Identification_Information: Citation: Citation_Information: Originator: Calvin Crowell Daetwyler, Jr. Publication_Date: 1965 Title: Marine geology of Tomales Bay, Central California Geospatial_Data_Presentation_Form: Paper Publication_Information: Publication_Place: San Diego, CA Publisher: University of California, San Diego Other_Citation_Details: Funding from an American Chemical Society Donation Grant and National Science Foundation Grant 2550 Description: Abstract: "Tomales Bay is a submerged rift valley lying along the axis of the northwest-trending, seismically active San Andreas fault zone. Protected bay sediments are being deposited in a narrow, elongated, structural depression, characterized by known strike-slip faulting in historic times. The primary objective of this investigation is to determine the relative effects of normal depositional processes and contemporaneous strike-slip faulting on the Recent sediment facies, thickness, distribution, and depositional history in Tomales Bay. The stratigraphic succession and major internal structure of the Recent sediments in the southern two-thirds of the bay were determined by combining an acoustic-reflection survey (Sonoprobe) with lithologic data obtained from cores and test borings. Lithologic variations of the Tomales Bay surface sediments are attributed to 1.) the location and character of the sediment sources and 2.) the dispersal of sediment by tidal currents. Sandy sediments, supplied to the bay entrance by southerly longshore currents, have been subsequently redistributed throughout the northern third of the bay by tidal currents. Within this area of sand deposition, further textural subdivisions can be made on the basis of size-sorting relationships and size-frequency distributions. A textural transition zone marks the boundary between the sandy sediments and the fine-grained homogeneous sediments of the remaining two-thirds of the bay. Large quantities of sediment fill have been deposited in historic times and are situated near the mouths of Walker and Lagunitas Creeks, which have supplied the fine-grained sediment to the bay. The subaerial rift valley, prior to the Late Wisconsin rise in sea level, contained features of fault morphology. A prominent, discontinuous, center rift ridge was present throughout the valley. When developed this ridge divided the valley into two topographically lower segments elongated parallel to the axis of the San Andreas fault zone. During the initial post-Wisconsin transgression, a basal transgressive facies was deposited locally over the pre-transgressive surface. Sand was transported southward from Bodega Bay and a constricting sand spit was formed southeast of Hog Island. South of this spit, muds were deposited and a mudflat and channel system developed. As sea level continued to rise, the entrance to Tomales Bay was gradually filled by sand. A new bay mouth spit (Sand Point) began to form. The formation of this feature at the bay entrance decreased the sand supplied to the southern bay. The southernmost sand spit was gradually transgressed and younger muds began to fill in the former tidal channels and cover the older mudflats. Small depressions, found along the bay margins south of Pelican Point, are the relicts of former tidal channels and are not related to seismic activity. Locations of several fault traces are inferred from vertical separations of the pre-transgressive surface. Net slip of the fault displacements was not determined since clear lines of displacement were not established. Factors of basin geometry, a rising sea level, and the rates of sediment supply and dispersal, have been more important than active strike-slip faulting in determining the stratigraphy and internal structure of the Tomales Bay Recent sediments." Purpose: "The primary objective of this investigation is to determine the effects of recurrent contemporaneous strike-slip faulting and normal depositional processes on the Recent sediment facies, thickness, distribution and depositional history in Tomales Bay. Specific objectives are: 1.) to explain the distribution and internal structure of the Recent sediments in terms of their immediate source, and the dominant processes controlling their dispersal and deposition, and 2.) to evaluate the effects of faulting on the Recent sediments being deposited in this seismically active structural setting." Supplemental_Information: Data digitized by the USGS for inclusion into usSEABED. (http://walrus.wr.usgs.gov/usseabed) Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1965 Currentness_Reference: Publication date Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -122.9774 East_Bounding_Coordinate: -122.8529 North_Bounding_Coordinate: 38.2310 South_Bounding_Coordinate: 38.1051 Keywords: Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: University of California San Diego Theme_Keyword: Snapper grabs Theme_Keyword: Gravity cores 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 Structures Theme_Keyword: Sedimentary Textures Theme_Keyword: Terrigenous Sediments Place: Place_Keyword_Thesaurus: Geographic Names Information System (GNIS) Place_Keyword: Tomales Bay Place_Keyword: California, State of Access_Constraints: Thesis available at the USGS library and other libraries Use_Constraints: Cite Calvin C. Daetwyler Jr. and the University of California San Diego as the originators of the data. Point_of_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Scripps Institute of Oceanography, University of California San Diego Contact_Address: Address_Type: Physical Address: 9500 Gilman Drive City: La Jolla State_or_Province: CA Postal_Code: 92093 0223 Contact_Voice_Telephone: 858 534 3624 Browse_Graphic: Browse_Graphic_File_Name: Daetwyler_PhD_1965 Browse_Graphic_File_Description: Screen grab of GIS-produced sample distribution, with bathymetry and land for reference. Browse_Graphic_File_Type: JPG Data_Set_Credit: C. Daetwyler Jr. for collection and analysis of data. For inclusion into usSEABED, digitization: Jennifer Mendonca (USGS); Formatting corrections: Jane Reid (USGS) and Chris Jenkins (University of Colorado) Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: No estimate made for the accuracy of the data in the original report. Data digitized by the USGS and partners were visually compared to the source data, and corrected. Where appropriate, data were tested for completeness using MS Excel. Locations checked using GIS. Logical_Consistency_Report: Data fall within normal ranges for sediment percents, statistics, and other sediment parameters. Completeness_Report: For inclusion into usSEABED, appendix I (location of samples), Appendix II (grain size data), Appendix III (lithologic description of cores) and Appendix IV (Sound speed, density, porosity, and grain-size data, core 49 and 50) were completely digitized. Appendix V (Lithologic description of Merle Lawson water well No. 2 and Tomales Bay test borings) was not digitized. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Navigational technique not noted in report. Locations given to one-half seconds (degree, minute, second). Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: Water depths not noted in report. Lineage: Process_Step: Process_Description: Split samples were treated with 10 per cent hydrogen peroxide to remove organic matter, dispersed in the presence of Ca2+ ions by 0.005 molal sodium oxalate and 0.062 molal sodium carbonate. Wet sieved on a 0.062 mm sieve. When necessary, the size fraction larger than 2.0 mm was also separated by wet sieving. A standard pipette analysis was made of the fine fractions. The sand fraction was reduced to a subsample of a few grams with an Otto microsplit. The size distribution was determined by a continuous-recording sedimentation balance developed at SIO (van Andel, 1964). For inclusion into usSEABED, gravel values > 0 for 14 grab samples were integrated and sand/silt/clay values recalculated. Mean and median grainsize values and standard deviations (sorting) for those samples are not used. Source_Used_Citation_Abbreviation: Van Andel, 1964 Process_Date: Unknown Source_Produced_Citation_Abbreviation: Daetwyler_PhD_1965 Process_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Scripps Institute of Oceanography, University of California San Diego Contact_Address: Address_Type: Physical Address: 9500 Gilman Dr City: La Jolla State_or_Province: CA Postal_Code: 92093 0223 Contact_Voice_Telephone: 858 534 3624 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Vector Point_and_Vector_Object_Information: SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Point Point_and_Vector_Object_Count: 124 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Geographic: Latitude_Resolution: 0.00014 Longitude_Resolution: 0.00014 