Geology

Symbol	Name	Age	Description
QTs	Blanket Sand Deposits	Quaternary ? late Tertiary ?
QTs	Blanket Sand Deposits	Quaternary ? late Tertiary ?
Qb	Beach Deposits	Quaternary
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
Tcm	Camuy Formation	lower Pliocene-upper Miocene	Foraminiferal biomicrite with clay lenses, ferruginous calcarenite interbedded with chalky breccia, and upper chalky sandstone, sandstone, sandy limestone, and limestone. Estimated maximum thickness, l70 m. Exposed in the Manati, Barceloneta, Arecibo, C
Tv			Tertiary volcanic rocks
Kr	Robles Formation	Cenomanian-lower Albian	Chiefly volcaniclastic sandstone and siltstone, subordinate lava and minor limestone, conglomerate and breccia; includes at the base, in the Cayey quadrangle, a calcarenite. Two pillowed basaltic andesite flows are enclosed in sandstone-siltstone sequence
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
Tcb	Cibao Formation	lower Miocene-upper Oligocene	Calcareous clay, marl, and chalky limestone.
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
Kcoa	Coamo Formation	lower Maestrichtian-upper Santonian	Tuff, and volcanic breccia. Locally includes andesitic lava flows, and lenses of calcarenite. Maximum estimated thickness, 300 m. Exposed in the Coamo, Rio Descalabrado, Orocovis, Ponce, and Jayuya quadrangles
KJs	Serpentinite	Cretaceous ?-pre-Cretaceous ?	Sheared light- to dark-green, serpentinite; chiefly altered harzburgite. Epiclastic serpentinite is poorly sorted, unsheared, and retains a characteristic epiclastic appearance in both clasts and matrix. Exposed in the Mayaguez, Rosario, Maricao, Sabana
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
Trp	R??o Piedras Siltstone	upper Paleocene	Volcanic sandstone, siltstone, and basal conglomerate. Maximum thickness, l,400 m. Exposed in the Aguas Buenas, Naranjito and San Juan quadrangles
af	Artificial fill	Holocene
Kabcj	Formations A, B, C, and J	lower ?-upper ? Cretaceous	Non-pillowed lava flows, volcanic breccia, sandstone, conglomerate, and minor limestone, siltstone, and tuff. Estimated thickness exceeds 5,000 m. Exposed in the Cayey, Patillas, Caguas, Comerio, and Yabucoa quadrangles
Kr	Robles Formation	Cenomanian-lower Albian	Chiefly volcaniclastic sandstone and siltstone, subordinate lava and minor limestone, conglomerate and breccia; includes at the base, in the Cayey quadrangle, a calcarenite. Two pillowed basaltic andesite flows are enclosed in sandstone-siltstone sequence
Kta	Tabonuco Formation	middle or lower Cenomanian-Albian and ? Aptian	Volcaniclastic sandstone, mudstone, minor volcanic breccia, and conglomerate. Approximate thickness, 1,000 m. Exposed in the El Yunque, Fajardo, and Cayo Icacos quadrangles
Qa	Alluvium	Quaternary
Tjd	Juana Diaz Formation	middle Miocene-lower Oligocene	Basal gravel to conglomerate overlain by limestone. Maximum estimated thickness is 850 m. Exposed in the Ponce, Rio Descalabrado, Penuelas, Punta Cuchara, Yauco, Punta Verraco, Guanica, and Sabana Grande quadrangles
Kmo	Monacillo Formation	upper Cretaceous	Conglomerate and mudstone interbedded with siltstone and sandstone, locally a limestone. Maximum thickness estimated as less than 400 m. Exposed in the Aguas Buenas, Gurabo, San Juan, and Carolina quadrangles
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
Ks	Sabana Grande Formation	lower Maestrichtian-Turonian	Volcanic breccia, conglomerate, sandstone and siltstone, and minor basalt flows and limestone lenses. Minimum estimated thickness I,000 m. Exposed in the Sabana Grande, San German, Puerto Real, Mayaguez, and Rosario quadrangles
QTs	Blanket Sand Deposits	Quaternary ? late Tertiary ?
QTs	Blanket Sand Deposits	Quaternary ? late Tertiary ?
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
lTv			Eocene and Paleocene volcanic flows and associated pyroclastic and volcanoge
Qs	Swamp Deposits	Holocene-Pleistocene ?
Qa	Alluvium	Quaternary
TKmv	Metavolcanic Rocks	upper Cretaceous ?-Paleogene ?
