Geologic units in Somerset county, Maine

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

Devonian Seboomook Formation

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

Silurian - Ordovician Frontenac Formation

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

Silurian Sangerville Formation

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

Devonian - Silurian Madrid Formation

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

Ordovician quartz monzonite (hornblende accessory mineral)

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

Devonian Ironbound Mountain Formation

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

Devonian Carrabassett Formation massive pelite member

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

Devonian Tarratine Formation

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

Devonian granite

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

Precambrian gneisses of the Chain Lakes Massif

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

Cambrian Hurricane Mountain Formation

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

Silurian Waterville Formation

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

Ordovician - Cambrian Dead River formation lower member

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

Devonian granite-granodiorite (hornblende accessory mineral)

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

Devonian Tomhegan Formation

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

Devonian gabbro

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

Silurian Sangerville Formation Patch Mountain member

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

Silurian Smalls Falls Formation

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

Biotite granite undivided

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

Devonian Carrabassett Formation

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

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

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

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

Muscovite-biotite granite undivided

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

Silurian Perry Mountain formation

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

Silurian The Forks Formation

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

Muscovite-biotite granodiorite

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

Devonian - Ordovician unnamed pelite

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

Cambrian Jim Pond Formation

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

Silurian - Ordovician Vassalboro formation

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

Devonian Tarratine Formation Misery Quartzite

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

Silurian Sangerville Formation limestone member

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

Cambrian Jim Pond Formation, quartzwacke and pelite

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

Devonian gabbro - ultramafic rocks

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

Devonian Hildreths Formation

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

Devonian gabbro/diorite/ultramafic rocks

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

Silurian unnamed limestone

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

Ordovician - Cambrian Dead River formation upper member

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

Silurian Hardwood Mountain Formation

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

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

Devonian Carrabassett Formation thinly layered member

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

Devonian Seboomook Formation Day Mountain member

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

Devonian Seboomook Formation Temple Stream member

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

Ordovician Lobster Mountain volcanic complex

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

Cambrian gabbro/diorite/ultramafic rocks

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

Silurian Waterville Formation limestone member

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

Tomhegan Formation, Kineo Rhyolite Member, Massive Felsite

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

Silurian Unnamed sulfidic pelite

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

Silurian unnamed conglomerate

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

Devonian Hobbstown Formation

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

Silurian Sangerville Formation Anasagunticook member

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

Devonian unnamed garnet rhyolite

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

Cambrian Jim Pond Formation mafic volcanic rocks

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

Ordovician Kennebec Formation

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

Biotite granodiorite

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

Devonian Seboomook Formation Mount Blue member

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

Devonian Carrabassett Formation quartzite member

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

Devonian - Silurian unnamed conglomeratic sandstone

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

Devonian Seboomook Formation Camera Hill Greenstone

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

Devonian Heald Mountain Rhyolite

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

Silurian gabbro/diorite/ultramafic rocks

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

Ordovician Quimby formation graywacke member

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

Silurian Capens Formation

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

Devonian Parker Bog Formation

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

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

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).

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

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

Cambrian ultramafic rocks

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

Silurian unnamed mafic volcanic rocks

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

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

Biotite granite, biotite granodiorite, biotite tonalite, biotite quartz syenite, biotite quartz monzodiorite, and biotite quartz diorite.

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

Cambrian Hurricane Mountain Formation, metaquartzwacke

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

Cambrian Hurricane Mountain Formation, metagabbro

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

Ordovician biotite granodiorite

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

Devonian Heald Mountain Rhyolite dark tuff member

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

Ordovician biotite granite

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

Devonian Tarratine Formation McKenny Pond Limestone

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

Cambrian Hurricane Mountain Formation, amphibolite and greenschist

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

Cambrian Hurricane Mountain Formation, metapyroxenite

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

Ordovician biotite granite undivided

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

Devonian Beck Pond Limestone

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

Cambrian Hurricane Mountain Formation, metafelsite

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

Devonian unnamed mafic volcanic rocks

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

Unnamed volcanic rocks

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

Silurian Sangerville Formation conglomerate member