptiense inferior | Capas Rojas | Comunitat Valenciana |
| Mas de la Chimenea Alta (2.0 m) | Barremiense superior | Arcillas de Morella | Comunitat Valenciana |
| Mas de la Chimenea Alta (level 11) | Barremiense superior | Arcillas de Morella | Comunitat Valenciana |
| Mas de la Chimenea Alta (level 16) | Barremiense superior | Arcillas de Morella | Comunitat Valenciana |
| Mas de Morull tracksite | Maastrichtiense superior | Figuerola | Cataluña |
| Mas de Noto | Cretácico superior | — | Comunitat Valenciana |
| Mas de Palau 1a | Barremiense | Arcillas de Morella | — |
| Mas de Palau 1b | Barremiense | Arcillas de Morella | — |
| Mas de Palau 2 | Barremiense | Arcillas de Morella | — |
| Mas de Palau 3 | Barremiense | Arcillas de Morella | — |
| Mas de Peteix | Barremiense superior | Arcillas de Morella | Comunitat Valenciana |
| Mas de Rafael | Barremiense superior | Arcillas de Morella | Comunitat Valenciana |
| Mas de Sabater, Cantera del Mas de la Parreta | Aptiense inferior | Arcillas de Morella | Comunitat Valenciana |
| Mas del Dolço | Barremiense superior | Arcillas de Morella | Comunitat Valenciana |
| Mas Guimera (0.0 m) | Barremiense superior | Arcillas de Morella | Comunitat Valenciana |
| Mas Guimera (general) | Barremiense superior | Arcillas de Morella | Comunitat Valenciana |
| Mas Macià Querol | Aptiense inferior | Capas Rojas | Comunitat Valenciana |
| Mas Romeu (0.0 m) | Barremiense superior | Arcillas de Morella | Comunitat Valenciana |
| Mas Romeu (11.8 m) | Barremiense superior | Arcillas de Morella | Comunitat Valenciana |
| Mas Romeu Veil | Luteciense | — | — |
| Mas Vilageliu | Bartoniense | Vic-Manlleu | — |
| Masada del Chato 2 | Barremiense inferior | Mirambel | Aragón |
| Masada del Valle 2 | Turoliense | Alfambra | Aragón |
| Masada del Valle 3 | Turoliense | Alfambra | Aragón |
| Masada del Valle 4 | Turoliense | Alfambra | Aragón |
| Masada del Valle 5 | Turoliense | Alfambra | Aragón |
| Masada del Valle 6 | Turoliense | Alfambra | Aragón |
| Masada del Valle 7 | Turoliense | Alfambra | Aragón |
| Masegosa | Barremiense superior | El Collado | Castilla-La Mancha |
| Masia de l'Hereuet | Ypresiense | Corca | Cataluña |
| Masia de La Roma | Vallesiense | — | Aragón |
| Masia de Ramón [Conques Fm.] | Maastrichtiense inferior | Conques | Cataluña |
| Masia de Ramón [Talarn Fm.] | Maastrichtiense superior | Talarn | — |
| Masia de Ramón-Mas d'en Feliu tracksite | Maastrichtiense inferior | Conques | Cataluña |
| Masia del Barbo 2A | Vallesiense | Alfambra | Aragón |
| Masia del Barbo 2B | Vallesiense | Alfambra | Aragón |
| Masos de Pals section, Emporda area | Luteciense | Banyoles Marl | — |
| Masía dela Hoya Alta, Formiche Alto (FA-5) | Kimmeridgiense | Villar del Arzobispo | — |
| Matallana (de Torio), MT | Givetiense | Portilla | Castilla y León |
| Matamoros 4B | MP 21 | Villarrosano | Aragón |
| Maya de Baztan | Emsiense superior | Arizacun Ls | — |
| Mazaterón | Bartoniense | Mazaterón | Castilla y León |
| Medas Islands | Pleistoceno inferior | — | Cataluña |
| Member #2, Najerilla Formation, Logrono, Spain - Shergold et. al. 1983 | Franconiense | Najerilla | La Rioja |
| Membrillar, Estena River | Ediacárico | Villarta | — |
