- Abstract
- Affiliation
- All
- Authors
- Book Series
- DOI
- EISBN
- EISSN
- Full Text
- GeoRef ID
- ISBN
- ISSN
- Issue
- Keyword (GeoRef Descriptor)
- Meeting Information
- Report #
- Title
- Volume
- Abstract
- Affiliation
- All
- Authors
- Book Series
- DOI
- EISBN
- EISSN
- Full Text
- GeoRef ID
- ISBN
- ISSN
- Issue
- Keyword (GeoRef Descriptor)
- Meeting Information
- Report #
- Title
- Volume
- Abstract
- Affiliation
- All
- Authors
- Book Series
- DOI
- EISBN
- EISSN
- Full Text
- GeoRef ID
- ISBN
- ISSN
- Issue
- Keyword (GeoRef Descriptor)
- Meeting Information
- Report #
- Title
- Volume
- Abstract
- Affiliation
- All
- Authors
- Book Series
- DOI
- EISBN
- EISSN
- Full Text
- GeoRef ID
- ISBN
- ISSN
- Issue
- Keyword (GeoRef Descriptor)
- Meeting Information
- Report #
- Title
- Volume
- Abstract
- Affiliation
- All
- Authors
- Book Series
- DOI
- EISBN
- EISSN
- Full Text
- GeoRef ID
- ISBN
- ISSN
- Issue
- Keyword (GeoRef Descriptor)
- Meeting Information
- Report #
- Title
- Volume
- Abstract
- Affiliation
- All
- Authors
- Book Series
- DOI
- EISBN
- EISSN
- Full Text
- GeoRef ID
- ISBN
- ISSN
- Issue
- Keyword (GeoRef Descriptor)
- Meeting Information
- Report #
- Title
- Volume
NARROW
GeoRef Subject
-
all geography including DSDP/ODP Sites and Legs
-
Africa
-
North Africa
-
Morocco
-
Tafilalt (1)
-
-
-
-
Arctic region
-
Greenland
-
East Greenland (1)
-
-
Svalbard
-
Spitsbergen (1)
-
-
-
Asia
-
Altai Mountains
-
Gorny Altai (1)
-
-
Altai Russian Federation
-
Gorny Altai (1)
-
-
Altai-Sayan region (1)
-
Far East
-
China
-
Guangxi China (1)
-
Sichuan China (1)
-
Xinjiang China
-
Junggar (1)
-
-
Yunnan China (2)
-
-
Laos (1)
-
-
-
Bathurst Island (2)
-
Caledonides (1)
-
Canada
-
Arctic Archipelago (10)
-
Eastern Canada
-
Maritime Provinces
-
New Brunswick (1)
-
Nova Scotia
-
Annapolis County Nova Scotia (1)
-
Kings County Nova Scotia (1)
-
-
-
Meguma Terrane (1)
-
Newfoundland and Labrador
-
Newfoundland
-
Port au Port Peninsula (1)
-
-
-
Ontario (1)
-
Quebec
-
Gaspe-Est County Quebec
-
Gaspe Quebec (1)
-
-
-
-
Nunavut
-
Boothia Peninsula (1)
-
Ellesmere Island (4)
-
Somerset Island (5)
-
-
Queen Elizabeth Islands
-
Ellesmere Island (4)
-
Parry Islands (7)
-
-
Western Canada
-
Northwest Territories (10)
-
-
-
Chaleur Bay (1)
-
Commonwealth of Independent States
-
Dniester River (1)
-
Russian Federation
-
Altai Russian Federation
-
Gorny Altai (1)
-
-
-
Ukraine
-
Podolia (3)
-
-
-
Cornwallis Island (7)
-
Europe
-
Baltic region
-
Estonia
-
Saaremaa (4)
-
-
-
Central Europe
-
Czech Republic
-
Bohemia
-
Prague Basin (1)
-
-
-
Poland (1)
-
-
Dniester River (1)
-
Pyrenees (1)
-
Southern Europe
-
Iberian Peninsula
-
Iberian Massif (1)
-
Ossa-Morena Zone (1)
-
Portugal (1)
-
Spain
-
Catalonian Coastal Ranges (1)
-
-
-
-
Ukraine
-
Podolia (3)
-
-
Western Europe
-
France
-
Aude France
-
Mouthoumet Massif (1)
-
-
-
Ireland
-
Mayo Ireland (1)
-
-
United Kingdom
-
Great Britain
-
England
