Surficial Clay Thickness Points

CLAY_ILITH_PTS_IN is a point shapefile that shows total thickness of clay, as derived from logs of water wells in the state of Indiana. (It presents the source data used to create a grid named "CLAY_ILITH_IN" in a shapefile format.) The data were obtained from the iLITH Database of the Indiana Geological Survey. The following explanation of the iLITH Database appears in Open-File Study 00-8 of the Indiana Geological Survey: "iLITH is a Microsoft Access database containing GIS capabilities that allows users to interact with a portion of the Indiana Department of Natural Resources (IDNR) Water-Well Record Database. iLITH differs from the IDNR database in that lithologic descriptions and drilling contractor names have been standardized, locational information for ~104,000 water-well logs has been verified, and the spatial information in the database has been standardized for use with USGS digital elevation data and US Census Bureau Tiger data. The iLITH graphical interface facilitates efficient interaction between the user and the database." Using Microsoft Access, queries were constructed that summed the total thickness of clay units for each well. Units with the following designations were included in the summation: "clay," "clay and gravel," "clay and sand," "clay and stone," "clay with gravel," "clay with gravel seams," "clay with sand," "clay with sand streaks," "mud," "mud and gravel," and "mud and sand." Some inconsistencies in the database were eliminated. The resulting table was then exported from Microsoft Access and imported into ESRI ArcView to construct a point shapefile.CLAY_ILITH_PTS_IN 为点形状文件（shapefile），呈现了从印第安纳州水井测井数据中推导得到的黏土总厚度。（该数据集为创建名为"CLAY_ILITH_IN"的网格提供了源数据，后者同样采用形状文件格式。）本数据集的数据源自印第安纳州地质调查局的iLITH数据库。印第安纳州地质调查局在其《公开报告研究00-8》（Open-File Study 00-8）中对iLITH数据库做出如下说明："iLITH是一款具备地理信息系统（GIS）功能的Microsoft Access数据库，支持用户与印第安纳州自然资源部（Indiana Department of Natural Resources, IDNR）的部分水井记录数据库进行交互。iLITH与IDNR数据库的区别在于，其岩性描述与钻井承包商名称均已实现标准化，约10.4万条水井测井数据的位置信息已完成核验，且数据库中的空间信息已完成标准化处理，可适配美国地质调查局（USGS）数字高程数据与美国人口普查局Tiger数据的使用需求。iLITH的图形用户界面可实现用户与数据库之间的高效交互。"研究人员通过Microsoft Access构建查询语句，对每口井的黏土类地层总厚度进行汇总计算。本次汇总包含以下岩性标识的地层："黏土（clay）"、"黏土与砾石（clay and gravel）"、"黏土与砂（clay and sand）"、"黏土与石块（clay and stone）"、"含砾黏土（clay with gravel）"、"含砾石夹层黏土（clay with gravel seams）"、"含砂黏土（clay with sand）"、"含砂纹黏土（clay with sand streaks）"、"泥（mud）"、"泥与砾石（mud and gravel）"以及"泥与砂（mud and sand）"。研究人员已剔除数据库中存在的部分不一致数据。最终生成的数据表从Microsoft Access中导出，并导入至ESRI ArcView软件中，以构建该点形状文件。