{"text_format":"dbase-jsonl-2026-09-30","columns":[{"name":"AGE","type":"character","width":36},{"name":"CLASS","type":"number","width":3,"decimals":0},{"name":"DESCRIPTIO","type":"character","width":254},{"name":"FOSSIL","type":"character","width":229},{"name":"MAP_UNIT","type":"character","width":5},{"name":"MOD_DATE","type":"date","width":8},{"name":"MOD_NOTES","type":"character","width":25},{"name":"NSACLASS","type":"number","width":5,"decimals":0},{"name":"NSAMOD","type":"character","width":3},{"name":"QCLASS","type":"number","width":4,"decimals":0},{"name":"QUADRANGLE","type":"character","width":14},{"name":"RADIOMETRI","type":"character","width":100},{"name":"ROCK_CLASS","type":"character","width":14},{"name":"SOURCE","type":"character","width":5},{"name":"UNIT_NAME","type":"character","width":52}],"n_rows":34,"rows_kept":34,"cut":false,"deleted_skipped":0,"read_ended":"whole","bounds":"16MiB/16384/4096/first_that_fit","version":"dbase_level_three","encoding_class":"enc_single_byte","reader":"statdb_count/9"}
["Quaternary",110,"Surficial deposits. Thin cover of beach, bar, and alluvial deposits, inculuding gravel, sand, silt, and peat",null,"Qs","2010-08-09",null,100,null,1000,"Saint Lawrence",null,"Unconsolidated","SL002","Surficial deposits"]
["Quaternary",111,"Glacial drift along north coast between Akeftapak Bay and Kangee Camp.  Till and outwash of Illinoian age",null,"Qsg","2010-04-08",null,190,null,1900,"Saint Lawrence",null,"Unconsolidated","SL002","Glacial drift"]
["Pleistocene",112,"Nearly flatlying basalt flows. Fresh medium- to dark-gray alkali olivine basalt in massive columnar jointed flows",null,"Qb","2010-04-08",null,330,null,3300,"Saint Lawrence","K/Ar age of 0.238 to 1.46 m.y.","Igneous","SL002","Basalt"]
["Oligocene",115,"Poorly sorted sandstone, grit, and conglomerate, carbonaceous mudstone, ashy tuff, volcanic breccia, and seams of lignitic coal","Plant fossils","Ts",null,null,640,null,null,"Saint Lawrence",null,"Sedimentary","SL002","Sandstone, coal, and tuff"]
["Oligocene",116,"Rhyolitic and dacitic tuffs. Chiefly pale-reddish-orange to gray welded tuff, ash-fall tuff, tuff breccia, and flows of felsic composition","Abundant plant fossils","Tr",null,null,1070,null,null,"Saint Lawrence","K/Ar age of 39.3 m.y.","Igneous","SL002","Rhyolitic and dacitic tuffs"]
["Paleocene",117,"Light-gray to drab unaltered soda rhyolite flows composed of large phenocrysts of twinned sanidine and reddish brown hornblende in a fine-grained trachytic groundmass. Fine-grained dark basalt",null,"Tsr",null,null,1145,null,null,"Saint Lawrence","K/Ar of 62.1 and 64.4 m.y. on hornblende and sanadine and 64.0 m.y. on whole-rock aample of trachyte","Igneous","SL002","Soda rhyolite and basalt"]
["Tertiary and (or) Cretaceous",118,"Scattered exposures of flows, tuffs, and hypabyssal intrusive rocks. Composition range of basaltic to rhyolitic",null,"TKv",null,null,1600,null,null,"Saint Lawrence",null,"Igneous","SL002","Undifferentiated volcanic rocks"]
["Cretaceous",120,"Chiefly quartz monzonite but includes granodiorite, monzonite, syenite, and alaskite",null,"Kq",null,null,2491,null,null,"Saint Lawrence","K/Ar age of 93.5 to 108 m.y.","Igneous","SL002","Quartz monzonite"]
["Cretaceous",121,"Nepheline Syenite. Light- to medium-gray medium- to coarse-grained granitic to seriate textured rock with k-spar phenocrysts",null,"Kn",null,null,2535,null,null,"Saint Lawrence",null,"Igneous","SL002","Nepheline Syenite"]
["Cretaceous",122,"Olivine-bearing syenodiorite. Medium to dark greenish gray, coarse to medium grained, and granitic textured.",null,"Ko",null,null,2491,null,null,"Saint Lawrence",null,"Igneous","SL002","Olivine-bearing syenodiorite"]
["Cretaceous",123,"Andesitic volcanic rocks. Flows, hypabyssal intrusive rocks, and volcaniclastic rocks. Cheifly andesitic and latitic in composition, but range from basaltic to rhyolitic. Locally altered to hornfels near plutons",null,"Kv",null,null,2330,null,null,"Saint Lawrence","K/Ar of 90.9 m.y. from crystal tuff","Igneous","SL002","Andesitic volcanic rocks"]
["Late and Middle Triassic",125,"Upper member: Black shale, dark thin-bedded limestone, and chert. Lower member: Thin-bedded chert and dark siltstone. Locally altered to hornfels near plutons","Daonella, Halobia and Monotis clams","Trs",null,null,4110,null,null,"Saint Lawrence",null,"Sedimentary","SL002","Shale, limestone, and chert"]
