U.S. GEOLOGICAL SURVEY DIGITAL DATA SERIES DDS-6 RELEASE 3, 1995 STRATIGRAPHIC NOMENCLATURE DATABASES FOR THE UNITED STATES, ITS POSSESSIONS AND TERRITORIES Geologic Names Unit Lexicon (GNULEX) Compiled by Introduction to Gnulex :M. E. Mac Lachlan Western Interior region :M. E. Mac Lachlan, W. A. Bryant, T. W. Judkins Eastern region :E. D. Koozmin, R. C. Orndorff, M. L. Hubert, C. R. Murdock Western region :S. W. Starratt, J. R. Le Compte Geologic Names of the United States (GEONAMES) Compiled by C. R. Murdock, M. L. Hubert Database designer and programmer: C. C. Abston OVERVIEW This CD-ROM is the initial phase of a computerized lexicon of geologic- or stratigraphic-unit names (GNULEX) used in the United States, its possessions, and territories. The data are compiled from published geologic literature, and they may be sorted by geographic name, stratigraphic rank, age, geologic province or region, state, author, and specified keywords. Data have been collected in regional offices in Denver, Colorado; Menlo Park, California; and Reston, Virginia, of the U. S. Geological Survey. Each office maintains a computerized lexicon on a specific geographic area (GNULEX). GEONAMES, a concise database, is maintained by the Reston Office. It includes records on stratigraphic-unit names for all the states, possessions, and territories. Data are added to each system daily. Information on more than 10,000 stratigraphic-unit names from the GNULEX database and 20,000 unit names from the GEONAMES database are included on this CD-ROM. 1 This report has not been reviewed for U. S. Geological Survey editorial standards. This CD-ROM was produced in accordance with the ISO 9660 standard; however, it is intended for use only on DOS-based computer systems. The minimum system requirements to use the data with the software provided on the disk are as follows: DOS REQUIREMENTS . IBM or compatible personal computer . 640 kb RAM . EGA or VGA Color Monitor . MS or PC-DOS 4.0l or later . Microsoft MSCDEX version 2.1 or later . CD-ROM drive with ISO 9660 software driver . Hard disk drive To get started: DOS users should make the CD-ROM drive the active drive; then type INSTALL 2 INTRODUCTION TO GNULEX M. E. Mac Lachlan The Geologic Names Unit (GNU) offices (Denver, Colorado; Menlo Park, California; Reston, Virginia) of the U. S. Geological Survey (USGS) are compiling data on nomenclature applied to stratigraphic units used in the United States, its territories, and possessions into a computer-based system. The system is known collectively by the acronym GNULEX (Geologic Names Unit Lexicon). Staff members of GNU review USGS manuscripts early in the publication process for stratigraphic nomenclatural use. This new computer system was designed to provide each staff member with ready access to information published by the geologic profession; it may also serve as a tool for non-staff geologists to use. Previously, all the data collected by the GNU staffs for more than 100 years were maintained on a card-based system. Computerization has allowed for the inclusion of all information pertinent to the definition, modification, and use of stratigraphic unit names. The data on this disk can be searched by geographic name (Morrison), rank (Formation), geologic age (Jurassic, Late or Oxfordian), geologic province (Denver basin), State (CO), author (Eldridge), lithology (sandstone), and by preselected keywords. Data in GNULEX are presented in a style similar to that used in the lexicons published by the USGS (Wilmarth, 1938). The last complete published lexicon (Keroher and others, 1966) covered the years 1936-1960. Subsequently published lexicons have dealt only with definitions of newly named units. Although the quantity of geologic literature published since 1960 exceeds that of all years prior to 1960, a compilation of the modifications to all stratigraphic unit names has not been assembled since 1960. Most of the stratigraphic units in these databases are classified as lithostratigraphic, lithodemic, and allostratigraphic units by the 1983 North American Stratigraphic Code (NASC). Some chronostratigraphic (or geochronologic) units--Permian System (or Permian Period); Oxfordian Stage (or Oxfordian Age)--are also included. All the data have been collected from published geologic literature or from USGS reports in preparation. The latter are shown on this CD-ROM only by authors' last name and by an incomplete publication date--198_, 199_. Abstracts have been rarely cited because they usually do not adequately describe stratigraphic usage or change. Open-file reports and unpublished theses are not included in these databases because the definitions of many units first used or named in such reports are never published. The published literature limitations follow the recommendations of the stratigraphic codes (1933, 1962, 1970, 1983) published by the North American Commission on Stratigraphic Nomenclature - formerly (1933, 1962, 1970) called the American Commission on Stratigraphic Nomenclature. 