-
Shropshire England (1)
-
Welsh Borderland (3)
-
-
Scotland (1)
-
Wales
-
Carmarthenshire Wales (1)
-
Pembrokeshire Wales (1)
-
Powys Wales (2)
-
South Wales (1)
-
Welsh Basin (1)
-
-
-
-
-
-
Herefordshire England (1)
-
Midlands (1)
-
North America
-
Appalachians
-
Southern Appalachians (1)
-
-
Basin and Range Province (1)
-
Gulf Coastal Plain (1)
-
North American Craton (1)
-
-
Prince of Wales Island (4)
-
South America
-
Argentina (1)
-
-
United States
-
Alabama
-
Jefferson County Alabama (1)
-
-
Maine
-
Somerset County Maine (1)
-
-
Nevada
-
Eureka County Nevada (1)
-
-
New York (2)
-
Oklahoma
-
Pontotoc County Oklahoma (1)
-
-
Virginia
-
Augusta County Virginia (1)
-
Highland County Virginia (1)
-
-
-
Willow Creek (1)
-
-
elements, isotopes
-
carbon
-
C-13/C-12 (3)
-
organic carbon (1)
-
-
isotope ratios (3)
-
isotopes
-
stable isotopes
-
C-13/C-12 (3)
-
O-18/O-16 (3)
-
-
-
metals
-
platinum group
-
iridium (1)
-
-
rare earths
-
neodymium (1)
-
-
-
oxygen
-
O-18/O-16 (3)
-
-
-
fossils
-
burrows (2)
-
Chordata
-
Vertebrata
-
Agnatha
-
Heterostraci (3)
-
-
Pisces
-
Acanthodii (1)
-
Chondrichthyes (1)
-
-
-
-
Graptolithina
-
Graptoloidea
-
Monograptina
-
Monograptus (2)
-
-
-
-
Hemichordata (2)
-
ichnofossils (3)
-
Invertebrata
-
Arthropoda
-
Chelicerata
-
Merostomata
-
Eurypterida (1)
-
-
-
Mandibulata
-
Crustacea
-
Ostracoda
-
Podocopida (1)
-
-
-
-
Trilobitomorpha
-
Trilobita (2)
-
-
-
Brachiopoda
-
Articulata
-
Orthida
-
Enteletacea (1)
-
-
Spiriferida
-
Atrypidae (1)
-
-
-
-
Bryozoa
-
Cystoporata (1)
-
-
Cnidaria
-
Anthozoa
-
Zoantharia
-
Rugosa (5)
-
Tabulata
-
Heliolitida
-
Heliolitidae
-
Heliolites (1)
-
-
-
-
-
-
-
Echinodermata
-
Crinozoa
-
Crinoidea (3)
-
-
-
Mollusca
-
Tentaculitida
-
Tentaculitidae
-
Tentaculites (1)
-
-
-
-
Porifera
-
Stromatoporoidea (3)
-
-
Protista
-
Radiolaria (1)
-
-
-
microfossils
-
Chitinozoa (1)
-
Conodonta
-
Icriodus (1)
-
Ozarkodina (1)
-
Panderodus (1)
-
-
-
palynomorphs
-
Chitinozoa (1)
-
miospores (2)
-
-
Plantae
-
algae
-
Rhodophyta (1)
-
-
Pteridophyta (1)
-
-
Pterobranchia (1)
-
thallophytes (1)
-
-
geochronology methods
-
paleomagnetism (2)
-
Sm/Nd (1)
-
U/Pb (2)
-
-
geologic age
-
Dalradian (1)
-
Paleozoic
-
Cambrian (1)
-
Carboniferous (1)
-
Devonian
-
Lower Devonian
-
Coeymans Formation (1)
-
Gedinnian (3)
-
Lochkovian (3)
-
Manlius Formation (1)
-
Pragian (3)
-
-
Old Red Sandstone (2)
-
-
Keyser Limestone (1)
-
lower Paleozoic
-
Cape Phillips Formation (2)
-
-
Ordovician (2)
-
Peel Sound Formation (1)
-
Permian (1)
-
Read Bay Formation (3)
-
Rondout Formation (1)
-
Silurian
-
Lower Silurian
-
Llandovery
-
Rhuddanian (1)
-
Telychian (1)
-
-
Wenlock
-
Homerian (2)
-
Sheinwoodian (1)
-
-
-
Middle Silurian
-
Roberts Mountains Formation (1)
-
-
Upper Silurian
-
Ludlow
-
Gorstian (1)
-
Ludfordian (3)
-
-
Pridoli (51)
-
-
-
-
Precambrian
-
upper Precambrian
-
Proterozoic
-
Neoproterozoic
-
Tonian (1)
-
-
-
-
-
-
igneous rocks
-
igneous rocks
-
