Abstract Coralville Lake (Fig. 1) was authorized under the Flood Control Act of 1938 as a means of moderating stream flow on the Iowa River. Construction of the dam was begun in 1949, thendelayed by the Korean conflict, and consequently not completed until 1958. Coralville Dam regulates runoff from 3,084 mi 2 (8,018 km 2 ) of land upstream, providing flood protection to 1,703 mi 2 (4,428 km 2 ) of the Iowa River Valley below the dam. The U.S. Army Corps of Engineers maintains Coralville Lake asa multiple-use project providing primary benefits in flood control and low-flow augmentation, and secondary benefits in recreation, fish and wildlife management, forest management, and waterquality improvement. Lake MacBride (Fig. 1) is a subimpoundment of Coralville Lake. The lake and surrounding land compriseLake MacBride State Park, which is managed by he Iowa Conservation Commission. Exposures along the valley walls of that portion of the IowaRiver which comprises Coralville Lake, afford one the opportunity to examine at numerous points along its extent the upper most portion of the Wapsipinicon Formation and the entire Cedar Valley Formation. Excellent exposures of the Coralville Member of the Cedar Valley Formation can also be seen in the valley walls of the Iowa River in Iowa City (Witzke, 1984a).

ABSTRACT The Minneapolis Chain of Lakes is a focal point of natural beauty in the heart of the city. Given the recreational and aesthetic imperative, these urban waterbodies have for decades been heavily managed for water quality and lake level. In the early stages of development of Minneapolis’ civic infrastructure, the area’s lakes and streams, as well as the Mississippi River, were given special consideration for preservation. This did not, however, mean that the lakes were preserved in their “natural” state, for they were connected by channels, dredged and filled to turn wetlands into open water and dry land, and even reshaped to better conform to the prevailing fashion of design. These manipulations had dramatic effects on the Chain’s smallest lake, Brownie, which became meromictic after a rapid drop in lake level caused by ditching across the divide to Cedar Lake. The lakes and surrounding area were important sources of subsistence for Dakota and Ojibwe people through the middle of the nineteenth century, and some of the earliest substantive interactions between missionaries and Native Americans in Minnesota played out around the Chain of Lakes and nearby Mississippi River valley. The relative orientation of the lakes (and of other groups of lakes in the Twin Cities), and some lakes’ unusual depths relative to surface areas, result from their formation by melting of ice blocks buried in valley train fill during final retreat of the Laurentide ice sheet. Below tens to hundreds of feet of glacial material, mapping of bedrock surfaces indicates the presence of paleo–Mississippi River channels dating from at least two previous interglacials. The integration of multiple subdisciplines of geology and of various basic sciences within paleolimnology and limnogeology, as well as the relevance to students of historical and environmental information, makes lake sediment studies well suited to hands-on, place-based educational approaches as stand-alone courses or laboratories for a number of different core curriculum and nonmajor classes.

ABSTRACT One of the areas of highest coastal erosion along the Texas coast is located in the deltaic headland coastal segment of the Brazos River in the vicinity of Sargent Beach. Because of this erosion, a section of the Gulf Intracoastal Waterway (GIWW) from Cedar Lakes to East Matagorda Bay is in danger of intrusion from breaching of the narrow (less than 300 m wide) shorefront. Owing to its deltaic origin, the beach is composed of cohesive fine grained clay and silt material, overlain by a narrow layer of coastal peat and topped by a thin veneer of fine grained quartz beach sand with a high percentage of shell fragments. The northeastern half of the study area has an average erosion rate of 6.7 m/yr and has a thin sandy flat sloping beach over the clay deposit. The southwestern section has up to a meter high clay bluffs outcropping into the surf zone and has an average 11 m/yr erosion rate. It is speculated that this high erosion rate is a result of intermittent wave cutting of large chunks of the clay bluff material. The overall erosion rate along this coast is due to a general lack of sand.