Aquifer Characteristics Of Glacial Drift

This data set was derived from the 1981 publication of the Hydrological Atlas of Michigan plate 26. Three plates of the Aquifer Characteristics of Glacial Drift map were scanned, geo-rectified and used as a backdrop in the digitizing of this polygon vector file. Aquifer Characteristics of the Glacial Drift map for Michigan was developed from the 1:500,000 maps of the Surface Formations of the Northern and Southern Peninsulas of Michigan (Martin, 1955). Four major aquifer units were defined for the glacial drift, and one unit (unit III) was subdivided into two sub-units for the Southern Peninsula (see explanation). The Northern Peninsula portion of the Aquifer Characteristics map was prepared from glacial drift and/or ground-water availability maps in County Progress Reports, and a Seafarer Site Survey (see References). The mapped surface formations presented in these reports were reinterpreted and assigned to the four major aquifer nits established for this map. The Southern Peninsula portion of the Aquifer Characteristics map is based on a reinterpretation of the units delineated on the Surface Formations of the Southern Peninsula of Michigan (Martin, 1955), Landform Units in Northeastern Lower Michigan (Burgis, 1977), and Aquifer Vulnerability to Surface Contamination in Michigan (Dept. of Public Health, 1980). In addition, water well records were examined to determine the relationship between the drift stratigraphy and the four major aquifer units used for this map. The analysis of well records was done initially for type areas of clearly distinguished surface glacial deposits. After it was established that a general correlation exists, approximately 39,300 water and oil and gas well records were examined, with particular attention to those which penetrated thick sections of drift. Well records from all townships on 10 east-west transects and one north-south transect were inspected: Townships 5S, 1N, 5N, 10N, 14N, 20N, 24N, 32N, and 37N, and 4W. In addition, Ionia, Clinton, Van Buren, Cass, Sanilac, St. Clair, Alpena, Macomb, Bay, Monroe, Ottawa and Muskegon Counties were checked in more detail. Finally selected deep wells and oil and gas wells with detailed records of the drift were examined to determine the characteristics of the drift at depth. In general, the drift below the typical depths of wells was found to have characteristics similar to the shallower drift. Locally, as in Ottawa and Muskegon Counties and in a broad area of south-central Michigan, parts of Barry, Clinton, Eaton, Ingham, Livingston, Oakland, Shiawassee, Genesee, Lapeer, Sanilac and Tuscola Counties, small discontinuous areas exist where the deeper drift is not an aquifer. Aquifer Characteristics Explanation IV Drift may be an unconfined aquifer to bedrockNot possible to delineate from available data III A Drift usually unconfined at or near the surface, generally consists of interbedded aquifers, aquicludes, and aquitards at depth III B Drift may or may not be an aquifer at or near the surface. Drift generally consists of interbedded aquifers, aquicludes, and aquitards at dethhs Aquifer characteristics generally conform to category III, but drift may not be an aquifer in small discontinuous areas. II Drift generally not an aquifer, may include thin interbedded aquifers at depth I Thin drift (0-30 feet) overlying bedrock For questions on this data please reach out to Mark Snow at [e-mail]本数据集源自1981年版《密歇根水文图集》（Hydrological Atlas of Michigan）第26图幅。本次共扫描3幅冰川沉积物含水层特征图（Aquifer Characteristics of Glacial Drift），经地理校正后作为底图，用于本多边形矢量文件（polygon vector file）的数字化工作。 密歇根冰川沉积物含水层特征图的编制，基于1:500,000比例尺的密歇根北部半岛与南部半岛地表地层图（Martin, 1955）。本次研究为冰川沉积物划定了4个主要含水层单元，并针对南部半岛将其中第III单元细分为2个亚单元（详见说明）。 该含水层特征图的北部半岛部分，由县级进展报告中的冰川沉积物及/或地下水可利用性图，以及《海员场地调查》（Seafarer Site Survey，详见参考文献）编制而成。报告中所绘制的地表地层经重新解译后，被归入本次图集设定的4个主要含水层单元。 南部半岛部分则基于对以下资料的重新解译：《密歇根南部半岛地表地层图》（Martin, 1955）、《密歇根下半岛东北部地貌单元》（Burgis, 1977）以及《密歇根含水层对地表污染的脆弱性》（密歇根公共卫生部, 1980）。此外，本次研究还核查了水井记录，以明确冰川沉积地层与本图集所用4个主要含水层单元之间的对应关系。 水井记录的分析最初针对地表冰川沉积特征清晰的典型区域开展。在确认存在普遍相关性后，研究人员共核查了约39300口水井与油气井记录，重点关注穿透较厚冰川沉积层的井位。核查范围覆盖10条东西向样带与1条南北向样带所涉及的全部镇区，包括镇区5S、1N、5N、10N、14N、20N、24N、32N、37N以及4W。此外，还对艾奥尼亚县、克林顿县、范布伦县、卡斯县、萨尼拉克县、圣克莱尔县、阿尔皮纳县、马科姆县、贝县、门罗县、渥太华县以及马斯基根县进行了更为细致的核查。 最终，研究人员选取了带有详细冰川沉积记录的深井与油气井，以分析深部冰川沉积的特征。总体而言，超出典型井深的冰川沉积层，其特征与浅层冰川沉积层相似。局部区域，如渥太华县与马斯基根县，以及密歇根中南部的大片区域（包括巴里县、克林顿县、伊顿县、英厄姆县、利文斯顿县、奥克兰县、希亚瓦西县、杰纳西县、莱佩尔县、萨尼拉克县与图斯克拉县），存在小片不连续区域，其中深部冰川沉积层并非含水层。 ### 含水层特征说明 IV 冰川沉积可形成直达基岩的无压含水层（unconfined aquifer），无法根据现有数据圈定具体范围 III A 冰川沉积在地表或近地表处通常为无压含水层，深部一般由互层状的含水层、隔水层（aquiclude）与弱透水层（aquitard）组成 III B 冰川沉积在地表或近地表处可能为含水层，也可能不是。深部一般由互层状的含水层、隔水层与弱透水层组成。其含水层特征总体符合III类，但在小片不连续区域内，冰川沉积可能并非含水层 II 冰川沉积总体并非含水层，深部可能包含薄层互层状含水层 I 薄冰川沉积层（0~30英尺）覆盖于基岩之上 若对本数据集有任何疑问，请联系Mark Snow，邮箱：[e-mail]