ABSTRACT The Indiana Dunes is a name commonly used for the eastern part of the Calumet Lacustrine Plain, generally referring to the large dunes along the coast from Gary, Indiana, eastward to the Michigan state line. However, the Calumet Lacustrine Plain also contains complex coastal landscapes associated with late Wisconsin to Holocene phases of ancestral Lake Michigan (e.g., mainland-attached beaches, barrier beaches, spits), including those formed during quasi-periodic decadal and shorter-term waterlevel variability that characterize modern Lake Michigan (e.g., beach ridges, dunes, interdunal wetlands). Major industrial development and other human activities have impacted the Calumet Lacustrine Plain, often altering these landscapes beyond recognition. Today, geological and paleoenvironmental data are sought to inform regional environmental restoration and management efforts and to increase the resiliency of the coastal landscape to ongoing disturbances. During this field trip, we will examine the relict shorelines and their associated nearshore and onshore features and deposits across the Indiana portion of the Calumet Lacustrine Plain. These features and deposits record the dynamic interaction between coastal processes of Lake Michigan, lake-level change, and long-term longshore sediment transport during the past 15,000 yr. Participants will examine the modern beach, the extensive beach-ridge record of the Tolleston Beach strandplain, a relict dune field, and the large dunes of the modern shoreline, including Mount Baldy. At Mount Baldy, we will focus on the landscape response to human modification of the shoreline. We will also explore the science behind dune decomposition chimneys—collapse features that caused a 6-yr-old boy to become buried more than 3.5 m below the dune surface in 2013 and highlighted a previously unrecognized geologic hazard.

ABSTRACT The Great Miami Buried Valley Aquifer system (GMBVAS) is a U.S. EPA–designated sole-source aquifer for most of the ~2.3 million residents of the Great Miami River basin. The aquifer system is similar to many of the glacial outwash–alluvial aquifers found throughout the southern Midwestern United States: a valley deeply incised into bedrock by meltwater from repeated glaciations, subsequently aggraded with glacial outwash, lake clays, tills, and post-glacial alluvium. These aquifers are often immediately adjacent to or below modern streams with which they are hydrologically connected. Because of the exchange of water between the aquifer and surface streams, they must be considered two parts of a single hydrogeologic system; anything impacting one part will impact the other. Because virtually all water is recycled, public water suppliers, agricultural users, and industrial users withdraw water from the GMBVAS, then discharge the used water to the next downstream consumer. For example, agricultural runoff and municipal wastewater enter the Great Miami River. River water recharges the aquifer near well fields through induced infiltration. Municipalities, agriculture, and industry pump groundwater from the aquifer and discharge some of the water back into the river as a return flow. Sound water management requires balancing the needs of these diverse users. Agriculture, particularly in the upper Great Miami basin, is a major source of revenue and jobs but requires heavy application of nutrients and herbicides. Sand and gravel quarrying in the Great Miami basin is critical for construction and infrastructure but also removes vast amounts of aquifer material. Not only is healthy reliable groundwater important for the public water supply, it is also essential to bottling facilities, distilleries, pharmaceutical companies, and other water-dependent industries that have been attracted to the area. This field trip explores the GMBVAS, its uses, its interaction with Great Miami River, and the contrasting needs of the people and businesses that depend on it.