Jo Daviess County IL Bedrock Crevices

<p><b>Please see the individual layers below to access the detailed metadata.</b><br /></p><p>In order to support science-based water resource management, a systematic effort was undertaken to characterize the nature and function of the hydrogeology in Jo Daviess County, Illinois. Jo Daviess County is a karst area. Karst is a geologically and hydrologically integrated or interconnected and self-organizing network of landforms and subsurface large-scale, secondary porosity created by a combination of fractured carbonate bedrock, the movement of water into and through the rock body as part of the hydrologic cycle, and physical and chemical weathering (Panno, S.V. et al, 2017). Springs, cover-collapse sinkholes, crevices, and caves are among the defining features of a karst terrain; each of these features is found in Jo Daviess County. Examples of these features have been located in the field and characterized by scientists from the Illinois State Geological and Water Surveys (Prairie Research Institute, University of Illinois at Urbana-Champaign).</p><p>An unforeseen outcome of the 2012 summer drought that impacted the U.S. Midwest and adversely affected the health and vigor of agricultural crops was it provided a rare opportunity to examine the fractured, creviced, and buried bedrock surface of northwestern Illinois. Complex vegetated networks, referred to as ‘crop lines’, began to appear across the dry summer landscape of Jo Daviess County, Illinois, including adjacent western Stephenson County and southwestern Wisconsin. Primarily confined to alfalfa hay fields, the vegetated crop lines resulted from a combination of three factors: 1) the persistent extremely dry conditions, 2) a relatively thin (3 to 5 feet) overburden of unconsolidated deposits, and 3) a highly fractured and creviced bedrock surface comprised of Ordovician age Galena Dolomite.</p><p>Alfalfa’s vigorous root system, which may ultimately extend to depths of 6.1 m (20 feet) or more, enables it to obtain water and nutrients moving through bedrock crevices near the top of the karst aquifer, providing the necessary moisture during the 2012 summer drought to sustain the overlying healthy alfalfa plants, whereas the remaining field area exhibited stunted and sparse plant growth. The alfalfa plants forming the crop lines tended to grow denser, taller (0.5 m vs. 0.15 m), and greener than those in adjacent areas, were clearly visible from vertical aerial photographs, and provided a visual representation of the bedrock fracture pattern below. Work on this project was funded by the Illinois State Geological Survey.</p><p>The publications cited below provide background and context:</p><p>Panno, S.V. and D.E. Luman. Assessment of the geology and hydrogeology of two sites for a proposed large dairy facility in Jo Daviess County near Nora, IL. Illinois State Geological Survey Open File Series 2008-2, 2008. https://library.isgs.illinois.edu/Pubs/pdfs/ofs/2008/ofs2008-02.pdf</p><p> </p><p>Panno, S.V., Philip G. Millhouse, Randy W. Nyboer, Daryl Watson, Walton R. Kelly, Lisa M. Anderson, Curtis C. Albert, and Donald E. Luman. Guide to the Geology, Hydrogeology, History, Archaeology, and Biotic Ecology of the Driftless area of Northwestern Illinois, Jo Daviess County. Illinois State Geological Survey Guidebook 42, 2016. https://www.isgs.illinois.edu/publications/gb042</p><p> </p><p>Panno, S.V., Donald E. Luman, Walton R. Kelly, Timothy H. Larson, and Stephen J. Taylor. Karst of the Driftless Area of Jo Daviess County, Illinois. Circular 586, Illinois State Geological Survey, Prairie Research Institute, University of Illinois Urbana-Champaign, 2017. https://isgs.illinois.edu/maps/county-maps/karst-terrain/jo-daviess-0</p><div><br /></div><p><br /></p><div><br /></div>

<p><b>请点击下方各图层以查看详细元数据。</b><br /></p><p>为支撑基于科学的水资源管理，我们开展了系统性工作，以表征伊利诺伊州乔戴维斯县（Jo Daviess County）水文地质学的性质与功能。乔戴维斯县属于喀斯特（Karst）地貌区。喀斯特是一种由地质与水文过程整合、相互连通且自组织的地貌与地下大型次生孔隙网络，其形成过程包括裂隙碳酸盐岩基岩、水文循环中水体进入并穿过岩体，以及物理与化学风化作用（Panno, S.V. 等，2017）。泉眼、覆盖塌陷型落水洞、裂隙与洞穴均为喀斯特地貌的典型特征，上述特征在乔戴维斯县均有分布。伊利诺伊州地质与水调查局（伊利诺伊大学厄巴纳-香槟分校草原研究所）的科研人员已在野外定位了这些地貌特征并完成了表征工作。</p><p>2012年夏季干旱席卷美国中西部，对农作物健康与长势造成了负面影响，但其也带来了一项意外收获：为我们提供了难得的研究机会，得以考察伊利诺伊州西北部被裂隙、缝隙覆盖的埋藏基岩表面。在乔戴维斯县（包括邻近的斯蒂芬森县西部与威斯康星州西南部）的干燥夏季景观中，出现了被称为"作物带"的复杂植被网络。这类植被带主要分布在紫花苜蓿干草田中，其形成源于三大因素的共同作用：1）持续的极端干旱天气；2）厚度仅3至5英尺的松散沉积覆盖层；3）由奥陶纪年代的盖仑白云岩（Galena Dolomite）构成的高度裂隙化与缝隙化的基岩表面。</p><p>紫花苜蓿拥有发达的根系，最深可延伸至6.1米（20英尺）甚至更深，使其能够汲取喀斯特含水层顶部附近基岩裂隙中的水分与养分，为2012年夏季干旱期间的植株提供必要水分，从而维持了上方苜蓿的健康生长；而其余田块的植株则表现出生长迟缓、稀疏的状态。形成作物带的紫花苜蓿相较于周边区域的植株，长势更为茂密、更高（0.5米对比0.15米）、颜色更绿，可通过垂直航空摄影照片清晰辨识，直观展现了下方基岩的裂隙分布格局。本项目由伊利诺伊州地质调查局资助。</p><p>下述出版物为本研究提供了背景与参考依据：</p><p>Panno, S.V. 与 D.E. Luman. 伊利诺伊州诺拉附近乔戴维斯县拟建大型乳制品厂场地的地质与水文地质评估. 伊利诺伊州地质调查局公开文件系列2008-2, 2008. https://library.isgs.illinois.edu/Pubs/pdfs/ofs/2008/ofs2008-02.pdf</p><p> </p><p>Panno, S.V., Philip G. Millhouse, Randy W. Nyboer, Daryl Watson, Walton R. Kelly, Lisa M. Anderson, Curtis C. Albert, 及 Donald E. Luman. 伊利诺伊州西北部无冰碛区（Driftless Area）乔戴维斯县地质、水文地质、历史、考古与生物生态指南. 伊利诺伊州地质调查局指南手册42, 2016. https://www.isgs.illinois.edu/publications/gb042</p><p> </p><p>Panno, S.V., Donald E. Luman, Walton R. Kelly, Timothy H. Larson, 及 Stephen J. Taylor. 伊利诺伊州乔戴维斯县无冰碛区喀斯特地貌. 通报586, 伊利诺伊州地质调查局、伊利诺伊大学厄巴纳-香槟分校草原研究所, 2017. https://isgs.illinois.edu/maps/county-maps/karst-terrain/jo-daviess-0</p><div><br /></div><p><br /></p><div><br /></div>