R. H. WHITBECK. Contrasts between the Glaciated and the Driftless Portions of Wisconsin, Bull. Geogr. Soc., Philadelphia, vol. 9, 1911, pp. 114-123. Glacier gravings:— T. C. CHAMBERLIN. The Rock Scorings of the Great Ice Invasions, 7th Ann. Rept. U. S. Geol. Surv., 1888, pp. 147-248, pl. 8. The dispersion of the drift:— R. D. SALISBURY. Notes on the Dispersion of Drift Copper, Trans. Wis. Acad. Sci., etc., vol. 6, 1886, pp. 42-50, pl. N. S. SHALER. The Conditions of Erosion beneath Deep Glaciers, based upon a Study of the Bowlder Train from Iron Hill, Cumberland, Rhode Island, Bull. Mus. Comp. Zoöl. Harv. Coll., vol. 16, No. 11, 1893, pp. 185-225, pls. 1-4 and map. WILLIAM H. HOBBS. The Diamond Field of the Great Lakes, Jour. Geol., vol. 7, 1899, pp. 375-388, pls. 2 (also Rept. Smithson. Inst., 1901, pp. 359-366, pls. 1-3). Glacial features:— T. C. CHAMBERLIN. Preliminary Paper on the Terminal Moraine of the Second Glacial Epoch, 3d Ann. Rept. U. S. Geol. Surv., 1883, pp. 291-402, pls. 26-35. G. H. STONE. Glacial Gravels of Maine and their Associated Deposits, Mon. 34, U. S. Geol. Surv., 1899, pp. 489, pls. 52. W. C. ALDEN. The Delaven Lobe of the Lake Michigan Glacier of the Wisconsin Stage of Glaciation and Associated Phenomena. Prof. Pap. No. 34, U. S. Geol. Surv., 1904, pp. 106, pls. 15; The Drumlins of Southeastern Wisconsin, Bull. 273, U. S. Geol. Surv., 1905, pp. 46, pls. 9. W. M. DAVIS. Structure and Origin of Glacial Sand Plains, Bull. Geol. Soc. Am., vol. 1, 1890, pp. 196-202, pl. 3; The Subglacial Origin of Certain Eskers, Proc. Bost. Soc. Nat. Hist., vol. 35, 1892, pp. 477-499. F. P. GULLIVER. The Newtonville Sand Plain, Jour. Geol., vol. 1, 1893, pp. 803-812. CHAPTER XXIII GLACIAL LAKES WHICH MARKED THE DECLINE OF THE LAST ICE AGE [Illustration: FIG. 346.—The Illinois River where it passes through the outer moraine at Peoria, Illinois, showing the flood plain of the ancient stream as an elevated terrace into which the modern stream has cut its gorge (after Goldthwait).] =Interference of glaciers with drainage.=—Every advance and every retreat of a continental glacier has been marked by a complex series of episodes in the history of every river whose territory it has invaded. Whenever the valley was entered from the direction of its divide, the effect of the advancing ice front has generally been to swell the waters of the river into floods to which the present streams bear little resemblance (Fig. 346). Because of the excessive melting, this has been even more true of the ice retreat, but here _when the ice front retired up the valley_ toward the divide. A sufficiently striking example is furnished by the Wabash, Kaskaskia, Illinois, and other streams to the southward of the divide which surrounds the basin of the Great Lakes (Fig. 347). [Illustration: