Geology - Bedrock Contacts

This dataset consists of the geologic contact lines for the Caldwell 7.5-minute Quadrangle. This polyline digital dataset, compiled through new detailed geologic mapping by the authors, represents the general distribution of geology for the Caldwell 7.5' quadrangle, Orange and Person Counties, North Carolina. This polyline file was used to develop North Carolina Geological Survey Open-File Report 2010-03. This file contains original North Carolina Geological Survey (NCGS) geologic mapping data generated by compiling detailed field observations during the period from August 2008 through June 2009 and September 2009 through May 2010. This polyline database delineates map units that are identified by general age and lithology through standard geologic mapping procedures. These data were mapped at a scale of 1:24,000 and are appropriate for use at this scale and smaller. Polylines are coded by line type (LINETYPE). This dataset contains inferred and concealed contact lines. This is the definition for the inferred polylines: A polyline that indicates the interpreted geologic contact between map units, determined based on available station data. A physical contact was not observed in the field. The concealed contact lines were obscured beneath the Quaternary alluvium.本数据集包含考德威尔（Caldwell）7.5分幅地形图幅（7.5-minute Quadrangle）的地质接触线。本折线型数字数据集由作者通过全新详细地质填图编制而成，完整呈现了北卡罗来纳州奥兰治县与珀森县境内考德威尔7.5分幅地形图幅的地质总体分布情况。该折线文件曾用于编制《北卡罗来纳州地质调查局公开报告2010-03》（North Carolina Geological Survey Open-File Report 2010-03）。本文件包含北卡罗来纳州地质调查局（North Carolina Geological Survey, NCGS）的原始地质填图数据，这些数据源自2008年8月至2009年6月、2009年9月至2010年5月期间收集的详细野外观测资料。该折线数据库通过标准地质填图流程，圈定了以大致年代与岩性为识别依据的图幅单元。本数据以1:24000比例尺完成填图，适用于该比例尺及更小比例尺的相关工作。折线通过线型（LINETYPE）进行编码。本数据集包含推断型与隐蔽型地质接触线。推断型折线的定义如下：指基于现有测站数据解译得到的、代表图幅单元之间地质接触关系的折线，野外未观测到实际物理接触界面。隐蔽型接触线则指被第四纪冲积层（Quaternary alluvium）所覆盖的地质接触线。