Geology and surrounding recent marine sediments of Anacapa Island

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: David W. Scholl

Publication_Date: 1959

Title:

Geology and surrounding recent marine sediments of Anacapa Island

Geospatial_Data_Presentation_Form: Paper

Publication_Information:

Publication_Place: Los Angeles, CA

Publisher: University of Southern California

Other_Citation_Details:

Ship, office, and laboratory facilities support from the Allan Hancock Foundation.

Description:

Abstract:

"Anacapa Island lies nearly twelve miles off the southern California coast along latitude 34 00'30"N. It is the easternmost member of the four Santa Barbara Islands and is also the closest to shore of the eight California channel islands. The island is approximately five miles in length but is only 1.05 square miles in area. Two gaps divide the island into smaller eastern, central, and western islands. The western island has a summit elevation of 930 feet, and it is the highest and largest of the three. Drainage is principally to the north by intermittent resequent streams. Prominent wave-cut terraces are present at elevations of about 600 and 250 feet. The higher terrace is present only on the western island, but the lower terrace occurs on each of the islands and forms a summit platform atop the central and eastern islands. The insular Anacapa shelf includes about thirty-six square miles of the surrounding shallow submerged sea floor. North of the island the shelf is approximately three miles wide, but the southern shelf is less than half this width. To the west, the shelf area extends beneath Acapaca Passage and merges with the shelf of neighboring Santa Cruz Island. The shelf area east of the island is poorly defined. Declivities of the northern and the southern shelves average about 1 degree 40' out to a depth of about 270 feet. The outer edge of the southern shelf usually occurs at this depth, but north of the island a two-mile wide terrace with an overall gradient of 0 degrees 5' extends to near the shelf edge, which occurs at an average depth of 300 feet. Other flattenings of the shelf are present at depths of 60, 100, 180, and 330 feet. The submarine terraces are thought to be wave-cut features of Wisconsin age. Lower Middle Miocene andesitic lavas and pyroclastic rocks of the Conejo formation form the bulk of Anacapa Island. Approximately 1700 feet of this formation is exposed on the south side of the western island. Near the base of the volcanic series are two interbeds of San Onofre breccia, which are separated from each other by 100 to 150 feet of eruptive rocks. This formation crops out on the western and central islands; each unit of the formation has a maximum thickness of thirty five or forty feet. Fossiliferous Lower Pleistocene terrace deposits overlie the San Onofre breccia on the central island. The marine deposits are overlain in turn by Upper Pleistocene and Recent nonmarine terrace sands. The geology of the submerged insular shelf is similar to the island proper except for outcrops of the Monterey formation beneath Anacapa Passage. Most submarine outcrops occur on the shelf areas east and west of the island, where a thin veneer of Recent and relict Pleistocene sediments is present. A paucity of rock bottom north of the island indicates a thick cover of Recent sediment. Anacapa is essentially a gentle north-dipping (2-20 degree) sequence of volcanic rocks, and it is structurally related to the other Santa Barbara Islands and to the Santa Monica Mountains. The islands and the Santa Monica Mountains form the structural province of Anacapia and also the western portion of the Transverse Range Physiographic Province. Unconsolidated sediments overlying the insular shelf are characterized by an average median diameter of 0.360 mm, a sorting coefficient of 1.73, a carbonate content of 45.5 percent, and a 0.7 percent organic matter content. Calcium carbonate and organic matter increase with distance from the island. Median diameters decrease with increasing depth north and south of the island, but increase with distance to the east and west. Detrital sediments or deposits which have carbonate contents less than fifty percent occur principally north and south of the island. They are coarsest to the south because grains smaller than about 0.125 mm tend to bypass the narrow and rather steeply sloping southern shelf. Calcareous sediment types are characteristic of the eastern and western shelf areas where an environment of nondetrital sedimentation prevails. Most of the calcareous matter is composed of mollusk fragments, Lithothamnium debris, bryozoan zoaria, and echinoid spines and plates. Foraminifera also contribute, but they are most abundant in the sediments near the outer edges of the northern and southern shelves.

