ABSTRACT The Eagle Lake basin was formed by collapse of the ablating Lake Michigan lobe over a tunnel valley and subsequent reoccupation of the collapse basin by the lobe during local final phase of glaciation. Latest collapse occurred prior to about 16,250 but after 18,600 cal yr B.P. A hydrologically open lake occupied Eagle Lake basin from 16,250 cal yr B.P. to the present. The lake was described in 1834 by the original land survey, but was drained for agriculture by 1939.

Extract from beginning of chapter: Anyone who is studying dissected volcanoes and ancient lavas and breccia should have some acquaintance with active volcanoes and regions of modern volcanism. So I decided to visit Vesuvius and the Sicilian region, incidentally make the acquaintance of some of the British petrographers, and pay my respects to Rosenbusch in Heidelberg. By the end of February 1890, I was able to leave Washington for a two-month trip, going directly from New York to London via Southampton. Although I had never met Judd or Teall, they were hospitable enough, when they learned of my intention to stop in London on my way to the Continent, to invite me to come directly to their homes upon my arrival. Judd's note reached me before I left Washington, and Teall's caught me before I left the steamer at Southampton. It resulted in my spending a few days with Judd on my way out and in visiting Teall on the way back—a most memorable experience, quite as enlightening as the study of active volcanoes. IMPRESSIONS OF JOHN JUDD After a night at Charing Cross Hotel, I found Judd in his rooms in the “science schools,” 1 South Kensington, and received a most cordial welcome. Probably no British geologist equaled Judd in genial temperament and the ability to be entertaining. His manner was frank and outspoken; his attitude toward his colleagues was generous and not critical. He took an enthusiastic interest in petrography and expressed his opinions with such positiveness that one was led to believe

A numerical model of a spherical viscoelastic self-gravitating Earth has been used to predict the glacio-isostatic deformation of the Lake Michigan basin during late-glacial and postglacial times. Predictions of present rate of vertical movement agree well in trend but slightly exceed in magnitude the observed rate of tilting indicated by lake-level gauges. Predicted uplift curves for the four dominant outlets controlling the ancestral lakes of the Lake Michigan basin indicate an outlet chronology comparable to that proposed by glacial geologists despite the fact that the Chicago and Port Huron outlets are not predicted to be stable as is commonly believed. Predictions of tilting of the Algonquin shoreline match observations north of the Algonquin hinge line, but the predicted shoreline plunges below the present level of Lake Michigan at the hinge line location. In opposition to the commonly held belief in crustal stability south of the Algonquin hinge line, the predictions indicate considerable vertical movement there continuing to the present. If the predictions are correct, the subhorizontal shorelines south of the hinge line have been misinterpreted because the Glenwood shoreline, reported to be subhorizontal there, is predicted to be strongly tilted. Alternatively, correct interpretation of this shoreline implies serious deficiencies in the assumed ice-sheet history or Earth rheology used as input to the model.

Abstract Low-gradient streams and generally flat topography have always presented a problem of flooding within the Chicago area. As settlement expanded, the flooding produced greater and more serious results. As early as 1816, the city's leaders began major engineering work to solve these problems. The latest efforts toward a solution currently include a system of over 100 miles (161 km) of large-diameter tunnels in the Chicago area bedrock. These tunnels will intercept overflow from combined sanitary and stormwater systems and convey it to temporary storage reservoirs prior to its being pumped to sewage treatment facilities. Geologic investigations made during a study for the tunnel sites included test drilling and coring, geophysical logging of boreholes, laboratory testing of samples, seismic surveying, and testing for groundwater. The drilling, coring, and logging furnished data that have been of considerable help in mapping and describing the individual units of Silurian and Ordovician strata of the area. The seismic survey indicated numerous closed depressions on the surface of the bedrock and also sug-gested that several faults are present with displacements of 10 to 50 feet (3 to 15 m).

Abstract Geologists and engineers study beaches from different points of view. The geologist is interested in present-day earth processes in part for the light they shed on ancient sedimentary rocks, and in part to understand the interplay of matter and energy on and within the earth.