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: Gravel Attribute_Definition: Gravel Attribute_Definition_Source: Wentworth 1932 Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0 Range_Domain_Maximum: 29.9 Attribute_Units_of_Measure: Percent Attribute_Measurement_Resolution: 0.1 Attribute: Attribute_Label: Sand Attribute_Definition: Sand Attribute_Definition_Source: Wentworth 1932 Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.2 Range_Domain_Maximum: 100 Attribute_Units_of_Measure: Percent Attribute_Measurement_Resolution: 0.1 Attribute: Attribute_Label: Silt Attribute_Definition: Silt Attribute_Definition_Source: Wentworth 1932 Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.5 Range_Domain_Maximum: 68.4 Attribute_Units_of_Measure: Percent Attribute_Measurement_Resolution: 0.1 Attribute: Attribute_Label: Clay Attribute_Definition: Clay Attribute_Definition_Source: Wentworth 1932 Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 1.3 Range_Domain_Maximum: 75.3 Attribute_Units_of_Measure: Percent Attribute_Measurement_Resolution: 0.1 Attribute: Attribute_Label: Mud Attribute_Definition: Mud Attribute_Definition_Source: Wentworth 1932 Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0 Range_Domain_Maximum: 11.8 Attribute_Units_of_Measure: Percent Attribute_Measurement_Resolution: 0.1 Attribute: Attribute_Label: Mean Attribute_Definition: Mean of grainsize distributions Attribute_Definition_Source: Inman, 1952 Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 1.6 Range_Domain_Maximum: 7.28 Attribute_Units_of_Measure: Phi Attribute_Measurement_Resolution: 0.01 Attribute: Attribute_Label: Dev. Attribute_Definition: Standard deviation of grainsize distribution (sorting) Attribute_Definition_Source: Inman, 1952 Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.24 Range_Domain_Maximum: 1.91 Attribute_Units_of_Measure: Phi Attribute_Measurement_Resolution: 0.01 Attribute: Attribute_Label: Median Attribute_Definition: Median grainsize Attribute_Definition_Source: Inman, 1952 Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 1.58 Range_Domain_Maximum: 8.95 Attribute_Units_of_Measure: Phi Attribute_Measurement_Resolution: 0.01 Attribute: Attribute_Label: Porosity Attribute_Definition: Porosity of sample Attribute_Definition_Source: Source report Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 63.7 Range_Domain_Maximum: 76. Attribute_Units_of_Measure: Phi Attribute_Measurement_Resolution: 0.1 Attribute: Attribute_Label: Bulk density Attribute_Definition: Wet bulk density Attribute_Definition_Source: Source report Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 1.41 Range_Domain_Maximum: 1.62 Attribute_Units_of_Measure: Gm/cc Attribute_Measurement_Resolution: 0.01 Attribute: Attribute_Label: Text Attribute_Definition: Descriptive text Attribute_Definition_Source: Source report Attribute_Domain_Values: Unrepresentable_Domain: Descriptive text including color and Munsell code Attribute: Attribute_Label: Shepard class Attribute_Definition: Location of sample on the sand-silt-clay ternary Attribute_Definition_Source: Shepard 1954 Attribute_Domain_Values: Unrepresentable_Domain: Textural name representing position on sand-silt-clay ternary. Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: Scripps Institute of Oceanography, University of California San Diego Contact_Address: Address_Type: Physical Address: 9500 Gilman Drive City: La Jolla State_or_Province: CA Postal_Code: 92093 0223 Contact_Voice_Telephone: 858 534 3624 Resource_Description: C.C. Daetwyler, Jr's PhD thesis, 1965 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 Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: Mail and physical Address: 345 Middlefield Road City: Menlo Park State_or_Province: CA Postal_Code: 94025 Contact_Voice_Telephone: 650.329.5026 Contact_Electronic_Mail_Address: men_lib@usgs.gov Resource_Description: Daetwyler PhD 1965 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 the limitations of the data due to possible imprecision due to navigational inaccuracies, statistical limitations, and digitizing errors. Standard_Order_Process: Non-digital_Form: Report is available for viewing or checkout at the USGS library, Menlo Park, and at other libraries. Fees: None Technical_Prerequisites: None Available_Time_Period: Time_Period_Information: Single_Date/Time: Calendar_Date: 1965 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.