3 The compilation process for this computer-based system has been started, but it is by no means complete. Although the history of usage for some units is complete, for others it is incomplete, and some units have no database record to date. In order to make the collection of data manageable for the staffs, the United States was divided into three regions--Eastern, Western Interior, and Western. Some duplication exists between the three regions due to the apolitical nature of stratigraphic units. The data on this CD-ROM were downloaded from the computers in the three GNU centers in March 1992. New information is added to the databases in each center daily. Updates of this first CD-ROM will be issued from time to time. STRATIGRAPHIC DATA The stratigraphic data are formatted to include information required for formally named units according to 1983 NASC and earlier codes. Many stratigraphic units used in the three regions were named prior to the 1983 Code and many prior to the first Code issued in 1933. The earlier names have become "formal" because of their long history of usage, and, in some cases, their commonly agreed upon definition. These earlier named units are included in the database, even those for which no one has ever declared intent to name, source of the geographic name, nor designated a type. Some informally named units are also in the database because of their stratigraphic importance. Some of these units have been named for specific geographic localities (Sunnyside). For other units, color terms or alphabetic designations are applied rather than place names. The initial letter of the informal name may be a capital letter--Mahogany, J, X, but the initial letter of the second part of the unit name, a lithic or informal designation, such as ledge, bed, zone, sand, bentonite, marker, layer, is always lowercase. Whenever the same geographic name or other designated name is applied to two or more stratigraphic units, a letter designation follows the name. In order of publication date, capital letters A, B, etc., are assigned to formal units and lowercase letters a, b, etc. to the informal units. For example: Wanakah A is a Devonian formation in New York that was first used by Grabau in 1917; Wanakah B is a Jurassic formation in New Mexico, Colorado, Utah, and Arizona that was named by Burbank in 1930. 4 UNIT RECORDS Data for each stratigraphic unit are placed in a standardized format that is used in the three GNU offices. For purposes of this discussion the data are segregated into two types of information--a summary of present-day usage and the historical record. The Historical record traces the basic definition of the unit, and all modifications to the definition. In addition, other information considered important to the general understanding of a stratigraphic unit is also included. Each historical record has a publication reference and a synopsis of data from the publication that pertains to the specific stratigraphic unit. The database may be searched for stratigraphic units having particular characteristics referred to as "search categories." The search categories are selected from the listing in the main menu. Once a category is selected, a pop-up alphabetized list will appear listing the specific terms available in that category in the database. The categories of rank, geologic age, geologic province, and State are associated with summary information. The synopses that accompany each reference can have as many as three search categories (keyword, lithology, geologic province) listed above the text. The first listed is the keyword(s), which gives the reason(s) for inclusion of a specific reference in the database. These reasons were chosen from those listed in the 1983 NASC (article 3) that apply to the naming, revising, abandoning, or reinstating of formally named geologic units. The term "redescribed," however, is used in preference to the word "redefined" (NASC, article 18). Other types of information pertinent to the general understanding of each unit have also been categorized as reasons for including a report in the database, and they also may be used for searching the database. These include: age modified, age modified locally, areal limits, biostratigraphic dating, figure (that is to say--figures available in the database), isotopic dating, overview, paleomagnetics, redescribed (or change of lithologic rank term), and selection of a principal reference or of a reference locality. The two other categories associated with the synopses are used to identify the geologic province in which the unit occurs in the specific report, and the lithology. Geologic province names and boundaries follow maps by Meyer, 1974, or Meyer, Wallace, and Wagner, 1991. Lithology is given only with publications in which a unit was named, redescribed, assigned a principal reference or reference section, and in some overview papers. 5 REFERENCES American Commission on Stratigraphic Nomenclature, 1933, Classification and nomenclature of rock units: Geological Society of America Bulletin, v. 44, p. 423-459. American Commission on Stratigraphic Nomenclature, 1962, Code on stratigraphic nomenclature: American Association of Petroleum Geologists Bulletin, v. 43, no. 5, p. 645-665. American Commission on Stratigraphic Nomenclature, 1970, Code of Stratigraphic Nomenclature: American Association of Petroleum Geologists, Tulsa, OK, 22p. Burbank, W.S., 1930, Revision of geologic structure and stratigraphy in the Ouray district of Colorado, and its bearing on ore deposition: Colorado Scientific Society Proceedings, v. 12, no. 6, p. 151-232. Grabau, A.W., 1917, Age and stratigraphic relations of the Olentangy shale of central Ohio, with remarks on the Prout limestone and so-called Olentangy shales of Northern Ohio: Journal of Geology v. 25, p. 337-343. Keroher, G.C., and others, 1966, Lexicon of geologic names of the