["Triassic and Permian",126,"Fine-grained to gritty dark carbonaceous graywacke and dark carbonaceous shale. Deformed and sheared. Locally altered to hornfels near plutons",null,"TrPs","2010-04-26","Assigned to Etivluk Group",5000,null,null,"Saint Lawrence",null,"Sedimentary","SL002","Graywacke, grit and shale"]
["Triassic and Permian",127,"Dark-greenish-gray rusty weathered altered gabbro and diabase",null,"TrPg",null,null,5140,null,null,"Saint Lawrence","K/Ar ages of 221 and 244 Ma","Igneous","SL002","Gabbro and diabase"]
["Late Mississippian",130,"Lower member: Dark-gray thin-bedded limestone with abundant dark chert nodules. Upper member: Light- to medium-gray medium to coarsely bioclastic limestone. Contact metamorphosed to marble near plutons","Coral, brachiopods, and foraminiferal fauna of Late Mississippian age including Gigantoproductus, Lithostrotionella, and endothyrids","Ml",null,null,6320,null,null,"Saint Lawrence",null,"Sedimentary","SL002","Limestone"]
["Late and Middle Devonian",135,"Medium-gray to brown laminated, locally brecciated dolomite and dolomitic limestone. Contact metamorphosed to marble near plutons","Stromatoporoid (Amphipora?), tabulate corals (Favosites and thamnoporoid forms), atrypids (Atrypa and Spinatrypa), spiriferoids (Koziowskiellisia? sp. and Mucrospirifera? sp.) and Coelocaulis-like gastropod","Dd",null,null,6982,null,null,"Saint Lawrence",null,"Sedimentary","SL002","Dolomite and dolomitic limestone"]
["Paleozoic or Precambrian",140,"Highly crenulated banded, thick layers of pale-gray, green, and lavender calc-silicate hornfels alternating with thin layers of dark argillaceous hornfels",null,"PzpCc",null,null,12950,"HFS",null,"Saint Lawrence",null,"Metamorphic","SL002","Calc-silicate hornfels"]
["Quaternary",300,"Unit composed of gravel and sand eroded from the underlying bedrock platform and silt and sand alluvium eroded from upland areas.  Location and physiographic expression-Unit includes active beach and bar deposits along the present shoreline and former be",null,"Qs","2010-11-16",null,100,null,1000,"Saint Lawrence",null,"Unconsolidated","SL003","Beach, bar, and alluvial deposits"]
["Quaternary",310,"Till and outwash gravel of probable late isotpe stage 5 or  isotope stage 4 (early Wisconsin) age deposited by an ice sheet that extended across the Bering Sea shelf from the Chukotsk Peninsula in northeastern Russia to Saint Lawrence Island (Hopkins and",null,"Qg","2010-06-01",null,190,null,1900,"Saint Lawrence",null,"Unconsolidated","SL003","Glacial drift"]
["early Tertiary",320,"Poorly consolidated sandstone, grit and conglomerate, carbonaceous mudstone, ashy tuff, volcanic breccia, and seams of lignitic coal as much as 60 cm thick.  Unit is poorly exposed and badly slumped.  Total thickness probably does not exceed 25 m.  Abund",null,"Ts",null,null,640,null,null,"Saint Lawrence",null,"Sedimentary","SL003","Sandstone, coal, and tuff"]
["Quaternary",330,"Flat lying to gently dipping lava flows and interlayered tuffs and breccias composed chiefly of alkali olivine basalt, olivine tholeiite, and minor amounts of basanite, hawaiite, and nephelinite (Moll-Stalcup, 1994). Numerous small cinder cones and flows",null,"Qb","2010-04-08",null,330,null,3300,"Saint Lawrence",null,"Igneous","SL003","Basalt"]
["early Tertiary",340,"Pale-reddish-orange to gray welded tuff, ash-fall tuff, tuff breccia, and flows of felsic composition (Patton and Csejtey, 1980).  On Fossil River unit contains a thin sequence of quartzose sandstone, quartz-chert conglomerate, volcanic conglomerate, and",null,"Tr",null,null,1070,null,null,"Saint Lawrence",null,"Igneous","SL003","Rhyolitic and dacitic tuffs"]
["early Tertiary and latest Cretaceous",350,"Soda rhyolite flows composed of large phenocrysts of twinned sanidine and reddish-brown hornblende in a fine-grained trachytic groundmass.  Unit locally includes basalt, trachyandesite, and andesite, lava flows and small hypabyssal bodies of rhyolite, an",null,"TKsr",null,null,1145,null,null,"Saint Lawrence",null,"Igneous","SL003","Soda rhyolite and basalt"]
["Tertiary and (or) Cretaceous",360,"Unit composed of flows, tuffs, and hypabyssal intrusive rocks that range in composition from basaltic to rhyolitic and are commonly altered.  Age is uncertain but probably no older than Cretaceous.  Location-Exposures of this unit occur at several widely",null,"TKv",null,null,1600,null,null,"Saint Lawrence",null,"Igneous","SL003","Volcanic rocks, undivided"]