volcanic rocks
-
basalts
-
tholeiite (1)
-
-
rhyolites (1)
-
-
-
-
metamorphic rocks
-
K-bentonite (1)
-
metamorphic rocks
-
metaigneous rocks (1)
-
metasedimentary rocks (1)
-
-
turbidite (1)
-
-
minerals
-
K-bentonite (1)
-
phosphates
-
monazite (1)
-
-
silicates
-
orthosilicates
-
nesosilicates
-
zircon group
-
zircon (3)
-
-
-
-
-
-
Primary terms
-
absolute age (3)
-
Africa
-
North Africa
-
Morocco
-
Tafilalt (1)
-
-
-
-
Arctic region
-
Greenland
-
East Greenland (1)
-
-
Svalbard
-
Spitsbergen (1)
-
-
-
Asia
-
Altai Mountains
-
Gorny Altai (1)
-
-
Altai Russian Federation
-
Gorny Altai (1)
-
-
Altai-Sayan region (1)
-
Far East
-
China
-
Guangxi China (1)
-
Sichuan China (1)
-
Xinjiang China
-
Junggar (1)
-
-
Yunnan China (2)
-
-
Laos (1)
-
-
-
biogeography (7)
-
Canada
-
Arctic Archipelago (10)
-
Eastern Canada
-
Maritime Provinces
-
New Brunswick (1)
-
Nova Scotia
-
Annapolis County Nova Scotia (1)
-
Kings County Nova Scotia (1)
-
-
-
Meguma Terrane (1)
-
Newfoundland and Labrador
-
Newfoundland
-
Port au Port Peninsula (1)
-
-
-
Ontario (1)
-
Quebec
-
Gaspe-Est County Quebec
-
Gaspe Quebec (1)
-
-
-
-
Nunavut
-
Boothia Peninsula (1)
-
Ellesmere Island (4)
-
Somerset Island (5)
-
-
Queen Elizabeth Islands
-
Ellesmere Island (4)
-
Parry Islands (7)
-
-
Western Canada
-
Northwest Territories (10)
-
-
-
carbon
-
C-13/C-12 (3)
-
organic carbon (1)
-
-
Chordata
-
Vertebrata
-
Agnatha
-
Heterostraci (3)
-
-
Pisces
-
Acanthodii (1)
-
Chondrichthyes (1)
-
-
-
-
clay mineralogy (1)
-
continental drift (1)
-
crust (1)
-
diagenesis (2)
-
Europe
-
Baltic region
-
Estonia
-
Saaremaa (4)
-
-
-
Central Europe
-
Czech Republic
-
Bohemia
-
Prague Basin (1)
-
-
-
Poland (1)
-
-
Dniester River (1)
-
Pyrenees (1)
-
Southern Europe
-
Iberian Peninsula
-
Iberian Massif (1)
-
Ossa-Morena Zone (1)
-
Portugal (1)
-
Spain
-
Catalonian Coastal Ranges (1)
-
-
-
-
Ukraine
-
Podolia (3)
-
-
Western Europe
-
France
-
Aude France
-
Mouthoumet Massif (1)
-
-
-
Ireland
-
Mayo Ireland (1)
-
-
United Kingdom
-
Great Britain
-
England
-
Shropshire England (1)
-
Welsh Borderland (3)
-
-
Scotland (1)
-
Wales
-
Carmarthenshire Wales (1)
-
Pembrokeshire Wales (1)
-
Powys Wales (2)
-
South Wales (1)
-
Welsh Basin (1)
-
-
-
-
-
-
faults (3)
-
geochemistry (3)
-
geochronology (1)
-
Graptolithina
-
Graptoloidea
-
Monograptina
-
Monograptus (2)
-
-
-
-
Hemichordata (2)
-
ichnofossils (3)
-
igneous rocks
-
volcanic rocks
-
basalts
-
tholeiite (1)
-
-
rhyolites (1)
-
-
-
intrusions (1)
-
Invertebrata
-
Arthropoda
-
Chelicerata
-
Merostomata
-
Eurypterida (1)
-
-
-
Mandibulata
-
Crustacea
-
Ostracoda
-
Podocopida (1)
-
-
-
-
Trilobitomorpha
-
Trilobita (2)
-
-
-
Brachiopoda
-
Articulata
-
Orthida
-
Enteletacea (1)
-
-
Spiriferida
-
Atrypidae (1)
-
-
-
-
Bryozoa
-
Cystoporata (1)
-
-
Cnidaria
-
Anthozoa
-
Zoantharia
-
Rugosa (5)
-
Tabulata
-
Heliolitida
-
Heliolitidae
-
Heliolites (1)
-
-
-
-
-
-
-
Echinodermata
-
Crinozoa
-
Crinoidea (3)