United States for 1936-1960: U.S. Geological Survey Bulletin 1200, pt. 1, A-F, p. 1-1448; pt. 2, G-O, p. 1449-2886; pt. 3, P-Z, p. 2887-4341. Meyer, R.F., ed, 1974, AAPG-CSD geological provinces Code map (revised): American Association of Petroleum Geologists, Tulsa, 1 sheet, scale 1:500,000. Meyer, R.F., Wallace, L. G., and Wagner, F. J., Jr., 1991, AAPG-CSD geological provinces code map: American Association of Petroleum Geologists Bulletin, v. 75, no. 10, p. 1644-1651. North American Commission on Stratigraphic Nomenclature, 1983, North American Stratigraphic Code: American Association of Petroleum Geologists Bulletin, v. 67, no. 5, p. 841-875. Wilmarth, M.G., 1938, Lexicon of geologic names of the United States (including Alaska): U. S. Geological Survey Bulletin 896, pt. 1, A-L, p. 1-1244; pt. 2, M-Z, p. 1245-2396. 6 WESTERN INTERIOR REGION GNULEX Compiled by M. E. Mac Lachlan, W. A. Bryant, and T. W. Judkins STRATIGRAPHIC DATA The summary information on each stratigraphic unit appears in a specific order. Asterisks are used throughout this database to indicate usage in USGS-authored reports. UNIT NAME. Formal names: refers only to the geographic (Entrada) part of the unit name. Informal names: refer only to the geographic part of name, or the alphabetic or color designation. RANK (OR RANKS) or descriptive lithic term. List shows terms applied to the unit at the present time (March 1992). TYPE (LOCALITY, SECTION, OR AREA). Stated as described by author. Supplementary information may be added by the compiler. "Type" is never arbitrarily assigned by compiler if author does not clearly designate one. Statement "None designated" is used if no type has ever been designated. Statement "Not evaluated to date" applied to units whose naming or first-published-use papers have not been evaluated for this database. INDEX. Brief listing in historic order of all data presently in computer system by keyword (see Glossary for listing and definition) or by some other general statement such as "Divided into..." followed in parenthesis by author(s) and year of publication. GEOLOGIC AGE. Listed in order of decreasing age by geologic epoch (Triassic, Late) and, when known, stage (Norian). Larger divisions of geologic time - periods (Cretaceous), erathem (Mesozoic), eonothem (Phanerozoic) are shown only for those units whose age assignments are very generally known. For sorting purposes, the term "Quaternary" is added to all units of Pleistocene or Holocene age, the term "Tertiary" to all units of Paleocene, Eocene, Oligocene, Miocene, or Pliocene age and the term "Precambrian" to all units of Proterozoic or Archean age. 7 GEOLOGIC PROVINCE. Assignment follows location within the American Association of Petroleum Geologists Committee on Statistics of Drilling (AAPG-CSD), a geological provinces code map (Meyer, 1974) for the Phanerozoic units, or within one or several of the general regions (see Glossary) for the Precambrian units. Geochronologic terms (for example, Jurassic) that are recognized over many geologic basins or provinces in North America and other Continents are assigned the term "Cosmopolitan." STATES. Shown by U.S. Postal Service abbreviations. Part of State shown in parenthesis. The geochronologic units such as Cretaceous that extend over large areas in some instances beyond the United States are assigned the term "Cosmopolitan." The term North America is assigned to units known over large parts of the North American Continent -- for example, Wasatchian land mammal age. Some units in this database extend north into CN (Canada), AT (Alberta), BC (British Columbia), or south into MX (Mexico). Some units were named or first described for occurrences in CN (Ashern Formation) or MX (Ojinaga Formation). However, this lexicon should not be considered to be a lexicon of stratigraphic nomenclature for either Canada or Mexico. Between the Summary and the Historical record, a listing of references to the specific stratigraphic unit in the database will appear. The listing includes year of publication, author(s) names, the stratigraphic unit name as used in the report, and the keyword(s) that explain the reason for including the report in GNULEX. The Historical record includes (1) the reference, (2) the full stratigraphic unit name--geographic name and rank or descriptive lithic term as used by the author, (3) the keyword, lithology, geologic province, the initials of the staff member who reviewed the publication and the date the synopsis was entered into the database, and (4) a synopsis of information in the publication that pertains to the specific stratigraphic unit. The synopsis is written in a very telegraphic style. All sentences that start with a verb have the stratigraphic unit name as their subject. The statement "In review as of March 30, 1992" is used in place of a synopsis with reports written by USGS authors for another organization that were not published at the time the data on this disk was downloaded. ACKNOWLEDGMENTS The following individuals (initials in parentheses) have made major contributions to the database: W. A. Bryant (wab), P. T. Hayes (pth), T. W. Judkins (twj), R. A. Lucas (ral), M. E. Mac Lachlan (mem), W. J. Mapel (wjm), H. I. Saperstone (his), L. M. Stone (lms). Ollie Williams provided the database and computer assistance. 