TKy	Yauco Formation	Tertiary ?-middle ?-lower ? Maestrichtian-Cenomanian	Siltstone, claystone; sandstone, limestone, and conglomerate. Interbedding of the Yauco with the Maricao, Anon, and Lago Garzas, which have fossils of Tertiary age, may indicate an age spread from Tertiary to Upper Cretaceous, for the Yauco, but fossils
Qa	Alluvium	Quaternary
Ks	Sabana Grande Formation	lower Maestrichtian-Turonian	Volcanic breccia, conglomerate, sandstone and siltstone, and minor basalt flows and limestone lenses. Minimum estimated thickness I,000 m. Exposed in the Sabana Grande, San German, Puerto Real, Mayaguez, and Rosario quadrangles
Qb	Beach Deposits	Quaternary
Qa	Alluvium	Quaternary
TKm	Maricao Formation	Tertiary ? -Maestrichtian-Campanian	Volcanic trachybasalt breccia, tuffaceous sandstone and mudstone, tuff, and subordinate lava and limestone; characteristically contains large (l-3 cm long) augite phenocrysts. Estimated minimum thickness, 2,000 m. Exposed in the Maricao, Rosario, Centra
Kpob	Two pyroxene olivine basalt	lower ? Maestrichtian-Campanian	Porphyritic augite hypersthene-olivine basalt. Exposed in the Yauco, Sabana Grande, Guanica, Parguera, San German, Cabo Rojo, Mayaguez, Rosario, and Maricao quadrangles
TKm	Maricao Formation	Tertiary ? -Maestrichtian-Campanian	Volcanic trachybasalt breccia, tuffaceous sandstone and mudstone, tuff, and subordinate lava and limestone; characteristically contains large (l-3 cm long) augite phenocrysts. Estimated minimum thickness, 2,000 m. Exposed in the Maricao, Rosario, Centra
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
TKy	Yauco Formation	Tertiary ?-middle ?-lower ? Maestrichtian-Cenomanian	Siltstone, claystone; sandstone, limestone, and conglomerate. Interbedding of the Yauco with the Maricao, Anon, and Lago Garzas, which have fossils of Tertiary age, may indicate an age spread from Tertiary to Upper Cretaceous, for the Yauco, but fossils
TKy	Yauco Formation	Tertiary ?-middle ?-lower ? Maestrichtian-Cenomanian	Siltstone, claystone; sandstone, limestone, and conglomerate. Interbedding of the Yauco with the Maricao, Anon, and Lago Garzas, which have fossils of Tertiary age, may indicate an age spread from Tertiary to Upper Cretaceous, for the Yauco, but fossils
TKy	Yauco Formation	Tertiary ?-middle ?-lower ? Maestrichtian-Cenomanian	Siltstone, claystone; sandstone, limestone, and conglomerate. Interbedding of the Yauco with the Maricao, Anon, and Lago Garzas, which have fossils of Tertiary age, may indicate an age spread from Tertiary to Upper Cretaceous, for the Yauco, but fossils
Kd	Daguao Formation	lower Cretaceous ?	Massive andesitic interbedded volcaniclastic breccia, lava, and subordinate sandstone and crystal tuff. Maximum estimated thickness, l,000 m. Exposed in the Humacao, Naguabo, and Punta Puerca quadrangles
Qa	Alluvium	Quaternary
Qs	Swamp Deposits	Holocene-Pleistocene ?
TKy	Yauco Formation	Tertiary ?-middle ?-lower ? Maestrichtian-Cenomanian	Siltstone, claystone; sandstone, limestone, and conglomerate. Interbedding of the Yauco with the Maricao, Anon, and Lago Garzas, which have fossils of Tertiary age, may indicate an age spread from Tertiary to Upper Cretaceous, for the Yauco, but fossils
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
N/A			Not Availible
Qa	Alluvium	Quaternary
Qa	Alluvium	Quaternary
Tpo	Ponce Limestone	upper Miocene-Pliocene	Limestone with locally includes beds of brown clay. Maximum estimated thickness, 850 m. Exposed in the Ponce, R??o Descalabrado, Punta Cuchara, Yauco, Punta Verraco, Guanica, Parguera, San German, and Cabo Rojo quadrangles
Qa	Alluvium	Quaternary
Tr	R??o Culebrinas Formation	middle Eocene	Basal mudstone and limestone, breccia, tuff, and volcanic sandstone and mudstone. Maximum estimated thickness, 3,000 m. Exposed in the Central La Plata, Rincon, Aguadilla, San Sebastian, and Maricao quadrangles
Qb	Beach Deposits	Quaternary
QTs	Blanket Sand Deposits	Quaternary ? late Tertiary ?
Qa	Alluvium	Quaternary
Kg	Guynabo Formation	lower Santonian-upper Cenomanian	Interbedded volcanic sandstone and tuffaceous siltstone and volcanic conglomerate, pillowed andesitic lava flows at the base and middle of formation. Maximum thickness 1,600 m. Exposed in the Aguas Buenas quadrangle.