-
-
-
Mollusca
-
Tentaculitida
-
Tentaculitidae
-
Tentaculites (1)
-
-
-
-
Porifera
-
Stromatoporoidea (3)
-
-
Protista
-
Radiolaria (1)
-
-
-
isotopes
-
stable isotopes
-
C-13/C-12 (3)
-
O-18/O-16 (3)
-
-
-
magmas (1)
-
mantle (1)
-
metals
-
platinum group
-
iridium (1)
-
-
rare earths
-
neodymium (1)
-
-
-
metamorphic rocks
-
metaigneous rocks (1)
-
metasedimentary rocks (1)
-
-
North America
-
Appalachians
-
Southern Appalachians (1)
-
-
Basin and Range Province (1)
-
Gulf Coastal Plain (1)
-
North American Craton (1)
-
-
orogeny (1)
-
oxygen
-
O-18/O-16 (3)
-
-
paleoecology (7)
-
paleogeography (12)
-
paleomagnetism (2)
-
paleontology (11)
-
Paleozoic
-
Cambrian (1)
-
Carboniferous (1)
-
Devonian
-
Lower Devonian
-
Coeymans Formation (1)
-
Gedinnian (3)
-
Lochkovian (3)
-
Manlius Formation (1)
-
Pragian (3)
-
-
Old Red Sandstone (2)
-
-
Keyser Limestone (1)
-
lower Paleozoic
-
Cape Phillips Formation (2)
-
-
Ordovician (2)
-
Peel Sound Formation (1)
-
Permian (1)
-
Read Bay Formation (3)
-
Rondout Formation (1)
-
Silurian
-
Lower Silurian
-
Llandovery
-
Rhuddanian (1)
-
Telychian (1)
-
-
Wenlock
-
Homerian (2)
-
Sheinwoodian (1)
-
-
-
Middle Silurian
-
Roberts Mountains Formation (1)
-
-
Upper Silurian
-
Ludlow
-
Gorstian (1)
-
Ludfordian (3)
-
-
Pridoli (51)
-
-
-
-
palynomorphs
-
Chitinozoa (1)
-
miospores (2)
-
-
Plantae
-
algae
-
Rhodophyta (1)
-
-
Pteridophyta (1)
-
-
plate tectonics (3)
-
Precambrian
-
upper Precambrian
-
Proterozoic
-
Neoproterozoic
-
Tonian (1)
-
-
-
-
-
Pterobranchia (1)
-
reefs (2)
-
sea water (1)
-
sea-level changes (5)
-
sedimentary petrology (3)
-
sedimentary rocks
-
bone beds (1)
-
carbonate rocks
-
limestone
-
biomicrite (1)
-
-
-
chemically precipitated rocks
-
chert (1)
-
-
clastic rocks
-
arkose (1)
-
conglomerate (1)
-
mudstone (2)
-
radiolarite (1)
-
red beds (2)
-
sandstone (2)
-
shale (3)
-
siltstone (2)
-
-
-
sedimentary structures
-
biogenic structures
-
bioherms (1)
-
oncolites (1)
-
stromatolites (1)
-
-
-
sedimentation (4)
-
South America
-
Argentina (1)
-
-
stratigraphy (7)
-
tectonics (3)
-
thallophytes (1)
-
United States
-
Alabama
-
Jefferson County Alabama (1)
-
-
Maine
-
Somerset County Maine (1)
-
-
Nevada
-
Eureka County Nevada (1)
-
-
New York (2)
-
Oklahoma
-
Pontotoc County Oklahoma (1)
-
-
Virginia
-
Augusta County Virginia (1)
-
Highland County Virginia (1)
-
-
-
-
rock formations
-
Red Mountain Formation (1)
-
-
sedimentary rocks
-
calcrete (1)
-
flysch (1)
-
sedimentary rocks
-
bone beds (1)
-
carbonate rocks
-
limestone
-
biomicrite (1)
-
-
-
chemically precipitated rocks
-
chert (1)
-
-
clastic rocks
-
arkose (1)
-
conglomerate (1)
-
mudstone (2)
-
radiolarite (1)
-
red beds (2)
-
sandstone (2)
-
shale (3)
-
siltstone (2)
-
-
-
siliciclastics (1)
-
turbidite (1)
-
-
sedimentary structures
-
burrows (2)
-
sedimentary structures
-
biogenic structures
-
bioherms (1)
-
oncolites (1)
-
stromatolites (1)
-
-
-
-
sediments
-
siliciclastics (1)