8 GLOSSARY PRECAMBRIAN REGIONS The application of province and basin names used to show the extent of Phanerozoic units is not suitable for Precambrian units of the Western Interior region. The boundaries selected for the Precambrian regions based on the advice of J. C. Reed, P. K. Sims, J. E. Harrison, Z. E. Peterman, and M. R. Reynolds of the USGS generally follow the features shown on the Precambrian geology map of Reed (1987, fig. 1). The boundaries are cumbersome to describe without a map. The following region names and their boundaries are: MIDCONTINENT REGION. West of the Appalachian region, south of the Lake Superior region, and east of the Rocky Mountains of MT, Bighorn Mountains and Laramie Range of WY, Front Range of CO, east of the Sangre de Cristo Range of CO and NM south into TX east of the Sacramento and Guadalupe Mountains. LAKE SUPERIOR REGION. Includes the northern peninsula of MI, most of WI, and all of MN, easternmost ND, central and eastern SD, northeast NE, central and northern IA. NORTHERN ROCKY MOUNTAIN REGION. West of the Midcontinent region, south of the Canadian border, to the southern edge of the Laramie Range, Medicine Bow Mountains and Sierra Madre of WY, and north of the Uinta Mountains. The western limit is the approximate west edge of the Archean crust, a line drawn across southeast WA, western ID, and northern NV. SOUTHERN ROCKY MOUNTAIN REGION. South of the Northern Rocky Mountain region, west of the Midcontinent region to the southern limit of the Sangre de Cristo Mountains. The southern border in AZ is the Mogollon Rim. The west limit is the Wasatch uplift of UT. SOUTHWESTERN BASIN-AND-RANGE. South of the Mogollon Rim and Sangre de Cristo Mountains, north of Mexico, and west of the Midcontinent region. Includes the southern tip of NV. GREAT BASIN PROVINCE. Area west of the Wasatch uplift in UT and east of the approximate western edge of the Archean crust in central NV. Lies between the Northern Rocky Mountain region on the north and the Southwestern Basin-and-Range region on the south, and the Southern Rocky Mountain region on the east. 9 KEYWORDS. Reason(s) for inclusion of a report in the Western Interior area GNULEX. ABANDONED. Justification for abandonment and replacement name(s) included. Not used for restriction of areal extent. AGE MODIFIED. Age changed, age refined, stratigraphic position dating; evidence for age change stated if such information included by author. AGE MODIFIED LOCALLY. Local, rather than general or regional, age change. AREAL LIMITS. Geographic extent, provisional extent, or limitations on areal extent on the surface and(or) in the subsurface. Presence of geologic or isopach maps noted. BIOSTRATIGRAPHIC DATING. Age determinations based on recognition of index fossils or biozonal assignment; does not include mere mention of fossils. FIGURE. Shows correlations of stratigraphic units or divisions of geologic stages or systems that have been constructed by staff members without benefit of graphics software. FIRST USED. First publication to use a stratigraphic unit name, but one in which intent to name is not stated. Applied only to reports that include substantive information on the unit. Casual mention on a chart or figure, or in an abstract not categorized as a valid first publication. ISOTOPIC DATING. Numerical age determined from isotopic ratios, fission tracks, and other age-related phenomena. NAMED. Intent to name, call, designate, or propose a new name and clearly stated as "here" or "in this report." Exact location and description of type (section, locality, or area) and derivation of geographic name applied to the unit included. Pertinent information on description of lithology, contacts, areal extent, age assignment, figures, etc. summarized. NOT USED. Unit name not used in this report, but it is not abandoned. Reason for non-use included if stated. OVERVIEW. Detailed local or regional information of one or more of the following: lithology; fossils; mappability or occurrence; measured sections; source; environment of deposition; thickness; presence of geologic, isopach, or areal extent maps; cross sections; correlation or history-of-use charts or other figures noted. PALEOMAGNETICS. Determinations based on remanent-magnetic properties; most commonly polarity (normal or reversed), but may include dipole-field-pole position, non-dipole component, and field intensity. 10 PRINCIPAL REFERENCE (SECTION, LOCALITY, OR AREA). Exact location as given by author. Supplementary information may be added by compiler. Description of lithology, contacts, and thickness summarized. Measured section(s) summarized. Presence of pertinent figures noted. REDESCRIBED. Descriptive lithic term or rank term changed because of change in dominant lithology requiring application of a different rank term. REFERENCE (SECTION, LOCALITY, OR AREA). Exact location as given by author. Description of rocks at reference section(s) included if space permits. Presence of pertinent figures noted. REINSTATED. A name abandoned for reasons that seemed valid at the time but that are later found to be erroneous may be reinstated; reason for reinstatement included, if stated by author. REVISED. Change in stratigraphic rank, contacts, affiliated units (divided into units of lesser rank), assigned to a unit of higher rank, new name applied to rocks below or above, spelling of geographic name changed. 