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Mineral Resources > Online Spatial Data > Geology > by state > Maine Geology

Geologic units in Somerset county, Maine

[Additional scientific data in this geographic area]

Devonian Tomhegan Formation Kineo Rhyolite member tuffs and volcaniclastic rocks (Devonian) at surface, covers 0.2 % of this area

Devonian Tomhegan Formation Kineo Rhyolite member tuffs and volcaniclastic rocks

Lithology: rhyolite

Silurian Waterville Formation limestone member (Silurian) at surface, covers 0.1 % of this area

Silurian Waterville Formation limestone member

Lithology: calc-silicate rock; metasedimentary rock; marble; slate; schist; black shale

Silurian Capens Formation (Silurian) at surface, covers < 0.1 % of this area

Silurian Capens Formation

Lithology: slate; conglomerate

Devonian granite-granodiorite (hornblende accessory mineral) (Devonian) at surface, covers 2 % of this area

Devonian granite-granodiorite (hornblende accessory mineral)

Lithology: granite; granodiorite

Silurian The Forks Formation (Silurian) at surface, covers 0.7 % of this area

Silurian The Forks Formation

Lithology: metasedimentary rock; marble

Silurian Sangerville Formation conglomerate member (Silurian) at surface, covers < 0.1 % of this area

Silurian Sangerville Formation conglomerate member

Lithology: conglomerate

Devonian Tarratine Formation McKenny Pond Limestone (Devonian) at surface, covers < 0.1 % of this area

Devonian Tarratine Formation McKenny Pond Limestone

Lithology: limestone; slate; sandstone

Silurian Unnamed sulfidic pelite (Silurian) at surface, covers < 0.1 % of this area

Silurian Unnamed sulfidic pelite

Lithology: mudstone

Devonian Beck Pond Limestone (Devonian) at surface, covers < 0.1 % of this area

Devonian Beck Pond Limestone

Lithology: limestone; dolostone (dolomite); sandstone; mudstone

Cambrian Jim Pond Formation, quartzwacke and pelite (Cambrian) at surface, covers 0.4 % of this area

Cambrian Jim Pond Formation, quartzwacke and pelite

Lithology: sandstone; mudstone

Devonian Heald Mountain Rhyolite dark tuff member (Devonian) at surface, covers < 0.1 % of this area

Devonian Heald Mountain Rhyolite dark tuff member

Lithology: rhyolite

Devonian granodiorite (Devonian) at surface, covers < 0.1 % of this area

Devonian granodiorite - biotite granodiorite

Lithology: granodiorite

Cambrian Hurricane Mountain Formation, metagabbro (Cambrian) at surface, covers < 0.1 % of this area

Cambrian Hurricane Mountain Formation, metagabbro

Lithology: gabbro

Devonian Tomhegan Formation Kineo Rhyolite member garnet rhyolite (Devonian) at surface, covers < 0.1 % of this area

Devonian Tomhegan Formation Kineo Rhyolite member garnet rhyolite

Lithology: rhyolite

Silurian Sangerville Formation limestone member (Silurian) at surface, covers 0.4 % of this area

Silurian Sangerville Formation limestone member

Lithology: marble; calc-silicate rock; granofels; schist

Silurian - Ordovician Vassalboro formation (Silurian - Ordovician) at surface, covers 0.4 % of this area

Silurian - Ordovician Vassalboro formation

Lithology: sandstone; quartzite; schist; limestone

Cambrian gabbro/diorite/ultramafic rocks (Cambrian) at surface, covers 0.1 % of this area

Cambrian gabbro/diorite/ultramafic rocks

Lithology: gabbro; diorite; ultramafic intrusive rock

Silurian Smalls Falls Formation (Silurian) at surface, covers 1 % of this area

Silurian Smalls Falls Formation

Lithology: shale; sandstone; calc-silicate rock

Devonian Seboomook Formation Day Mountain member (Devonian) at surface, covers 0.2 % of this area

Devonian Seboomook Formation Day Mountain member

Lithology: metasedimentary rock; schist

Silurian Hardwood Mountain Formation (Silurian) at surface, covers 0.2 % of this area