-
turbidite (1)
-
-
soils
-
paleosols (1)
-
Pridoli
Two new eurypterids (Arthropoda, Chelicerata) from the upper Silurian Yulongsi Formation of south-west China
FIRST SYMBIOTIC ASSOCIATION BETWEEN HEDERELLOIDS AND RUGOSE CORALS (LATEST SILURIAN OF SAAREMAA, ESTONIA)
ABSTRACT Three Silurian basin fills, the Llandovery–Wenlock Croagh Patrick and Killary Harbour–Joyce Country successions and the Ludlow–Pridoli Louisburgh–Clare Island succession, overstep the tectonic contacts between elements of the Grampian (Taconic) accretionary history of the Caledonian-Appalachian orogeny in western Ireland. New U-Pb detrital zircon data from lower strata of these Silurian rocks provide insight into basin evolution and paleogeography. The shallow-marine Croagh Patrick succession unconformably overlies the Clew Bay Complex and the northern part of the Ordovician South Mayo Trough. Two samples have zircon populations dominated by Proterozoic grains typical of the Laurentian margin, with few younger grains. Up to 13% of the grains form a cluster at ca. 950–800 Ma, which is younger than known Grenville magmatism on the local Laurentian margin and older than known magmatism from Iapetan rifting; these may be recycled grains from Dalradian strata, derived from distal Tonian intrusions. The Killary Harbour–Joyce Country succession overlies the structural contact between the Lough Nafooey arc and the Connemara Dalradian block and records a transgressive-regressive cycle. Four samples of the Lough Mask Formation show contrasting age spectra. Two samples from east of the Maam Valley fault zone, one each from above Dalradian and Nafooey arc basement, are dominated by Proterozoic grains with ages typical of a Laurentian or Dalradian source, likely in north Mayo. One sample also includes 8% Silurian grains. Two samples from west of the fault overlie Dalradian basement and are dominated by Ordovician grains. Circa 450 Ma ages are younger than any preserved Ordovician rocks in the region and are inferred to represent poorly preserved arc fragments that are exposed in northeastern North America. Cambrian to late Neoproterozoic grains in association with young Ordovician ages suggest derivation from a peri-Gondwanan source in the late stages of Iapetus closure. The Louisburgh–Clare Island succession comprises terrestrial red beds. It unconformably overlies the Clew Bay Complex on Clare Island and is faulted against the Croagh Patrick succession on the mainland. The Strake Banded Formation yielded an age spectrum dominated by Proterozoic Laurentian as well as Ordovician–Silurian ages. Although the basin formed during strike-slip deformation along the Laurentian margin in Ireland and Scotland, sediment provenance is consistent with local Dalradian sources and contemporaneous volcanism. Our results support ideas that Ganderian continental fragments became part of Laurentia prior to the full closure of the Iapetus Ocean.
