| Uharte-Elkarte, Ezkaba Sandstone | Bartoniense | Ezkaba Sandstone | Comunidad Foral de Navarra |
| Ulea | Tortoniense | — | Región de Murcia |
| Umbría del Sastre tracksite | Berriasiense | Huérteles | — |
| Unit B (Galdames) | Aptiense inferior | Ernaga | — |
| Unit C | Aptiense superior | Tellamendi | — |
| Unit E | Albiense inferior | Itxina | — |
| Unit I | Albiense medio | Balmaseda | — |
| Unnamed seam, Rosario mine | Namuriense | — | Castilla y León |
| Upper Carazo Formation type area | Lochkoviense | Carazo | Castilla y León |
| Upper Carboniferous fauna from Demues Spain, Demues Fm | Kasimoviense | Demues | Principado de Asturias |
| Upper Carboniferous fauna San Emiliano Fm at Villafeliz | Bashkiriense | San Emiliano | Castilla y León |
| Upper Carboniferous fauna, Vergano Fm at Vergano | Moscoviense | Vergano | Castilla y León |
| Upper Dobrotivian diamictite beds, Aragoncillo | Dobrotiviense | Villar del Salz | Castilla-La Mancha |
| Upper Dobrotivian find sandstones, Aragoncillo | Dobrotiviense | San Marcos | Castilla-La Mancha |
| Upper Dobrotivian nodular shale beds, Aragoncillo | Dobrotiviense | San Marcos | Castilla-La Mancha |
| Upper Dobrotivian nodular shales, Sierra Menera | Dobrotiviense | San Marcos | Castilla-La Mancha |
| Upper Emsian assem from basal upper member of Moniello Fm, Asturias, NW Spain | Emsiense superior | Moniello | Principado de Asturias |
| Upper Emsian assem from basal upper member of Moniello Fm, East Pravia, NW Spain | Emsiense superior | Moniello | Principado de Asturias |
| Upper Emsian assem from the La Vid-Raneces Group Asturias, NW Spain | Emsiense superior | upper part | Principado de Asturias |
| Upper Emsian assem from the La Vid-Raneces Group Somiedo, Asturias, NW Spain | Emsiense superior | upper part | Principado de Asturias |
| Upper Emsian assem from the Raneces Group Capas de Aguion mem Asturias, NW Spain | Emsiense superior | Capas de Aguion | Principado de Asturias |
| Upper Emsian assem from the Raneces Grp Capas de Aguion mem Fenolleda, NW Spain | Emsiense superior | Capas de Aguion | Principado de Asturias |
| Upper Emsian assem from the Raneces Grp Capas de Aguion mem Ferrones, NW Spain | Emsiense superior | Capas de Aguion | Principado de Asturias |
| Upper Emsian assem from the upper La Vid-Raneces Group Asturias, NW Spain | Emsiense superior | upper part | Principado de Asturias |
| Upper Emsian assem from the upper Moniello Fm, Asturias, NW Spain | Emsiense superior | Moniello | Principado de Asturias |
| Upper Emsian assem from the upper Raneces Group, Asturias, NW Spain | Emsiense superior | upper part | Principado de Asturias |
| Upper Emsian assemblage from the basal Moniello Fm, Asturias, NW Spain | Emsiense superior | Moniello | Principado de Asturias |
| Upper Emsian assemblage from the basal Moniello Fm, Aviles, NW Spain | Emsiense superior | Moniello | Principado de Asturias |
| Upper Emsian assemblage from the upper La Vid Group, Leon, NW Spain | Emsiense superior | upper part | Castilla y León |
| Upper Emsian assemblage from the upper Moniello Fm, West Salinas, NW Spain | Emsiense superior | Moniello | Principado de Asturias |
| Upper Emsian assemblage from the upper Raneces Group, East La Plaza, NW Spain | Emsiense superior | upper part | Principado de Asturias |
| Upper Emsian athyrid from base of Moniello Fm, S. Cornellana, NW Spain | Emsiense superior | Moniello | Principado de Asturias |
| Upper Emsian athyrid from the Raneces Group, La Riera, NW Spain | Emsiense superior | Capas de Aguion | Principado de Asturias |
| Upper Emsian athyrid from the Raneces Group, South Belmonte de Miranda, NW Spain | Emsiense superior | Capas de Aguion | Principado de Asturias |
| Upper Givetian-Frasnian athyrid from the Canadas fm., NW Spain | Givetiense superior | Candas | Principado de Asturias |
| Upper horizon, Santed Fm., Celtiberia, Zaragoza, Spain | Arenig | Santed | Aragón |
| Upper La Vid Shale Locality Des-2 | Emsiense | — | Castilla y León |
| Upper Mbr, Armorican Quartzite Fm., Celtiberia, Zaragoza, Spain | Arenig | Armorican Quartzite | Aragón |
| Upper Muschelkalk, Henarejos, Cuenca Province | Ladiniense | Dolomite | Castilla-La Mancha |
| Upper Muschelkalk, Jalance | Ladiniense | Dolomite | Comunitat Valenciana |
| Upper Oretanian shale & siltstone beds, Aragoncillo | Oretaniense | Villar del Salz | Castilla-La Mancha |
| Upper Reef, Cati, Maestrazgo | Hauteriviense | Llacova | — |
| Urbasa Plateau | Luteciense | Urbasa-Andia | — |
| Utrillas | Albiense | Escucha | Aragón |
| Utrillas (Coquand collection) | Aptiense | Urgoniana | — |
| Utrillas (Verneuil collection) | Aptiense | Urgoniana | — |
| Utrillas-Eschucha | Albiense medio | Escucha | Aragón |
| Uztarrotz | Bartoniense | Margas de Pamplona | Comunidad Foral de Navarra |
| Uña | Barremiense superior | La Huérguina | Castilla-La Mancha |