Traveling by the New York Central Railway, we follow up the Mohawk outlet of the glacial lakes Iroquois and Algonquin ([334]), first skirting upon the east the great sills of intrusive basalt known as the Palisades, with their markedly columnar jointing and intersections by numerous faults. Above Peekskill we enter the picturesque narrows of the river ([174]), cut in the hard crystalline rocks of the Highlands. Entering the Mohawk Valley, we pass Syracuse with limestone caverns and well-oriented joints widened by solution through the agency of the descending ground water ([181], [pl. 6 B]). A branch line to the southwest reaches the vicinity of Cayuga Lake and Ithaca, where are well-oriented joints which have controlled the drainage directions, and there is also a typical strath ([55], [87], [428]).
To Niagara Falls at least a day should be allotted for the “gorge ride” by trolley car, thus making the complete circuit of the brink of the gorge with interruptions and local studies at all important points ([352-366], [pl. 23 A]). From Niagara Falls over the Michigan Central Railway we reach Detroit on the present outlet of the upper Great Lakes as well as of the later Lake Algonquin ([334]). From this city as a center a trip is made by electric railway to Ypsilanti and Ann Arbor, across the bottoms of the early glacial lakes from the first Maumee to Warren ([330-333]). The strong Whittlesey beach is encountered at the little station of Ridge Road, and one of the Maumee beaches on Summer Street in Ypsilanti. The city of Ypsilanti is built upon a terrace ([165]) of the Huron River, and another terrace in the same series is crossed by the electric line. In an excursion of a few miles down the river, passing meanders ([164-165]) and ox-bow lakes ([165], [415]), is found an interesting case of stream capture near the little village of Rawsonville ([175]. See Isaiah Bowman, Jour. Geol., Vol. 12, 1904, pp. 326-334).
Continuing our journey from Ypsilanti over a high moraine ([312]), Ann Arbor is reached, built upon the level plain of outwash with fosses sometimes separating it from the moraine ([281], [314]). Upon the campus of the university are great bowlders of jasper conglomerate and jaspilite, which were transported from the north by the continental glacier ([305]). Across the river from the Michigan Central station and behind the little church is a delta formed in one of the glacial lakes Maumee and here opened in section ([168]). West of the city is a great valley which was the former course of the Huron River when thus diverted by the continental glacier lying to the eastward of Ann Arbor—border drainage (see Ann Arbor folio by the U. S. G. S., and, further, R. C. Allen and I. D. Scott, An Aid to Geological Field Studies in the Vicinity of Ann Arbor, George Wahr, publisher, Ann Arbor).
Returning to Detroit (M. C. Ry.), the great Sibley quarries in limestone near Trenton may be visited. They display perfect jointing, numerous fossils, and especially well-glaciated surfaces interrupted by deep troughs and showing striæ of several glaciations ([304]). From Detroit the journey is continued by steamer to Mackinac Island in the strait connecting Lakes Michigan and Huron, passing on the way through the peculiar delta of the St. Clair River ([431]), and coming in view of the notched headlands, which are a monument to the post-glacial uplift of the glaciated area ([250], [341]). A day is spent at Mackinac Island and St. Ignace in order to study with some care these uplifted strands of the late glacial lakes ([341-344]). Chicago may now be reached either by steamer or by rail, and in its vicinity we may see the elevated beaches and the ancient outlet of Lake Chicago ([331-332], [347], [pl. 22 A]. See Chicago Folio, U. S. G. S.). By the Chicago and Northwestern Railway the area of recessional moraines and intermediate outwash plains, and later that of the drumlins, are crossed in journeying to Madison, Wisconsin. By examination of the maps on pages 308 and 317 in connection with the larger scale atlas sheets of the United States Geological Survey (Janesville, Evansville, and Madison sheets), this car journey can be made most instructive in gaining familiarity with the characteristic glacial features, and this study is continued to special advantage in excursions about Madison as a center ([316-317], [407]). This is the more true since at numerous localities in the vicinity of Madison the well-striated glacier pavement is exposed for comparison of the striæ as regards direction with the axes of the several types of glacial features.
An especially instructive excursion may be made by carriage in a single day to the “driftless area” some twelve miles west of the city. Before reaching it we cross in alternation a series of recessional terminal moraines ([pl. 17 C]) and outwash plains, and near Cross Plains encounter the partially dissected upland with its arborescent drainage and even sky line ([298], [300-301], [312-313], [pl. 16 A] and [B]). Typical shore formations ([233], [241], [242]) are studied to advantage about Lake Mendota in a walking trip to and beyond Picnic Point, where are found the best ice ramparts ([431-434]. See Buckley, Trans. Wis. Acad. Sci., Vol. 13, pp. 141-162, pls. 18).
Our journey is now continued over the Chicago and Northwestern Railway to Devils Lake near Baraboo, where we cross a salient of the driftless area, within which lies Devils Lake, imprisoned in a former valley of the Wisconsin River, since diverted to another course as a result of the glacial invasion ([312-313]). The valley here is a former narrows in hard quartzite ([466]), which towers above the lake in unstable chimneys ([300]), such as the Devils Tower, but such remnants are not found on the other side of the moraine, being there replaced by rounded rock shoulders. Just north of the lake the marginal moraine which blocks the valley is so characteristic as to merit special study ([pl. 17 C]). Only a few miles northward along the railway from Devils Lake is Ableman, where, exposed in a high cliff, the hard purple quartzite with beautiful ripple marks to reveal its plane of sedimentation ([pl. 11 A]) dips vertically, and is overlain by horizontally bedded yellow sandstone. The marked angular unconformity which is thus displayed is further made evident by a basal layer of conglomerate ([463]) in the sandstone ([51-53]). Here also are deposits of loess along the river, which display their vertical joint surfaces ([207]). An excellent geological guide to this interesting district and that of the neighboring “Dalles” of the Wisconsin River has been written by Salisbury and Atwood (The Geography of the Region about Devils Lake and the Dalles of the Wisconsin, etc., Bull. 5, Wis. Geol. and Nat. Hist. Surv., 1900, pp. 151, pls. 38, figs. 47).
If we have taken a conveyance at Devils Lake for Ableman, we may continue in the same manner to Kilbourn, where begin the picturesque Dalles of the Wisconsin River—here a young gorge cut in sandstone, because the Wisconsin was diverted from its old valley to border drainage at the edge of the driftless area ([300], [321]). The side cañons of the river, through their abrupt zigzags, reveal the control of their courses by the joint system ([224]). In the journey up the rapids by steamer to inspect the Dalles, we observe many beautiful examples of cross bedding in the sandstone ([37]).
From Kilbourn we continue our journey to Minneapolis over the Chicago, Milwaukee, and St. Paul Railway, and near Camp Douglas are over a peneplain, out of which rise prominent monadnocks ([171]). At La Crosse the Mississippi River is reached, flowing beneath bluffs of sandstone which are capped by loess ([207]). The meanderings and the numerous cut-offs of the Mississippi may be observed to the left ([415]). Lake Pepin is a side-delta lake blocked by the deposits of the Chippewa River ([419]).
From Minneapolis an excursion is made to Fort Snelling to view the young gorge of the Mississippi, cut by the Falls of St. Anthony for a distance of about eight miles in manner similar to that of the seven miles of Niagara gorge ([354]), and to compare this narrow gorge with the broad valley of the Warren River which drained Lake Agassiz ([327]). Somewhat farther up the Warren River are examples of saucer lakes ([416]).