11 EASTERN REGION GNULEX Compiled by Elizabeth D. Koozmin, Randall C. Orndorff, Marilyn L. Hubert, and Cynthia R. Murdock STRATIGRAPHIC DATA SUMMARY LIST RECORD (Asterisks (*) are used to indicate usage by the U.S. Geological Survey.) UNIT NAME. Refers only to the geographic or descriptive part of the unit name. Duplicate usage of a name is indicated by A, B, C, etc, for formal names, and by {a}, {b}, {c}, etc., for informal names. Asterisks have been omitted from this field in the Eastern Region database. RANK. Shows all stratigraphic ranks applied to the unit at the present time (March 1994). Informal rank terms are lowercase. TYPE LOCALITY (SECTION OR AREA). Stated as described by author. Information followed by author'(s) last name and date of publication. If no type section or locality has been designated, the general area of occurrence and naming feature are given, if known. INDEX. The index portion of the unit summary contains three types of information. USAGE. Variations in usage and the states in which those usages apply are listed here. "No current usage" implies that a name has been abandoned or that it has fallen into disuse. A usage preceded by a slash (/) indicates that it in some way violates the 1983 North American Stratigraphic Code. This violation may be explained within brackets ([]). SUBUNITS. If the unit has been subdivided, those subunits and the states in which they are used are listed here. HISTORY. A brief list of important papers, beginning with the first use or naming paper, is given here. Subsequent papers that have had significant impact on the definition or age of the unit or that supply a good description of the unit are also listed. Not all of these references may be in the database at this time. 12 AGE INFORMATION. Geologic ages are listed in order of decreasing age by Epoch and, when known, by Stage. Larger divisions of geologic time are shown only for those units whose age assignments are very generally known. However, for sorting purposes, the terms Precambrian, Tertiary, and Quaternary have been added where they apply. PROVINCE INFORMATION. Provinces are based on the American Association of Petroleum Geologists Committee on Statistics of Drilling (AAPG-CSD) maps (Meyer, 1974; Meyer and others, 1991). The new provinces outlined on the 1991 map have been used for recent entries. Also included are the names of the Mesozoic basins (for the Newark Supergroup units). "Caribbean region" encompasses Puerto Rico and the U.S. Virgin Islands. Precambrian region names are not used. STATE INFORMATION. States are listed by the U.S. Postal Service 2-letter abbreviations. CAN is used for units extending to or from Canada. The type locality state is shown first. Following the Summary list are numbered references currently in the database. You may choose to view one or all of these. HISTORICAL RECORD REFERENCE. Author key, author(s), date of publication, and full citation given for accompanying remark. REMARKS. A remarks record includes the geologic name, keywords, reviewer's initials, date the report was reviewed, and a brief synopsis. Each remark begins with the geologic name as it is used in the above report. An asterisk after the name indicates that the report was authored or co-authored by a USGS scientist. Following this are one or more keywords that briefly state the significance of the report. These are followed by the area of the report and, in some cases, the lithologies by which the unit can be identified. Reviewer initials and the date of entry precede the synopsis. In the interest of accuracy, abstracts generally adhere closely to the wording used in the report, but the style in most cases is telegraphic. 13 ACKNOWLEDGMENTS The following people have made significant contributions to the data file: Claire B. Davidson (cbd), Edward G. Hasser (egh), Marilyn L. Hubert (mlh), Elizabeth D. Koozmin (edk), Gwendolyn W. Luttrell (gwl), Cynthia R. Murdock (crm), Randall C. Orndorff (rco), and Warren L. Peterson (wlp). GLOSSARY ABANDONED. Implies that author has clearly stated in this report that the unit name should be abandoned or is replaced by another name. AGE MODIFIED. Used when age of unit has been changed or refined either regionally or locally. AREAL LIMITS. Implies geographic extension or restriction of a unit name. Also used when report discusses known extent of unit. BIOSTRATIGRAPHIC DATING. Used when age determinations are based on recognition of index fossils or biozonal assignment. FIRST USED. Applied when name is introduced but not formally proposed, or when a name has been proposed in an unpublished thesis or open-file report. ISOTOPIC DATING. Used when report includes age determined from isotopic ratios, fission tracks, and other age-related phenomena. NAMED. Reserved for formal proposals in recognized scientific media. Intent to name usually stated and type locality and adequate description of unit supplied. NOT USED. Implies unit name has been discarded by author, but not formally abandoned. OVERVIEW. Used when report supplies detailed local or regional information on the unit. Also used to show continued use of an old, but seldom used name. PRINCIPAL REFERENCE. Used only when principal reference is designated. Generally applies to units for which no type locality has been previously designated. REDESCRIBED. Used when unit composition is changed due to geochemical analyses, detailed mapping, etc. May affect rank or lithologic term. REFERENCE. Used in addition to the type or principal reference section and provides further thickness and lithological information. 