Silurian Hardwood Mountain Formation

Lithology: mudstone; siltstone; slate, conglomerate, limestone, sandstone

Silurian unnamed conglomerate (Silurian) at surface, covers < 0.1 % of this area

Silurian unnamed conglomerate

Lithology: conglomerate; quartz-feldspar schist

Cambrian ultramafic rocks (Cambrian) at surface, covers < 0.1 % of this area

Cambrian ultramafic rocks

Lithology: ultramafic intrusive rock

Devonian granite (Devonian) at surface, covers 3 % of this area

Devonian granite

Lithology: granite

Silurian Sangerville Formation Anasagunticook member (Silurian) at surface, covers < 0.1 % of this area

Silurian Sangerville Formation Anasagunticook member

Lithology: metasedimentary rock; marble

Silurian Sangerville Formation (Silurian) at surface, covers 7 % of this area

Silurian Sangerville Formation

Lithology: sandstone; shale; limestone; calc-silicate rock; granofels; schist; metasedimentary rock; conglomerate

Devonian - Ordovician unnamed pelite (Devonian - Ordovician) at surface, covers 0.4 % of this area

Devonian - Ordovician unnamed pelite

Lithology: mudstone

Devonian gabbro/diorite/ultramafic rocks (Devonian) at surface, covers 0.4 % of this area

Devonian gabbro/diorite/ultramafic rocks

Lithology: gabbro; diorite; ultramafic intrusive rock

Silurian - Ordovician Frontenac Formation (Silurian - Ordovician) at surface, covers 9 % of this area

Silurian - Ordovician Frontenac Formation

Lithology: graywacke; slate

Unnamed volcanic rocks (Devonian - Silurian) at surface, covers < 0.1 % of this area

Unnamed volcanic rocks

Lithology: felsic volcanic rock; mafic volcanic rock

Silurian Perry Mountain formation (Silurian) at surface, covers 0.7 % of this area

Silurian Perry Mountain formation

Lithology: sandstone; shale; quartzite

Cambrian Hurricane Mountain Formation, black and gray metaquartzite (Cambrian) at surface, covers < 0.1 % of this area

Cambrian Hurricane Mountain Formation, black and gray metaquartzite

Lithology: quartzite

Devonian unnamed garnet rhyolite (Devonian) at surface, covers < 0.1 % of this area

Devonian unnamed garnet rhyolite

Lithology: rhyolite

Devonian gabbro (Devonian) at surface, covers 1 % of this area

Devonian gabbro

Lithology: gabbro

Devonian Hobbstown Formation (Devonian) at surface, covers < 0.1 % of this area

Devonian Hobbstown Formation

Lithology: arkose; conglomerate

Cambrian Hurricane Mountain Formation (Cambrian) at surface, covers 3 % of this area

Cambrian Hurricane Mountain Formation

Lithology: melange

Devonian Carrabassett Formation (Devonian) at surface, covers 1 % of this area

Devonian Carrabassett Formation

Lithology: schist; metasedimentary rock; gneiss

Silurian unnamed mafic volcanic rocks (Silurian) at surface, covers < 0.1 % of this area

Silurian unnamed mafic volcanic rocks

Lithology: mafic volcanic rocks

Ordovician - Cambrian Dead River formation lower member (Ordovician - Cambrian) at surface, covers 2 % of this area

Ordovician - Cambrian Dead River formation lower member

Lithology: quartzite; phyllite

Devonian Hildreths Formation (Devonian) at surface, covers 0.4 % of this area

Devonian Hildreths Formation

Lithology: calc-silicate rock; marble; graywacke; schist

Devonian Tarratine Formation (Devonian) at surface, covers 4 % of this area

Devonian Tarratine Formation

Lithology: sandstone; slate; siltstone; limestone; quartzite

Devonian Tarratine Formation Misery Quartzite (Devonian) at surface, covers 0.4 % of this area

Devonian Tarratine Formation Misery Quartzite

Lithology: quartzite

Devonian Seboomook Formation Temple Stream member (Silurian-Devonian) at surface, covers 0.1 % of this area

Devonian Seboomook Formation Temple Stream member

Lithology: schist; metasedimentary rock; conglomerate

Tomhegan Formation, Kineo Rhyolite Member, Massive Felsite (Devonian) at surface, covers < 0.1 % of this area

Tomhegan Formation, Kineo Rhyolite Member, Massive Felsite

Lithology: rhyolite

Ordovician granite (Ordovician) at surface, covers < 0.1 % of this area

Ordovician granite - Ordovician biotite granite undivided

Lithology: granite

Devonian Seboomook Formation Camera Hill Greenstone (Devonian) at surface, covers < 0.1 % of this area

