Explanation of database files for Preliminary geomorphic map of the Kitsap Peninsula, Washington USGS Open-File Report 2009-1033, version 1.0 Database by Ralph A. Haugerud INTRODUCTION ============ This map, interpreted from a 6-ft lidar DEM by the author (see DATA PROVENANCE, below), describes the distribution of geomorphic units, e.g., glaciated fluted surface, hillslope, alluvial flat, and beach face, not the distribution of earth materials as in a geologic map. The area covered by the map is the Kitsap Peninsula of Washington State, including Bainbridge Island and Blake Island. The mapped area includes all of Kitsap County and part of Mason County. FILES IN DATABASE PACKAGES ========================== The following files are in the coverage database package: kitsapg.e00 ArcInfo export file for coverage kitsapg, the geologic map-content of this report. Contains lines with attribute LTYPE and polygons with attribute UNIT. Values and value-definitions for these attributes are given below. Not all lines connect at both end-points to form polygons: in ArcInfo terminology, some lines dangle. Projection is Washington State Plane North, datum NAD83, units FEET kitsapc.e00 ArcInfo export file for coverage kitsapc, the CORRELATION OF MAP UNITS diagram. Contains polygons with attribute UNIT, lines, and annotation. Cartographic projection, units INCHES kitsapanno.e00 ArcInfo export file for coverage kitsapanno, the annotation for the map. Contains annotation classes UNIT, WATER, PLACES, and TOWNS. Projection and datum match kitsapg.e00 kitsap_metadata.txt FGDC-compliant metadata for coverage kitsapg, in text format kitsap_text.pdf PDF file of the map text, including sections INTRODUCTION, METHODS, LANDSCAPE EVOLUTION, REFERENCES CITED, DESCRIPTION OF MAP UNITS, and Figure 1, formatted for 8.5 inch by 11 inch pages plotting_resources.zip Base-map data (township, section, and range boundaries, streams, graticule, and 10-meter contours), code, and symbols needed to plot the map. This material will probably only be useful to ArcInfo users. It is provided as a convenience to those adventurous GIS experts who wish to re-create the map graphic. No support is available and documentation is minimal. README.txt This file The following files are in the shapefile database package: kitsapgl.dbf Shapefiles that describe lines with attribute LTYPE kitsapgl.shp ----ditto---- kitsapgl.sfx ----ditto---- kitsapgl.shp.xml ----ditto---- kitsapgp.dbf Shapefiles that describe polygons with attribute UNIT kitsapgp.shp ----ditto---- kitsapgp.shx ----ditto---- kitsapgp.shp.xml ----ditto---- Shapefiles kitsapgl and kitsapgp together are equivalent to coverage kitsapg in the coverage database package. Annotation is not easily encoded in the shapefile format, thus shapefile equivalents to kitsapc.e00 and kitsapanno.e00 are not supplied. Shapefile data are in Washington State Plane North projection (zone 5601), datum NAD83, units feet. kitsap_metadata.txt FGDC-compliant metadata for coverage kitsapg, in text format kitsap_text.pdf PDF file of the map text, including sections INTRODUCTION, METHODS, LANDSCAPE EVOLUTION, REFERENCES CITED, DESCRIPTION OF MAP UNITS, and Figure 1, formatted for 8.5 inch by 11 inch pages README.txt This file DOMAINS AND DEFINITIONS FOR KEY ATTRIBUTES ========================================== Values and value-definitions for attribute LTYPE, table kitsapg.aat ------------------------------------------------------------------- contact: Boundary between two surface units. In many places one alluvial flat is incised into another belonging to the same map unit. Where the separations are sufficiently distinct, contacts are mapped within these map units fault: Aligned minor scarps and gullies formed by surface rupture, commonly somewhat degraded by subsequent scarp collapse fossil shoreline: Morphologic discontinuity inferred to mark former marine or lacustrine shoreline scratch boundary: Poorly-defined boundary between two surface units shoreline: Morphologic break at uphill edge of modern marine beach, commonly at base of shoreline bluff (shoreline angle of many authors) waterline: Edge of water body at time lidar data were acquired. Lateral position and elevation vary with tide stage Values and value-definitions for attribute UNIT, table kitsapg.pat ------------------------------------------------------------------ af: Alluvial fan--Moderately sloping (mostly 2-5 degrees) surface, mostly