Geologic map of the Fawnskin 7.5' quadrangle, San Bernardino County, California

This data set maps and describes the geology of the Fawnskin 7.5' quadrangle, San Bernardino County, California and contains original U.S. Geological Survey data generated by detailed field observation and by interpretation of aerial photographs. The geologic map covers part of the northern San Bernardino Mountains. Bedrock units in the San Bernardino Mountains are dominated by large Cretaceous and Jurassic granitic bodies ranging in composition from monzogranite to gabbro, and include lesser Triassic monzonite. These granitic rocks intrude highly faulted and folded Late Proterozoic and Paleozoic formations representative of those found in the southern Great Basin. Low-angle thrust faults, many of them complexly folded, cut the Late Proterozoic and Paleozoic formations. A large, deformed cataclastic zone in the western part of the quadrangle cuts pre-Late Cretaceous units, and is intruded by Late Cretaceous plutons. Spanning the Pleistocene in age, large alluvial fans flank the north side of the mountains, and are dominated by debris flow deposits. Young, south dipping reverse faults, some with moderately to well eroded fault scarps, discontinuously flank the northern edge of the mountains. Young and old high-angle faults are mapped within the range. Created using Environmental Systems Research Institute's ARC/INFO software, the database consists of the following items: (1) a map coverage containing faults, geologic contacts and units, (2) a coverage showing structural point data, (3) a coverage containing linear structural data, (4) a coverage showing geologic line ornamentation and (5) six additional INFO data tables (.rel) that contain detailed, coded, geologic information such as texture, fabric, color, and mineralogy,. These additional data are accessible to the user through the utilization of ARC/INFO relate environments and provide the user access to as much or as little of the encoded data as required. In addition, the data set includes the following graphic and text products: (1) A PostScript graphic plot-file containing the geologic map, topography, cultural data, a Correlation of Map Units (CMU) diagram, a Description of Map Units (DMU), and a key for point and line symbols; (2) PDF files of this Readme (including the metadata file as an appendix), Description of Map Units (DMU), and a screen graphic of the plot produced by the PostScript plot file. The geologic map database contains original U.S. Geological Survey data generated by detailed field observation and by interpretation of aerial photographs. Within the database, geologic contacts are represented as lines (arcs), geologic units as polygons, and site-specific data as points. Polygon, arc, and point attribute tables (.pat, .aat, and .pat, respectively) uniquely identify each geologic datum. Version 1.1 of this digital release differs from Version 1.0 mainly by changes and additions to conform to the more recently released digital geologic map of the Butler Peak quadrangle (OF 00-145), which adjoins the Fawnskin quadrangle on the west. Along the western edge of the quadrangle several polygons of Quaternary units are added and the names of several are changed. Colors of some granitic units are changed to conform to colors assigned to the same units in the Butler Peak quadrangle.本数据集针对加利福尼亚州圣贝纳迪诺县的福恩斯金（Fawnskin）7.5分四边形地图幅开展地质填图与描述，包含由美国地质调查局（United States Geological Survey, USGS）通过详细野外观测与航空照片解译生成的原始数据。该地质图幅覆盖圣贝纳迪诺山脉北部部分区域。 圣贝纳迪诺山脉的基岩单元以大型白垩纪和侏罗纪花岗质岩体为主，岩石成分从二长花岗岩到辉长岩不等，同时包含少量三叠纪二长岩。这些花岗质岩体侵入了强烈断裂褶皱的晚元古代和古生代地层，这类地层与大盆地南部出露的典型地层特征一致。低角度逆冲断层（多数具复杂褶皱构造）切割了晚元古代和古生代地层。测区西部存在一条大型变形碎裂岩带，其切割了晚白垩世之前的地层，并被晚白垩世深成岩体侵入。 分布于山脉北翼的大型冲积扇时代贯穿更新世，其主体为碎屑流沉积。年轻的南倾逆断层（部分具有中等至强烈侵蚀的断层崖）断续分布于山脉北缘。测区内部还填绘了不同活动期次的高角度断层。 本数据库由环境系统研究所（Environmental Systems Research Institute, ESRI）的ARC/INFO软件构建，包含以下内容：(1) 包含断层、地质接触界线与地质单元的地图覆盖层；(2) 展示构造点数据的覆盖层；(3) 包含线性构造数据的覆盖层；(4) 展示地质线条饰纹的覆盖层；(5) 6个额外的INFO数据表格（.rel格式），其中存储了纹理、组构、颜色、矿物学等详细编码地质信息。用户可通过ARC/INFO关联环境调用这些附加数据，按需获取全部或部分编码信息。 本数据集还包含以下图形与文本成果：(1) 一份PostScript格式的图形绘图文件，其中包含地质图、地形图、人文地理数据、图幅单元对比图（Correlation of Map Units, CMU）、图幅单元描述（Description of Map Units, DMU）以及点、线符号图例；(2) 本说明文档（含附录元数据文件）、图幅单元描述（DMU）以及PostScript绘图文件生成的屏幕截图的PDF文件。 本地质图数据库同样包含由美国地质调查局通过详细野外观测与航空照片解译生成的原始数据。在数据库中，地质接触界线以线（弧段）表示，地质单元以多边形表示，点属性数据以点要素表示。多边形、弧段与点属性表（分别为.pat、.aat与.pat）可唯一标识每一处地质数据点位。 本次数字发布的1.1版本与1.0版本的主要差异在于，为适配近期发布的毗邻该测区西翼的巴特勒峰（Butler Peak）四边形地图幅（OF 00-145）数字地质图而进行了修改与增补。在测区西缘，新增了若干第四纪单元多边形，并修改了部分单元名称；部分花岗质单元的颜色被调整，以匹配巴特勒峰地图幅中对应单元的配色。