| Meré, southwest of Llanes | Marsdeniense | Ricacabiello | Principado de Asturias |
| Mesetas de Con | Estefaniense C | — | Principado de Asturias |
| Mesones village | Toyoniense | Valdemiedes | — |
| Mesones-9 section (M9, Mesones de Isuela) section, Mesones Unit | Piso 4 | Huérmeda | — |
| Mestas de Con, Cangas de Onis, Asturias | Pleistoceno inferior | — | Principado de Asturias |
| Micrites with Pseudotriloculina, Discorbis | Santoniense superior | — | — |
| 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 | — |
| Monforte Fmn, unit 1, Cordillera Iberica Oriental | Eifeliense | Monforte | Aragón |
| Monforte Fmn, unit 2, Cordillera Iberica Oriental | Eifeliense | Monforte | Aragón |
| Monforte Fmn, unit 4, Cordillera Iberica Oriental | Eifeliense | Monforte | Aragón |
| Monforte Fmn, unit 6, Cordillera Iberica Oriental | Eifeliense | Monforte | Aragón |
| Moniello - Mon-01 & 02 | Emsiense | Moniello | — |
| Moniello - Mon-12 | Emsiense | Moniello | — |
| Moniello - Mon-13 | Emsiense | Moniello | — |
| Moniello - Mon-14 | Emsiense | Moniello | — |
| Moniello, Arnao Section fenestrate bryozoan | Eifeliense | Moniello | — |
| Moniello, Moniello Formation, Lower Moniello Beds, Asturias | Emsiense superior | Moniello | — |
| Monistrol de Noya, Penedes Valley, Catalonia | Burdigaliense | — | — |
| Montalbán 10 | Oligoceno inferior | — | Aragón |
| Montalbán 11 | Oligoceno inferior | — | Aragón |
| Montalbán 12 | Oligoceno inferior | — | Aragón |
| Montalbán 1D | Oligoceno inferior | — | Aragón |
| Montalbán 3C | Oligoceno inferior | — | Aragón |
| Montalbán 3X | Oligoceno inferior | — | Aragón |
| Montalbán 7 | Oligoceno inferior | — | Aragón |
| Montalbán 8 | Oligoceno inferior | — | Aragón |
| Montalbán 9 | Oligoceno inferior | — | Aragón |
| Montalbán S | Oligoceno inferior | — | Aragón |
| Monte Orobe, near Alsasua (MGSB collection) | Albiense superior | — | — |
| Monte Orobe, near Alsasua (Ruiz de Gaona collection) | Albiense superior | — | — |
| Monte Pila 1 | Burdigaliense | Transitional facies between the Najera and Haro | — |
| Monte Pila 2 | Burdigaliense | Transitional facies between the Najera and Haro | — |
| Monte Pila 3 | Burdigaliense | Transitional facies between the Najera and Haro | — |
| Monte Puente Ballesta site, Salas de los Infantes | Hauteriviense superior | Pinilla de los Moros | Castilla y León |
| Montes de Toledo | Ediacárico | Pusa Shale | — |
| Montfalcó, bed 1 | Zona Ibex | Escales | — |
| Montfalcó, bed 4 | Zona Spinatum | Barre a Pecten | — |
| Montfalcó, bed 6 | Zona Tenuicostatum | Padrinas | — |
| Montfalcó, bed 7 | Zona Bifrons | Padrinas | — |
| Montjuic | Burdigaliense | — | — |
| Montjuic (Eocene) | Luteciense | — | Cataluña |
| Montoria, Alava | Calloviense | — | País Vasco |
| Montoria, Alava | Oxfordiense | — | País Vasco |
| Montral and Alcover Quarries (MA) | Ladiniense | Muschelkalk | — |
| Montral and Alcover Quarries (MSB) | Ladiniense | Muschelkalk | — |
| Montral, Tarragona, Dasycladacean reef, Cataluna | Ladiniense | — | Cataluña |
| Montral-Alcover quarries | Longobardiense | Muschelkalk | Cataluña |
| Montrebey | Maastrichtiense inferior | La Posa | Cataluña |
| Montsec area | Cenomaniense | — | Cantabria |
| Montsec area | Turoniense | — | Cantabria |