conic, at drainage confluences and along toes of valley walls. Slope suggests sediment transport is dominated by debris flow or infrequent floods al: Alluvial flat--Stream-shaped surface, either depositional or strath. Could be latest Pleistocene or Holocene in age. Locally (for example, west of Harper) includes nearshore flat formed by wave action bf: Beach face--Steeper upper beach, commonly above mean low-water elevation. At upper edge, bounded by berm crest or toe of bluff blank: Void in lidar DEM bs: Backshore area--Flat built by modern beach accretion. Elevation near mean high water. Commonly has distinct berm crest at seaward edge. Locally, mapped as: ch: Channel--Smooth-walled channels, apparently water-carved, but without apparent source or sink for flowing water. As mapped, includes both near-horizontal floors and steeper walls. Most have smooth transitions between floor and wall. Lack of floor-wall slope break suggests that channels were entirely filled with flowing water, not carved by water flowing across floor and subsequent collapse of valley sidewalls. Lack of obvious source or sink suggests presence of surrounding ice when channels formed df: Delta face--Smooth moderate-slope surfaces at and below opening of alluvial flats onto lower elevation areas. Larger delta fronts and associated delta tops are common sites for quarries (mapped as modified land, unit m) df?: Delta face (queried)--Smooth moderate-slope surfaces at and below opening of alluvial flats onto lower elevation areas. Larger delta fronts and associated delta tops are common sites for quarries (mapped as modified land, unit m). Queried where identity is less certain esker: Sinuous narrow ridge fill: Artificial fill--Surface of fill bodies beneath highways and railways, mapped because of possibility of failure during severe seismic shaking g: Glaciated surface--Ground modified by flowing ice. Mostly subdivided into: gb: Glaciated bedrock surface--Ice-modified ground that has lumps or transverse ribs (eroded bedding) indicative of erosion from bedrock rather than from unconsolidated material gb?: Glaciated bedrock surface (queried)--Ice-modified ground that has lumps or transverse ribs (eroded bedding) indicative of erosion from bedrock rather than from unconsolidated material. Queried where identity is less certain gf: Fluted glaciated surface--Characterized by well-organized flutes that have elongation ratios (length/width) typically greater than 10. Flutes are typically hundreds of meters wide, heights are 10 to 30 m. Locally, mapped as: gfc: Rippled fluted glaciated surface--Fluted glacial surface that has transverse ripples or “chatter marks.” Wavelengths of transverse ripples are 40 to 100 m. Ripple height can be as great as a few meters; perhaps ripples originated as crevasse fillings gp: Pockmarked glaciated surface--Weakly fluted ground that has irregular pits and lumps. In many places, appears to be gradational between rippled glaciated surfaces and kame-kettle topography gs: Scalloped glaciated surface--Characterized by well-developed swales that cross fluted surface and form nearly equant hills that have diameters of about 1 km and heights of 10 to 40 m. Most hills are mantled with typical flutes. Locally, mapped as: gsc: Rippled scalloped glaciated surface--Scalloped glaciated surface that has transverse ripples gtw: Glacial trough wall--Steep, ice-molded surface; commonly has distinct slope break at up-slope margin; commonly is transverse to general direction of ice flow; commonly grades to lumpy ice-disintegration terrane at base of slope h: Hillslope--Steep (commonly 20-35 degrees) surface that appears to be dominated by colluviation, debris-flow, shallow-landslide, and other mass-movement processes. Mostly with distinct breaks in slope at upslope and downslope margins. Cut into adjacent topography. As mapped, includes narrow alluvial flat on floors of minor gullies. Lack of significant rounding at tops and toes of hillslope suggests that, in this terrain and in limited age of these slopes, diffusive processes have not been significant. For clarity, most small areas of unit are unlabelled. Locally, mapped as: h0: Older hillslope--Lower gradient slope located uphill of hillslope that have higher, more typical gradients. Position and lower gradient argue that older hillslope developed in a regime of lower slope stability, perhaps without vegetation cover hal: Holocene