14 REINSTATED. Reserved for reinstatement of abandoned names. Original definition may be accepted or modified by report. REVISED. Applied when stratigraphic rank, contacts, affiliations, or spelling of name has been changed. 15 WESTERN REGION GNULEX Compiled by Scott W. Starratt and J. R. Le Compte STRATIGRAPHIC DATA Information from some abstracts is included in this database. Dissertation Abstracts is used as a source for the first use of newly named units. Other published abstracts are used as source information for the modification of the age assignment of stratigraphic units. Geologic age. Western area GNULEX cannot be sorted by stage name, nor by the general age terms "Quaternary," "Tertiary," and "Precambrian" if a geochronologic term of lesser rank (for example, Paleocene) has been applied to the geologic unit name. Geologic province. Precambrian units have not been assigned to one of the Precambrian regions (see Western Interior area Glossary). ACKNOWLEDGMENTS The following people (initials in parentheses) made significant contributions to the Western area GNULEX: Cindy Barclay (czb), Bill Fedasko (bzf), Louis A. Fraticelli (laf), Virginia A. Langenheim (val), Aida Larson (arl), James R. Le Compte (jrl), C. Dean Rinehart (cdr), Patrick Showalter (pks), Scott W. Starratt (sws), Sean Murphy-Stone (sms). The initials above each abstract refer to the individual who wrote the abstract. They are followed by the date of entry into the database. 16 GLOSSARY KEYWORDS. Gives reason(s) for inclusion of a report in the Western region GNULEX. ABANDONED. Reason for abandonment and replacement name(s) included. Not used for restriction of areal extent. ADOPTED. A USGS author may adopt a unit name for USGS usage by citation [i.e., explicit statement of intent to NAME a new unit or ADOPT the previously published unit usage of another (non- USGS) author] in a formal publication. It is the author's responsibility to determine whether unit as previously defined (by a non-USGS author) is properly defined (by the NASC); if it has not been sufficiently defined, additional information must be included to conform with the NASC and USGS standards. AGE MODIFIED. Age changed, age refined, evidence for age change stated if such information included by author. AREAL LIMITS. Geographic extent, province assignment, or limitations on areal extension the surface and(or) in the subsurface. BIOSTRATIGRAPHIC DATING. Fossils are specified where possible. FIRST USED. This keyword is used when the unit name appears in print prior to the unit actually being formally named. This commonly occurs when the name appears in a figure with no supporting text. Information from theses has also been included, IF the unit name has appeared in Dissertation Abstracts. ISOTOPIC DATING. Dating technique and error values are specified where possible. Conversion to currently accepted decay ratios is noted. NAMED. A unit is considered to be named when it has been defined (as described by the NASC after 1933) and published in an appropriate publication. A unit can be named either by a USGS or a non-USGS author. A unit named (and thereby adopted) by a USGS author is followed by an "*" (Monterey*). Note: Prior to 1933, author(s) intent, either overt or implied, to formally name units is considered to be grounds for recognition of such action. NAMED BUT NOT ADOPTED. Defined and published as above, but by a non-USGS author. When such units are cited in a report, they are followed by a reference citation [for example, Blue Canyon Formation of Jones (1990) or Blue Canyon Formation (Jones, 1990)]. NOT USED. Author states that one unit name is used in preference to another. Reason is usually given. 17 OVERVIEW. Used when the author includes detailed information in a number of different keyword categories. PALEOMAGNETIC DATING. Self-explanatory. PRINCIPAL REFERENCE. Includes location of principal reference section, locality, or area, as well as all other reference sections, localities, or areas. REDESCRIBED. Lithology is described in detail and (or) changed. A list of currently used lithologies is included. REFERENCE. Attributes of reference section(s). REINSTATED. Abandoned unit is reinstated; must be specifically stated as such in text. REVISED. Change in stratigraphic rank, change of contacts, affiliated units (divided into units of lesser rank), assigned to a unit of higher rank, new name applied to rocks below or above, and spelling of geographic name changed. 18 GEONAMES Compiled by C. R. Murdock and M. L. Hubert The GEONAMES database is an annotated index lexicon of formal geologic nomenclature of the United States, its terri- tories and possessions. The first version was published in 1981 (Swanson, R.W., Hubert, M.L., Luttrell, G.W., and Jussen, V.M., 1981: U.S. Geological Survey Bulletin 1535, 643 p.). GEONAMES is updated on a regular basis and has been made available twice in recent years as open-file reports on 5 1/4-inch diskettes (Luttrell, G.W., Hubert, M.L., and Murdock, C.R., 1988: U.S. Geological Survey Open-File Report 88-0044; 1990: U.S. Geological Survey Open-File Report 90-0466.) The CD-ROM version of GEONAMES contains more than 30,000 records relating to more than 18,000 names. Units may have more than one usage, occur in more than one state, or span more than one age, therefore requiring more than one record. Data have been entered in the nine fields explained below. Each record is 123 characters in length. Records may be retrieved by geologic name, State, geologic age, geologic