ABSTRACT Voluminous bimodal volcanic rocks of the Silurian (ca. 422–420 Ma) Dickie Cove Group in the Ganderia domain of northern New Brunswick, Canada, are subaerial units that were deposited in an extensional setting, with the mafic types corresponding to continental tholeiites. Felsic rocks are rhyolites with calc-alkaline affinities. They exhibit geochemical characteristics that are typical of A2-type felsic magmas, such as enrichments in the incompatible elements Zr, Nb, and Y, as well as high FeO*/(FeO* + MgO) and Ga/Al ratios. Their ε Nd ( t ) values are positive (+0.7 to +3.4) but lower than those of the associated basalts. Saturation thermometry has yielded average zircon crystallization temperature estimates for the rhyolites that are well above 900 °C. The geochemical data indicate that the felsic melts were likely sourced from heterogeneous Neoproterozoic lower crust and generated by dehydration melting triggered by heat derived from underplated mafic magma. Parent melts of the rhyolites underwent fractional crystallization in a complex magma chamber prior to eruption. The Nd isotopic data suggest that the lower crust of Ganderia is similar to that of Avalonia in northern mainland Nova Scotia, and that the two microcontinents shared a common Neoproterozoic history and origin as continental blocks rifted from neighboring parts of Gondwana. The tectono-magmatic setting of the Dickie Cove Group volcanic rocks is interpreted as being related to Pridolian, post-Salinic relaxation and slab breakoff, which generated volcanism initially constrained within the Chaleur zone of the Chaleur Bay synclinorium, a large domain of the northern Appalachians. This was followed later in the Pridolian by extensional collapse and widening of the area of magmatic activity, which then prograded into the Tobique zone farther to the southwest.
The Pridoli (Silurian) Lithostratigraphy and Biostratigraphy of Gorny Altai
Late Silurian zircon U–Pb ages from the Ludlow and Downton bone beds, Welsh Basin, UK
SYMBIOSIS OF RUGOSE CORALS WITH THE CYSTOPORATE BRYOZOAN FISTULIPORA PRZHIDOLENSIS IN THE PRIDOLI (LATEST SILURIAN) OF SAAREMAA, ESTONIA
Bringing planktonic crinoids back to the bottom: Reassessment of the functional role of scyphocrinoid loboliths
The stromatoporoid Habrostroma in the upper Silurian (uppermost Pridoli)–Lower Devonian (Lochkovian) of North America, and the paleobiogeographic significance of H . centrotum (Girty, 1895)
Silurian radiolarians from the Sepon Mine, Truong Son Terrane, central Laos and their palaeogeographic and tectonic significance
RUGOSAN EPIBIONTS ON VERTICAL STEMS FROM THE LUDLOW AND PRIDOLI OF SAAREMAA, ESTONIA (BALTICA)
A new Tolypelepidid (Agnatha, Heterostraci) from the Late Silurian of Poland
Wenlock and Pridoli (Silurian) crinoids from Saaremaa, western Estonia (Phylum Echinodermata)
Silurian flysch successions of Ellesmere Island, Arctic Canada, and their significance to northern Caledonian palaeogeography and tectonics
Carbon isotopic evidence for organic matter oxidation in soils of the Old Red Sandstone (Silurian to Devonian, South Wales, UK)
The graptolite, conodont and sedimentary record through the late Ludlow Kozlowskii Event (Silurian) in the shale-dominated succession of Bohemia
Carbon isotope stratigraphy across the Silurian–Devonian transition in Podolia, Ukraine: evidence for a global biogeochemical perturbation
A NEW LATE SILURIAN (PRIDOLIAN) NARAOIID (EUARTHROPODA: NEKTASPIDA) FROM THE BERTIE FORMATION OF SOUTHERN ONTARIO, CANADA—DELAYED FALLOUT FROM THE CAMBRIAN EXPLOSION
Charcoal in the Silurian as evidence for the earliest wildfire
Abstract Graptolites flourished from earliest Ordovician to Early Devonian, a time range of about 90 million years, and were widely distributed as marine benthic and planktonic colonial organisms around the world. They were diverse and rapidly evolving and, as such, make excellent “index fossils” for relative age-dating of their enclosing basinal rocks. Rarely, however, graptolites are beautifully preserved in their original three-dimensional form, and can be extracted from the enclosing rock for detailed study under scanning electron microscope. Such a unique preservation is pervasive in the latest Ordovician to latest Silurian rocks of the central Arctic Islands of Canada, presenting an opportunity to study their complex morphology and evolution, making the Arctic graptolite sequence unique in the world. The present study examines the isolated, uncompressed as well as flattened forms from the Ludlow and Pridoli (Upper Silurian) graptolites of the Arctic, recognizing 46 species of monograptids and retiolitids of which seven are described as new species or subspecies.