QTs	Blanket Sand Deposits	Quaternary ? late Tertiary ?
af	Artificial fill	Holocene
Q			Quaternary alluvium
Ks	Sabana Grande Formation	lower Maestrichtian-Turonian	Volcanic breccia, conglomerate, sandstone and siltstone, and minor basalt flows and limestone lenses. Minimum estimated thickness I,000 m. Exposed in the Sabana Grande, San German, Puerto Real, Mayaguez, and Rosario quadrangles
Ks	Sabana Grande Formation	lower Maestrichtian-Turonian	Volcanic breccia, conglomerate, sandstone and siltstone, and minor basalt flows and limestone lenses. Minimum estimated thickness I,000 m. Exposed in the Sabana Grande, San German, Puerto Real, Mayaguez, and Rosario quadrangles
Qa	Alluvium	Quaternary
Ts	San Sebastian Formation	middle ?-upper Oligocene	Shaley clay, sandstone, and conglomerate. Estimated maximum thickness, l00 m. in outcrop, about 328 m. in the subsurface. Exposed in the San Sebastian, Moca, Central La Plata, Bayaney, Utuado, Florida, Ciales, Corozal, Naranjito, Bayamon, and San Juan q
Kmo	Monacillo Formation	upper Cretaceous	Conglomerate and mudstone interbedded with siltstone and sandstone, locally a limestone. Maximum thickness estimated as less than 400 m. Exposed in the Aguas Buenas, Gurabo, San Juan, and Carolina quadrangles
TKdi	Diorite	Tertiary ?-upper Cretaceous ?	Porphyritic diorite. Exposed in the Fajardo, Naguabo, Corozal, Coamo, Rio Descalabrado, Rosario, Comerio, Aquas Buenas, Ciales, Central La Plata, Orocovis, Mayaguez, and Puerto Real quadrangles
Tcbr	R??o Indio Limestone Member	Tertiary	Limestone lenses of marly clay or beds of chalky limestone, grades into Mucarbones Sand laterally
Kcan	Cancel Breccia	upper ? Cretaceous	Andesitic tuff breccia, volcanic breccia, and lava. Maximum exposed thickness 2,000 m. Exposed in the Naranjito and Corozal quadrangles
lTv			Eocene and Paleocene volcanic flows and associated pyroclastic and volcanoge
lTv			Eocene and Paleocene volcanic flows and associated pyroclastic and volcanoge
Ts	San Sebastian Formation	middle ?-upper Oligocene	Shaley clay, sandstone, and conglomerate. Estimated maximum thickness, l00 m. in outcrop, about 328 m. in the subsurface. Exposed in the San Sebastian, Moca, Central La Plata, Bayaney, Utuado, Florida, Ciales, Corozal, Naranjito, Bayamon, and San Juan q
Kta	Tabonuco Formation	middle or lower Cenomanian-Albian and ? Aptian	Volcaniclastic sandstone, mudstone, minor volcanic breccia, and conglomerate. Approximate thickness, 1,000 m. Exposed in the El Yunque, Fajardo, and Cayo Icacos quadrangles
Qa	Alluvium	Quaternary
Ku	Granodiorite-quartz diorite of the Utuado batholith	post upper Paleocene- Santonian ?	Granodiorite, locally porphyritic, and subordinate quartz diorite, quartz monazite, and diorite. Exposed in the Jayuya, Bayaney, Utuado, and Adjuntas quadrangles
Tjo	Jobos Formation	Oligocene ?-pre-Oligocene?	Volcanic breccia, includes some volcanic conglomerate, sandstone, and andesitic lava flows. Estimated thickness, l,700 m. Exposed in the Utuado quadrangle
Qa	Alluvium	Quaternary
Q			Quaternary alluvium
Tv			Tertiary volcanic rocks
TKm	Maricao Formation	Tertiary ? -Maestrichtian-Campanian	Volcanic trachybasalt breccia, tuffaceous sandstone and mudstone, tuff, and subordinate lava and limestone; characteristically contains large (l-3 cm long) augite phenocrysts. Estimated minimum thickness, 2,000 m. Exposed in the Maricao, Rosario, Centra
Tjd	Juana Diaz Formation	middle Miocene-lower Oligocene	Basal gravel to conglomerate overlain by limestone. Maximum estimated thickness is 850 m. Exposed in the Ponce, Rio Descalabrado, Penuelas, Punta Cuchara, Yauco, Punta Verraco, Guanica, and Sabana Grande quadrangles
u			Ultramafic rocks
Q			Quaternary alluvium
Q			Quaternary alluvium
N/A			Not Availible
Q			Quaternary alluvium
Q			Quaternary alluvium
Q			Quaternary alluvium
uT			Post-Eocene marine strata
Q			Quaternary alluvium
Q			Quaternary alluvium
Q			Quaternary alluvium
Q			Quaternary alluvium
Q			Quaternary alluvium

107 Registers found