province, or lithology. Selected records may be viewed on the screen in the original coded version or in a longer translated version that supplies, for convenience, a translation of the numerical codes and abbreviations. Selections, including the entire database, may be written to a file to be printed after exiting the program. (The entire database is approxi- mately 800 printed pages.) Included within brackets ([]) in the "Definition of Fields" is the length of each field for users who may wish to load the data into a commercial database manager. DEFINITION OF FIELDS. The formats and codes used in the fields are explained below. Fields 6, 7, 8, and 9 are used only once for each unit, as this information pertains to its type locality and original reference. Records are alphabetical, first by unit name and second by State abbreviation. If more than one age is associated with a unit, these records are in ascending (youngest to oldest) order. 19 FIELD 1 [4]. LOCATION. The U.S. Postal Service 2-letter abbreviations are used to identify the State, territory, or possession in which the unit is located. AL Alabama NH New Hampshire AK Alaska NJ New Jersey AZ Arizona NM New Mexico AR Arkansas NY New York CA California NC North Carolina CO Colorado ND North Dakota CT Connecticut OH Ohio DC District of Columbia OK Oklahoma DE Delaware OR Oregon FL Florida PA Pennsylvania GA Georgia RI Rhode Island HI Hawaii SC South Carolina ID Idaho SD South Dakota IL Illinois TN Tennessee IN Indiana TX Texas IA Iowa UT Utah KS Kansas VT Vermont KY Kentucky VA Virginia LA Louisiana WA Washington ME Maine WV West Virginia MD Maryland WI Wisconsin MA Massachusetts WY Wyoming MI Michigan MN Minnesota CI Caroline Islands MS Mississippi GU Guam MO Missouri MR Mariana Islands MT Montana PR Puerto Rico NE Nebraska SA Samoa NV Nevada VI Virgin Islands 20 FIELD 2 [4]. GEOLOGIC AGE. The geologic age at the time of the last update is represented by the 3-digit code devised by the AAPG Committee on Standard Stratigraphic Coding. ERA PERIOD EPOCH OR CODE PROVINCIAL SERIES Cenozoic 100 late 101 middle 104 early 107 Quaternary 110 Holocene 111 Pleistocene 112 Tertiary 120 Pliocene 121 Miocene 122 Oligocene 123 Eocene 124 Paleocene 125 Mesozoic 200 late 201 middle 204 early 207 Cretaceous 210 Late 211 Early 217 Jurassic 220 Late 221 Middle 224 Early 227 Triassic 230 Late 231 Middle 234 Early 237 Paleozoic 300 late 301 middle 304 early 307 Permian 310 Late 311 Early 317 21 Pennsylvanian 320 Late 321 Middle 324 Early 327 Mississippian 330 Late 331 Early 337 Devonian 340 Late 341 Middle 344 Early 347 Silurian 350 Late 351 Middle 354 Early 357 Ordovician 360 Late 361 Middle 364 Early 367 Cambrian 370 Late 371 Middle 374 Early 377 Precambrian (informal) 400 Proterozoic 401 Late 410 Middle 420 Early 430 Precambrian (informal) 400 Archean 404 Late 440 Middle 450 Early 460 pre-Archean 407 22 FIELD 3 [1,67]. NAME. The geologic name consists of a geographic name combined with a rank or descriptive term. A comma separates the two parts of the name. If a unit is part of a higher ranking unit, the name of that unit follows in parentheses. A slash (/) preceding a name indicates a violation of the North American Stratigraphic Code (for instance, a name may have been used previously in the same area, or a rank term may have been used improperly or may have been omitted). [When loading files into a database manager, the slash should be placed in a separate field so that it will not interfere with the alphabetizing of geologic names.] Only current usage is given for each unit. Brackets enclose intended rank if omitted in the naming reference. Abbreviations for common lithologies and rank terms are used. Other words may be abbreviated where necessary to reduce the unit name to the 65- character limitation. Duplicate names are tagged with bracketed letters so that they can be easily identified and separated by the computer. In most cases these letters correspond to those assigned to the units in GNULEX. An asterisk (*) is found at the end of a unit name if the line entry is based on usage in a U.S. Geological Survey report. 23 FIELD 4 [14]. LITHOLOGY. The principal lithology of the unit at the type section is given. ADM adamellite GAB gabbro NRT norite AGL agglomerate GLC glauconite NVC novaculite ALV alluvium GN gneiss OBS obsidian AMP amphibolite GNS greenstone OOL oolite AND andesite GR granite PCL pyroclas- tics ANH anhydrite GRD granodiorite PHL phyllite ANR anorthosite GRNL granulite PHS phosphate ARG argillite GSOL geosol PMC pumice ARK arkose GVL gravel POR porphyry ASH ash GYK graywacke QTZ quartzite BAS basalt GYP gypsum QZ quartz BNT bentonite HNF hornfels QZD quartz diorite BRC breccia IG igneous rock QZM quartz monzonite CARB carbonate IGNM ignimbrite RDBD redbed CGL conglomerate INTR intrusive rock RHY rhyolite CH chert LAT latite SCH schist CHK chalk LOS loess SD sand CL clay LS limestone SED sedimentary rock CLS claystone LV lava SH shale COAL coal MBL marble SL slate CST clastic rock MBNT metabentonite SRP serpentinite DAC dacite MCK muck ST silt DBS diabase MD mud STS siltstone DMC diamict MET metamorphic rock SYN syenite DOL dolomite, dolostone MGM migmatite TF tuff DRT diorite MGYK metagraywacke TJM trondhje- mite DRF drift MIG metaigneous rock TL till DTM diatomite MNZ monzonite TNL tonalite EVP evaporite MRL marl TRC trachyte FE iron-formation MS mudstone ULTM ultramafic rock FELS felsite MSED metasedim. rock VOL