Devonian Seboomook Formation Camera Hill Greenstone

Lithology: greenstone

Silurian - Ordovician Frontenac Formation Canada Falls volcanic member (Silurian - Ordovician) at surface, covers 0.9 % of this area

Silurian - Ordovician Frontenac Formation Canada Falls volcanic member

Lithology: basalt

Devonian Carrabassett Formation thinly layered member (Devonian) at surface, covers 0.2 % of this area

Devonian Carrabassett Formation thinly layered member

Lithology: mudstone; sandstone

Devonian Seboomook Formation Mount Blue member (Devonian) at surface, covers < 0.1 % of this area

Devonian Seboomook Formation Mount Blue member

Lithology: schist; metasedimentary rock

Devonian Ironbound Mountain Formation (Devonian) at surface, covers 4 % of this area

Devonian Ironbound Mountain Formation

Lithology: slate

Devonian Carrabassett Formation massive pelite member (Devonian) at surface, covers 4 % of this area

Devonian Carrabassett Formation massive pelite member

Lithology: mudstone

Devonian - Silurian Madrid Formation (Devonian - Silurian) at surface, covers 7 % of this area

Devonian - Silurian Madrid Formation

Lithology: quartzite; calc-silicate rock

Devonian granite-quartz diorite (Devonian) at surface, covers < 0.1 % of this area

Devonian granite-quartz diorite: biotite granite, biotite granodiorite, biotite tonalite, biotite quartz syenite, biotite quartz monzodiorite, and biotite quartz diorite.

Lithology: granite; granodiorite; tonalite; quartz syenite; quartz monzodiorite; quartz diorite

Devonian - Silurian unnamed conglomeratic sandstone (Devonian - Silurian) at surface, covers < 0.1 % of this area

Devonian - Silurian unnamed conglomeratic sandstone

Lithology: sandstone

Devonian unnamed mafic volcanic rocks (Devonian) at surface, covers < 0.1 % of this area

Devonian unnamed mafic volcanic rocks

Lithology: mafic volcanic rock

Cambrian Jim Pond Formation (Cambrian) at surface, covers 0.4 % of this area

Cambrian Jim Pond Formation

Lithology: greenstone; felsic metavolcanic rock; metasedimentary rock, amphibolite, iron formation

Precambrian gneisses of the Chain Lakes Massif (Precambrian) at surface, covers 3 % of this area

Precambrian gneisses of the Chain Lakes Massif

Lithology: felsic gneiss

Ordovician Lobster Mountain volcanic complex (Ordovician) at surface, covers 0.1 % of this area

Ordovician Lobster Mountain volcanic complex

Lithology: felsic volcanic rock; conglomerate

Cambrian Jim Pond Formation mafic volcanic rocks (Cambrian) at surface, covers < 0.1 % of this area

Cambrian Jim Pond Formation mafic volcanic rocks

Lithology: greenstone

Ordovician granodiorite (Ordovician) at surface, covers < 0.1 % of this area

Ordovician granodiorite - Ordovician biotite granodiorite

Lithology: granodiorite

Devonian granodiorite (muscovite accessory mineral) (Devonian) at surface, covers 0.5 % of this area

Devonian granodiorite (muscovite accessory mineral) - muscovite-biotite granodiorite

Lithology: granodiorite

Devonian Heald Mountain Rhyolite (Devonian) at surface, covers < 0.1 % of this area

Devonian Heald Mountain Rhyolite

Lithology: rhyolite

Cambrian Hurricane Mountain Formation, metapyroxenite (Cambrian) at surface, covers < 0.1 % of this area

Cambrian Hurricane Mountain Formation, metapyroxenite

Lithology: pyroxenite

Devonian Carrabassett Formation quartzite member (Devonian) at surface, covers < 0.1 % of this area

Devonian Carrabassett Formation quartzite member

Lithology: quartzite

Silurian Sangerville Formation Patch Mountain member (Silurian) at surface, covers 1 % of this area

Silurian Sangerville Formation Patch Mountain member

Lithology: marble; calc-silicate rock; granofels; schist

Devonian granodiorite - quartz syenite (porphyritic texture) (Devonian) at surface, covers 0.9 % of this area

Devonian granodiorite - quartz syenite (porphyritic texture) - Devonian porphyritic biotite granodiorite to quartz syenite - porphyritic biotite granodiorite, porphyritic biotite tonalite, porphyritic alkali feldspar-biotite quartz syenite, and porphyritic biotite quartz syenite.