Purpose:

"Until this study, Anacapa Island, one of the smallest of [the eight islands off the southern California coast] had never been mapped geologically and little was known of its shelf sediments."

Supplemental_Information:

Samples collected aboard the R/V Velero IV; Data digitized by the USGS for inclusion into usSEABED (<http://walrus.wr.usgs.gov/usseabed>)

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 1957

Ending_Date: 1958

Currentness_Reference: Publication date

Status:

Progress: Complete

Maintenance_and_Update_Frequency: None planned

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -119.4944

East_Bounding_Coordinate: -119.2617

North_Bounding_Coordinate: 34.0764

South_Bounding_Coordinate: 33.9647

Keywords:

Theme:

Theme_Keyword_Thesaurus: None

Theme_Keyword: University of Southern California

Theme_Keyword: Allan Hancock Foundation

Theme_Keyword: Orange peel grab

Theme:

Theme_Keyword_Thesaurus: ISO 19115 Topic Category

Theme_Keyword: Oceans and Estuaries

Theme_Keyword: Location

Theme_Keyword: GeoscientificInformation

Theme:

Theme_Keyword_Thesaurus:

NASA/Global Change Master Directory (GCMD) Earth Science Keyword. Version 5.3.3

Theme_Keyword: Marine Sediments

Theme_Keyword: Sediment Composition

Theme_Keyword: Sedimentary Textures

Theme_Keyword: Terrigenous Sediments

Place:

Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)

Place_Keyword: California

Place_Keyword: Anacapa Island

Place_Keyword: Anacapa Passage

Place_Keyword: Channel Islands

Place:

Place_Keyword_Thesaurus: None

Place_Keyword: Continental

Place_Keyword: Borderland

Access_Constraints:

None. Thesis is available at the USGS Library and some libraries.

Use_Constraints:

Cite David W. Scholl and the University of Southern California as originators of the data.

Point_of_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: David W. Scholl

Contact_Organization: Now at the U.S. Geological Survey (emeritus)

Contact_Address:

Address_Type: Physical and Mail

Address: 345 Middlefield Road, MS 999

City: Menlo Park

State_or_Province: CA

Postal_Code: 94025

Contact_Voice_Telephone: 650-329-4762

Contact_Electronic_Mail_Address: dscholl@usgs.gov

Browse_Graphic:

Browse_Graphic_File_Name: Scholl_MS_59

Browse_Graphic_File_Description:

Sample distribution with coastline and bathymetry for reference.

Browse_Graphic_File_Type: .jpg

Data_Set_Credit:

David W. Scholl at University of Southern California for the collection and analysis of data. For inclusion into usSEABED: digitization: Adam Jackson (USGS); Formatting corrections: Jane Reid (USGS) and Chris Jenkins (University of Colorado).

Native_Data_Set_Environment:

Tkme: Another editor for formal metadata by Peter N. Schweitzer (U.S. Geological Survey, Reston, VA 22092), version 2.9.13, Microsoft Windows Version 5.1; Microsoft Word 2000 9.0

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

Locations, descriptions, statistical data were digitized by hand (typed in), visually compared to source and corrected as needed. Where appropriate, data were tested for completeness using MS Excel.

Logical_Consistency_Report: Data fall within normal ranges for analytical results.

Completeness_Report:

No assessment made for original report. For usSEABED, appendices 1 and 2 were completely digitized. Some information from the report text may also be included in usSEABED.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

Navigational techniques not noted in the report. Locations given to degrees, minutes, seconds.

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report:

Depth determination techniques not noted in the report. Water depths not given.

Lineage:

Process_Step:

Process_Description:

"Textural parameters of sandy sediments were determined with the Emery Settling Tube (Emery, 1938). Finer-grained sediments were analyzed by the pipette method (Krumbein and Pettijohn, 1938). ... Gravels were further divided into grade sizes with additional screening. Carbonate content was measure by leaching a known weight of sediment with dilute hydrochloric acid. Any weight loss after treatment and filtration was calculated as precent calcium carbonate. ... Organic carbon was determined by the potassium dichromate reduction technique described by Allison (1935). Organic carbon percentages were multiplied by a factor of 1.7 to convert to total organic matter (Emery and Rittenberg, 1952)".