volcanic rock FGL fanglomerate MVOL metavolcanic rock VSED volcanic sed. 24 FIELD 5 [6]. GEOLOGIC PROVINCE. The 3-digit geologic province code devised by the AAPG Committee on Statistics of Drilling (CSD) is used. 100 New England province 110 Adirondack uplift 120 Atlantic Coast basin 130 South Georgia-North Florida sedimentary province 140 South Florida province 150 Piedmont-Blue Ridge province 160 Appalachian basin 200 Warrior basin 210 Mid-Gulf Coast basin 220 Gulf Coast basin 230 Arkla basin 240 Desha basin 250 Upper Mississippi embayment 260 East Texas basin 300 Cincinnati arch 305 Michigan basin 310 Wisconsin arch 315 Illinois basin 320 Sioux uplift 325 Iowa shelf 330 Lincoln anticline 335 Forest City basin 340 Ozark uplift 345 Arkoma basin 350 South Oklahoma folded belt province 355 Chautauqua platform 360 Anadarko basin 365 Cherokee basin 370 Nemaha anticline 375 Sedgwick basin 380 Salina basin 385 Central Kansas uplift 390 Chadron arch 395 Williston basin 400 Ouachita tectonic belt province 405 Kerr basin 410 Llano uplift 415 Strawn basin 420 Fort Worth syncline 425 Bend arch 430 Permian basin 435 Palo Duro basin 440 Amarillo arch 445 Sierra Grande uplift 25 450 Las Animas arch 455 Las Vegas-Raton basin 460 Estancia basin 465 Orogrande basin 470 Pedregosa basin 475 Basin-and-Range province 500 Sweetgrass arch 505 Montana folded belt province 510 Central Montana uplift 515 Powder River basin 520 Big Horn basin 525 Yellowstone province 530 Wind River basin 535 Green River basin 540 Denver basin 545 North Park basin 550 South Park basin 555 Eagle basin 560 San Luis basin 565 San Juan Mountain province 570 Uinta uplift 575 Uinta basin 580 San Juan basin 585 Paradox basin 590 Black Mesa basin 595 Piceance basin 600 Northern Cascade Range-Okanagan province 605 Eastern Columbia basin 610 Idaho Mountains province 615 Snake River basin 620 Southern Oregon basin 625 Great Basin province 630 Wasatch uplift 635 Plateau sedimentary province 640 Mojave basin 645 Salton basin 650 Sierra Nevada province 700 Bellingham basin 705 Puget Sound province 710 Western Columbia basin 715 Klamath Mountains province 720 Eel River basin 725 Northern Coast Range province 730 Sacramento basin 735 Santa Cruz basin 740 Coastal basins 745 San Joaquin basin 750 Santa Maria basin 755 Ventura basin 760 Los Angeles basin 765 Capistrano basin 26 800 Southeastern Alaska provinces 810 Gulf of Alaska basin 815 Copper River basin 820 Cook Inlet basin 825 Alaska Peninsula province 830 Yukon-Porcupine province 840 Koyukuk province 845 Bristol Bay basin 846 Aleutians Islands 860 Selawik Lowland basin 880 Interior Lowlands basin 884 Brooks Range province 885 Southern Foothills province 886 Northern Foothills province 890 Arctic Coastal Plains province 982 Sumagin shelf 984 Kodiak Island FIELD 6 [10]. THICKNESS. Thickness at the type section, in meters, rounded to the second significant figure is shown. Where this information is unavailable, the maximum thickness known regionally is given, if known. FIELD 7 [6]. TYPE LOCALITY. One of nine parts of the State in which the type section, locality, or area of a unit is located. Each State is divided into nine parts, designated NW, NC, NE, WC, C, EC, SW, SC, SE, by dividing its maximum latitudinal and longitudinal dimensions by three. Canada and Mexico are designated by CAN and MEX. 27 FIELD 8 [4]. REFERENCE. The letters A through G refer to the volume of the Lexicon of Geologic Names in which a name was first described: A. Wilmarth, M.G., 1938, Lexicon of geologic names of the United States: U.S. Geological Survey Bulletin 896, 2 v. B. Wilson, Druid, and others, 1957, Geologic names of North America introduced in 1936-1955: U.S. Geological Survey Bulletin 1056-A, 405 p. C. Keroher, G.C., and others, 1966, Lexicon of geologic names of the United States for 1936-1960: U.S. Geological Survey Bulletin 1200, 3 v. D. Keroher, G.C., 1970, Lexicon of geologic names of the United States for 1961-1967: U.S. Geological Survey Bulletin 1350, 848 p. E. Luttrell, G.W., Hubert, M.L., Wright, W.B., Jussen, V.M., and Swanson, R.W., 1981, Lexicon of geologic names of the United States for 1968-1975: U.S. Geological Survey Bulletin 1520, 342 p. F. Luttrell, G.W., Hubert, M.L., and Jussen, V.M., 1986, Lexicon of new formal geologic names of the United States 1976-1980: U.S. Geological Survey Bulletin 1564, 191 p. G. Luttrell, G.W., Hubert, M.L., and Murdock, C.R., 1991, Lexicon of new formal geologic names of the United States 1981-1985: U.S. Geological Survey Bulletin 1565, 376 p. NA No publication available for names defined after 1985. Descriptions can be found in GNULEX. 28 FIELD 9 [7]. UNIQUE IDENTIFIER. A unique identifier consisting of a four-letter mnemonic plus a two-digit number is assigned to each record. It is used for recalling records for updating and for sorting. The mnemonic is derived from the geographic part of the name using a method devised by the AAPG Committee on Standard Stratigraphic Coding. English articles and prepo- sitions are deleted first; those in foreign languages are retained. The first letter of each remaining word is retained. Names beginning with Mc, O', De, or Van are treated as two words. Letters are then deleted, from right to left, in the following order until four remain: a, e, i, o, u, w, h, y, one of each double, t, n, s, r, l, d, c, m, f, g, p, k, b, v, x, j, q, z. All the records for each name have the same mnemonic but different numbers. 29