Lithology: granodiorite; tonalite; quartz syenite

Cambrian Jim Pond Formation siltstone, mudstone, and pelite (Cambrian) at surface, covers < 0.1 % of this area

Cambrian Jim Pond Formation siltstone, mudstone, and pelite

Lithology: mudstone; siltstone

Cambrian Hurricane Mountain Formation, metaquartzwacke (Cambrian) at surface, covers < 0.1 % of this area

Cambrian Hurricane Mountain Formation, metaquartzwacke

Lithology: sandstone

Ordovician Kennebec Formation (Ordovician) at surface, covers < 0.1 % of this area

Ordovician Kennebec Formation

Lithology: rhyolite

Devonian Parker Bog Formation (Devonian) at surface, covers < 0.1 % of this area

Devonian Parker Bog Formation

Lithology: limestone; tuff

Cambrian Jim Pond Formation, felsic volcanic rocks (Cambrian) at surface, covers < 0.1 % of this area

Cambrian Jim Pond Formation, felsic volcanic rocks Volcanic and metasedimentary rocks of the ophiolite sequence in central-western Maine are here named the Jim Pond Formation. It consists of a basal chlorite-albite-epidote-actinolite greenstone member with minor metagraywacke, 150 to 500 m thick. Northwest of the Squirtgun fault it is divided into lower and upper units by a metadacite member in the east, 0 to >500 m thick, and a metagraywacke member in the west. The metadacite member is closely associated with hematitic chert iron-formation members. Greenstone is thickly layered with pillowed and massive flows. Patches of altered amphibolite are in contact with the southeastern belt of tonalite of the Boil Mountain Complex. (ME075) Unit description from USGS GEOLEX website (ME078).

Lithology: felsic volcanic rock

Devonian granite (porphyritic texture) (Devonian) at surface, covers 1 % of this area

Devonian granite (porphyritic texture) - biotite granite undivided

Lithology: granite

Silurian gabbro/diorite/ultramafic rocks (Silurian) at surface, covers < 0.1 % of this area

Silurian gabbro/diorite/ultramafic rocks

Lithology: gabbro; diorite; ultramafic intrusive rock

Cambrian Hurricane Mountain Formation, Amphibolite and Greenschist (Cambrian) at surface, covers < 0.1 % of this area

Cambrian Hurricane Mountain Formation, amphibolite and greenschist

Lithology: basalt

Ordovician quartz monzonite (hornblende accessory mineral) (Ordovician) at surface, covers 4 % of this area

Ordovician quartz monzonite (hornblende accessory mineral)

Lithology: quartz monzonite

Devonian gabbro - ultramafic rocks (Devonian) at surface, covers 0.4 % of this area

Devonian gabbro - ultramafic rocks

Lithology: gabbro; ultramafic intrusive rock

Ordovician granite (Ordovician) at surface, covers < 0.1 % of this area

Ordovician granite - Ordovician biotite granite

Lithology: granite

Ordovician - Cambrian Dead River formation upper member (Ordovician - Cambrian) at surface, covers 0.2 % of this area

Ordovician - Cambrian Dead River formation upper member

Lithology: phyllite; quartzite

Ordovician Quimby formation graywacke member (Ordovician) at surface, covers < 0.1 % of this area

Ordovician Quimby formation graywacke member

Lithology: graywacke

Devonian granite (muscovite accessory mineral) (Devonian) at surface, covers 0.8 % of this area

Devonian granite (muscovite accessory mineral) - muscovite-biotite granite undivided

Lithology: granite

Devonian Seboomook Formation (Devonian) at surface, covers 26 % of this area

Devonian Seboomook Formation

Lithology: mudstone; sandstone

Silurian Waterville Formation (Silurian) at surface, covers 3 % of this area

Silurian Waterville Formation

Lithology: slate; schist; graywacke; calc-silicate rock; black shale

Silurian unnamed limestone (Silurian) at surface, covers 0.4 % of this area

Silurian unnamed limestone

Lithology: limestone; dolostone (dolomite)

Devonian Tomhegan Formation (Devonian) at surface, covers 2 % of this area

Devonian Tomhegan Formation

Lithology: sandstone; slate; quartzite

Cambrian Hurricane Mountain Formation, metafelsite (Cambrian) at surface, covers < 0.1 % of this area

Cambrian Hurricane Mountain Formation, metafelsite

Lithology: rhyolite