alluvial flat--Stream valley floor. Recognized by low slope, planarity, and position in topographic lows along active drainage paths kettle: Kettle--Closed depression that has moderately to steeply sloping sides; commonly embedded in outwash flat kk: Kame-kettle surface--Irregular ground characterized by steep-walled closed depressions (kettles), collapse features, eskers, and common alluvial flats. Locally, mapped as: lag: Lagoon--Areas within backshore that commonly are flooded at high tide ls: Landslide--Surface of deep-seated landslide, recognized by uphill scarps, bulbous toes, position in hillslope hollows, and (locally) rumpled surface. Queried where identity as landslide is less certain. Some landslides, particularly those nestled in glaciated upland, may be inactive and stable in current conditions m: Modified land--Filled and (or) graded area. Generally not mapped except along major roads and where filling and grading is sufficiently extensive to preclude inference of precursor surface. Locally, mapped as: ob: Old beach--Fossil beach at supra-tidal elevations. Mapped at heads of Lynch Cove, North Bay, Burley Lagoon, in Manchester-Port Orchard area, and on southern Bainbridge Island. May include equivalents of modern backshore, beach face, and tide flat. In all locales, presence records coseismic uplift during one or more large earthquakes at about A.D. 900. Locally, mapped as: obb: Old beach berm--Low ridge along former shoreline ohal: Older alluvial flat--Mid-Holocene stream valley floor, uplifted and isolated by one or more large earthquakes at about 900 AD owb: Outwash flat of Bretz age--Alluvial flat graded to glacial Lake Bretz owb?: Outwash flat of Bretz age (queried)--Alluvial flat graded to glacial Lake Bretz. Queried where Bretz age is less certain owm: Outwash flat graded to marine limit--Alluvial flat graded to upper limit of latest Pleistocene marine waters owr: Outwash flat of Russell age--Alluvial flat graded to glacial Lake Russell. Russell-age alluvial flats in Union River and Burley Creek drainages, and perhaps elsewhere, formed as kame terraces confined between valley walls and now-absent ice. Locally (for example, west of Belfair, east of Burley) includes some surfaces carved by wave action along shore of glacial Lake Russell r: Rilled slope--Steep older, glaciated surface dissected by pervasive minor parallel gullies sl: Sublacustrine surface--Older surface, mostly glacial; smoothed by subaquatic slumping and lacustrine deposition. Mapped on basis of subdued topography and position sm: Submarine surface--Older surface, mostly glacial; smoothed by tidal and subtidal currents, marine deposition, and wave action. Mapped on basis of subdued topography and position below late Pleistocene marine limit tf: Tide flat--Low-slope lower beach. Commonly at elevations below mean lower low-water; higher at heads of inlets w: Wetland--Planar surface of low slope. Mapped on basis of geometry, position in topographic lows, and distinctive surface texture that probably reflects wetland vegetation. Identification as wetland corroborated by approximate correspondence with third-party wetland inventories (Kitsap County GIS, 2006) and limited field checking wtr: open water DATA PROVENANCE =============== This map was interpreted from 6-foot lidar DEMs provided by the Puget Sound Lidar Consortium, http://pugetsoundlidar.org. The lidar DEMs were derived from 1 pulse/m2 lidar surveys conducted in early 2000 and winter 2001-2002. From a DEM, I calculated four images: a northeast-illuminated gray hillshade; a northwest-illuminated gray hillshade; a color image in which hue corresponds to local slope; and a color image with hue calculated from elevation and darkness as a non-linear function of local slope, to make small variations of slope at low slopes visible at the expense of suppressing the visibility of similar variations at higher slopes. I found the latter to be the most useful. With these images as interchangeable backdrops, I digitized geomorphic unit boundaries on-screen in a GIS environment, interpreting on the fly. The ability to pan and zoom at will while working on-screen is most appreciated, but the limited spatial context is at times challenging. At intervals I made large-format plots of the in-progress map to establish context and thus resolve areas where an interpretation was not obvious, as well as to edit the emerging map for consistency. ACCURACY ======== The accuracy of the DEM-derived geomorphic map is limited in several ways. Most unit boundaries are located on slope breaks. Absent careful modeling, slope breaks can be located no more accurately than 2-3 DEM cells (12 to 18 ft). Boundaries not on slope breaks are less accurately located. For example, boundaries between varieties of glaciated surface were drawn at subtle changes in texture, thus all such contacts are shown as wash boundaries. Subsequent work may lead to substantial revision of these boundaries. Some lines were automatically smoothed after digitizing in order to minimize artifacts. Visualization scale provides another limit: my experience is that I do not place lines any more accurately than a few pixels at the visualization scale. On a 75 pixel-per-inch computer display, my usual working scale varied from 1:3,000 to 1:12,000. One's stratigraphic concepts further limit accuracy. Misconceived map units—for example, units that require subdivision of a spectrum of morphologies that result from a single process, or lumping of surfaces that result from distinct processes—may result in a map that is thematically wrong, or (more commonly) requires unit boundaries that cannot be located precisely. A particular challenge is posed by overprinted ground, such as glaciated ground modified by marine and (or) lacustrine processes. While this map is presented at a scale of 1:36,000, accuracy and completeness of much of the underlying digital map data should allow their use at scales as large as 1:12,000, that is, a nominal accuracy of +/- 30 feet. The quality of the lidar base limits interpretation in three settings: (1) In dense, unthinned second-growth forest, very few laser beams reached the ground and the topography is particularly ill-defined. (2) The despike algorithm is prone to misclassifying bluff edges as vegetation, leading to common scalping of edges. (3) Interpolation from scattered ground returns to a continuous surface tends to bridge across narrow ravines and shoreline angles; this bridging is particularly common where steep slopes meet open water and there are few returns from the water surface as specular reflection (instead of scattering) has directed incident laser light away from the lidar instrument. Such bridging results in local anomalies such as contours that cross water bodies. Wherever possible, I have attempted to map through defects in the base; that is, I mapped the interpreted landscape. Similarly, I have attempted to map the landscape as it was prior to human modification. Exceptions are major road corridors, mapped as modified land to help orient the map user visually, and the surfaces of highway fills, mapped because of their propensity to fail during severe seismic shaking. Mapping the pre-modification landscape was particularly challenging along the north side of southern Hood Canal, between Ayres Point and the Union River, where a roadway is superimposed on a possible uplifted mid-Holocene beach flat. TO OBTAIN DATA ==================== These data are available on the World Wide Web at http://pubs.usgs.gov/of/2009/1033. The database package and PDF plot-files for the two map sheets may also be obtained on CD by sending a request with return address to Karen Wheeler (or Ray Wells) US Geological Survey, MS 973 345 Middlefield Road Menlo Park, CA 94025 kwheeler@usgs.gov (or rwells@usgs.gov) Be sure that your request identifies this report, OF2009-1033. TO OBTAIN PAPER PLOTS ===================== From a commercial vendor: Download the plotfiles (2 files, Sheet1.pdf and Sheet2.pdf) or request them on CD (see above). Take the files to a commercial vendor with a large-format plotter (at least 36” wide). Make sure the vendor is capable of reading your digital media (CD, portable hard drive, USB drive, or otherwise) and plotting PDF files. From the U.S. Geological Survey: The U.S. Geological Survey provides a print on demand service for digital maps such as this report. To obtain plots, contact the U.S. Geological Survey: USGS Information Services Box 25286 Denver Federal Center Denver, CO 80225-0046 303-202-4200 888-ASK-USGS FAX: 303-202-USGS infoservices@usgs.gov Be sure that your request identifies this report, OF2009-1033. FOR FURTHER INFORMATION ======================= Contact Ralph Haugerud US Geological Survey c/o Dept Earth & Space Sciences Box 351310 University of Washington Seattle, WA 98195 rhaugerud@usgs.gov 206-713-7453