["Late and Early Cretaceous",370,"Unit composed of granite and subordinate granodiorite, monzonite, syenite, and alaskite.  The rocks vary in texture from coarse to fine-grained and from granitic to porphyritic and seriate.  Three broad categories are recognizable: 1) granite, granodiori",null,"Kg","2010-11-15",null,2491,null,null,"Saint Lawrence",null,"Igneous","SL003","Granite and granodiorite"]
["Early Cretaceous",380,"Monzodiorite composed of a medium- to coarse-grained granitic textured rock composed chiefly of plagioclase, K-feldspar, augite, olivine, and biotite.  Accessory minerals include apatite, zircon, and magnetite.  A biotite sample from this unit yielded an",null,"Ko","2010-11-16",null,2491,null,null,"Saint Lawrence",null,"Igneous","SL003","Olivine-bearing monzodiorite"]
["Early Cretaceous",390,"A medium- to coarse-grained granitic textured rock with K-feldspar phenocrysts as much as 4 cm long.  Rock-forming minerals are K-feldspar, nepheline, biotite, and melanite garnet with subordinate amounts of sodic andesine and hornblende.  Accessory mine",null,"Kn",null,null,2535,null,null,"Saint Lawrence",null,"Igneous","SL003","Nepheline syenite"]
["Cretaceous",400,"Unit includes a wide variety of flows, hypabyssal intrusive rocks and volcaniclastic rocks composed chiefly of andesite and trachyandesite but range from basalt to rhyolite.  Volcaniclastic rocks vary from lithic and crystal tuffs and breccias to volcani",null,"Kv",null,null,2330,null,null,"Saint Lawrence",null,"Igneous","SL003","Andesitic volcanic rocks"]
["Triassic",410,"Unit consists of an upper member, 50m thick, composed of black shale, dark thin-bedded limestone, and chert; and a lower member, 70m thick, composed of thin-bedded chert and dark siltstone.  The upper member contains flat clams, Daonella, Halobia, and Mo","Daonella, Halobia and Monotis clams","Trs",null,null,4110,null,null,"Saint Lawrence",null,"Sedimentary","SL003","Shale, limestone, and chert, Ongoveyuk terrane"]
["Late Mississippian",420,"Unit composed of an upper and lower member. The upper member consists chiefly of light- to medium -gray coarsely bioclastic limestone that contains interbedded limey mudstone in the upper part.  The lower member is composed of dark-gray thin-bedded limes","Assigned a Late Mississippian age on the basis of an abundant coral, brachiopod, foraminifera, and conodont fauna (Patton and Dutro, 1969) (Lane and Ressmeyer, 1985) (Zhang and Blodgett 2007)","Ml",null,null,6320,null,null,"Saint Lawrence",null,"Sedimentary","SL003","Limestone, Ongoveyuk terrane"]
["Devonian",430,"Medium-gray to brown, laminated, locally brecciated dolomite and dolomitic limestone.  Grades into dark, fine-grained, thin-bedded dolomite in upper part.  Unit metamorphosed to a sugary-textured marble along contacts with granitic plutons.  The total th","Assigned a probable Late and Middle Devonian age on the basis of an abundant fauna that includes Amphipora (?), tabulate and thamnoporoid corals, and assorted brachiopod species (Patton and Dutro, 1969) (Zhang and Blodgett, 2007)","Dd","2010-11-16",null,6982,null,null,"Saint Lawrence",null,"Sedimentary","SL003","Dolostone and dolomitic limestone, Ongoveyuk terrane"]
["Triassic and Permian?",440,"Unit composed of dark fine-grained to gritty carbonaceous graywacke, dark carbonaceous shale, and subordinate bedded chert and siliceous mudstone. The graywacke clasts consist mainly of quartz but also include plagioclase, K-feldspar, shale, chert, grani",null,"TrPs","2010-04-26","Assigned to Etivluk Group",5000,null,null,"Saint Lawrence",null,"Sedimentary","SL003","Graywacke, grit, and shale, Tomnamie terrane"]
["Triassic and Permian",450,"Unit composed of rusty-weathering altered gabbro and diabase and subordinate amounts of siliceous mudstone, laminated tuff, basalt, fine-grained graywacke, and slate.  The gabbro and diabase consist mainly of clinopyroxene, plagioclase, hornblende, and o",null,"TrPg",null,null,5140,null,null,"Saint Lawrence",null,"Igneous","SL003","Gabbro and diabase, Tomnamie terrane"]
["Paleozoic?",460,"Unit composed of a highly crenulated banded rock consisting of 0.5- to 10-cm-thick layers of pale gray, green and lavender calc-silicate hornfels alternating with thinner layers of dark argillaceous hornfels.  The calc-silicate hornfels is composed chief",null,"Pzu",null,null,12950,"HFS",null,"Saint Lawrence",null,"Metamorphic","SL003","Calc-silicate hornfels"]