| Montsec area | Coniaciense | — | Cantabria |
| Montsec area | Santoniense superior | — | Cantabria |
| Montsec area | Campaniense superior | — | Cantabria |
| Montsech de Ager | Santoniense | — | Cataluña |
| Moraig Cave | Albiense superior | — | — |
| Moratilla 3 (MOR3) | Mioceno inferior | — | Aragón |
| Moratines | Orleaniense | — | Comunidad de Madrid |
| Moreda 1, stage 1 | Rusciniense | — | Andalucía |
| Moreda 1, stage 2 | Rusciniense | — | Andalucía |
| Moreda 1L, stage 1 | Rusciniense | — | Andalucía |
| Moreda 1L, stage 2 | Rusciniense | — | Andalucía |
| Morella | Barremiense superior | Arcillas de Morella | Comunitat Valenciana |
| Morella Sub-basin-1 | Barremiense superior | — | Comunitat Valenciana |
| Morgades, Artiga, Penedes Valley, Catalonia | Burdigaliense | — | — |
| Moro | Maastrichtiense inferior | Arén | Cataluña |
| Moror-A tracksite | Maastrichtiense inferior | Arén | Cataluña |
| Moror-B tracksite | Maastrichtiense inferior | Arén | Cataluña |
| Moscardón tracksite, 1MSC | Kimmeridgiense | Villar del Arzobispo | — |
| Moyuela Fmn, lower third, Cordillera Iberica Oriental | Eifeliense | Moyuela | Aragón |
| Moyuela Fmn, middle third, Cordillera Iberica Oriental | Eifeliense | Moyuela | Aragón |
| Moyuela Fmn, upper third, Cordillera Iberica Oriental | Eifeliense | Moyuela | Aragón |
| MR-8 tracksite, Mora de Rubielos | Hauteriviense superior | El Castellar | — |
| MRSa 1, Mola Rodona section | Aptiense inferior | Forcall | — |
| MRSa 2, Mola Rodona section | Aptiense inferior | Forcall | — |
| MRSa 3, Mola Rodona section | Aptiense inferior | Forcall | — |
| MRSa 4, Mola Rodona section | Aptiense inferior | Forcall | — |
| Muela de Miro, Morella | Aptiense superior | — | Comunitat Valenciana |
| Muniesa, Teruel | Barremiense inferior | Blesa | Aragón |
| Munilla Nivel 4 tracksite | Barremiense | — | La Rioja |
| Munter, Vic area, La Guixa Member, Ebro Basin, Catalonia | Bartoniense | Vic Marls | — |
| Murchas town | Mioceno medio | — | Andalucía |
| Murchas, mammal locality | Mioceno medio | — | Andalucía |
| Murero [Murero Fm] | St Davids | Murero | Aragón |
| Murero Formation | Drumiense | Murero | — |
| Muro | Burdigaliense | — | Illes Balears |
| Muro de Aguas, outcrop A | Hauteriviense | — | La Rioja |
| Muro de Aguas, outcrop B | Hauteriviense | — | La Rioja |
| MV-1, Miravete de la Sierra | Barremiense superior | Arcillas de Morella | — |
| MV-2, Miravete de la Sierra | Barremiense inferior | El Castellar | — |
| MV-4, Miravete de la Sierra | Barremiense inferior | El Castellar | — |
| MV-5, Miravete de la Sierra | Barremiense inferior | El Castellar | — |
| MV-6, Miravete de la Sierra | Barremiense inferior | El Castellar | — |
| MV-7, Miravete de la Sierra | Barremiense inferior | El Castellar | — |
| MV-8, Miravete de la Sierra | Barremiense inferior | El Castellar | — |
| MV-9, Miravete de la Sierra | Barremiense inferior | El Castellar | — |
| Móra d’Ebre-Camposines, Sant Jeroni (CERAM collection) | Longobardiense | Muschelkalk | — |
| Móra d’Ebre-Camposines, Sant Jeroni (IPS collection) | Longobardiense | Muschelkalk | — |
| Múnter | Bartoniense | Vic-Manlleu Marls | Cataluña |
| Múnter | Bartoniense | Vic-Manlleu Marls | — |