Source_Used_Citation_Abbreviation: Allison, 1935

Source_Used_Citation_Abbreviation: Emery, 1938

Source_Used_Citation_Abbreviation: Emery and Rittenberg, 1952

Source_Used_Citation_Abbreviation: Krumbein and Pettijohn, 1941

Process_Date: Unknown

Source_Produced_Citation_Abbreviation: Scholl_MS_59

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: David W. Scholl

Contact_Organization: Now at the U.S. Geological Survey (emeritus)

Contact_Address:

Address_Type: Physical and Mail

Address: 345 Middlefield Road, MS 999

City: Menlo Park

State_or_Province: CA

Postal_Code: 94025

Contact_Voice_Telephone: 650-329-4762

Contact_Electronic_Mail_Address: dscholl@usgs.gov

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Vector

Point_and_Vector_Object_Information:

SDTS_Terms_Description:

SDTS_Point_and_Vector_Object_Type: Entity point

Point_and_Vector_Object_Count: 98

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Geographic:

Latitude_Resolution: 0.00028

Longitude_Resolution: 0.00028

Geographic_Coordinate_Units: decimal degrees

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: Point

Entity_Type_Definition: SDTS point

Entity_Type_Definition_Source: Source report

Attribute:

Attribute_Label: AHF Sta. #

Attribute_Definition: Station number

Attribute_Definition_Source: Allan Hancock Foundation

Attribute_Domain_Values:

Unrepresentable_Domain: Sequential alpha numeric code

Attribute:

Attribute_Label: Median

Attribute_Definition: Median grainsize distribution

Attribute_Definition_Source: Source report

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: -2.0

Range_Domain_Maximum: 4.8

Attribute_Units_of_Measure: Phi

Attribute_Measurement_Resolution: 0.1

Attribute:

Attribute_Label: CaCO3

Attribute_Definition: CaCO3 in sample

Attribute_Definition_Source: Allison, 1935

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 5.1

Range_Domain_Maximum: 93.9

Attribute_Units_of_Measure: Percent

Attribute_Measurement_Resolution: 0.1

Attribute:

Attribute_Label: Organic matter

Attribute_Definition: Organic matter

Attribute_Definition_Source: Allison, 1935

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 0.27

Range_Domain_Maximum: 3.98

Attribute_Units_of_Measure: Percent

Attribute_Measurement_Resolution: 0.01

Attribute:

Attribute_Label: Lithologic descriptions

Attribute_Definition: Lithologic descriptions of rock samples

Attribute_Definition_Source: Source report

Attribute_Domain_Values:

Unrepresentable_Domain: Written descriptions

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: University of Southern California

Contact_Address:

Address_Type: Physical

Address: Zumberge Hall

Address: 3651 Trousdale Parkway

City: Los Angeles

State_or_Province: CA

Postal_Code: 90089

Contact_Voice_Telephone: 213-740-6106

Resource_Description: D. Scholl MS thesis 1959

Distribution_Liability:

Although this dataset has been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data. Users of the data should be aware of limitations of the data due to possible imprecision due to navigational inaccuracies and limitations of the statistical data.

Standard_Order_Process:

Non-digital_Form: Report is available at some libraries.

Fees: None

Technical_Prerequisites: None

Available_Time_Period:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 1959

Metadata_Reference_Information:

Metadata_Date: 2005

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: U.S. Geological Survey

Contact_Person: Jane A. Reid

Contact_Position: Geologist

Contact_Address:

Address_Type: Physical and mail

Address: 400 Natural Bridges Drive

City: Santa Cruz

State_or_Province: CA

Postal_Code: 95060

Contact_Voice_Telephone: 831-427-4727

Contact_Electronic_Mail_Address: jareid@usgs.gov

Contact_Instructions: email preferred

Metadata_Standard_Name: CSDGM Version 2

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Access_Constraints: None

Metadata_Use_Constraints:

Metadata was written by a user of the data. Any information contained in the physical report is authoritative and supercedes any information given here.