Chapter V: The Glacial Period

The Drift

Snow Fields and ice Sheets

The North American ice Sheets

The Work of glacier Ice

Erosive Work of Ice. Effect on Topography

Deposition by the Ice. Effect on Topography

Direction of ice Movement

Effect of Topography on Movement

Glacial Deposits

The ground Moraine

Constitution

Topography

Terminal Moraines

Topography of terminal Moraines

The terminal Moraine about Devil's Lake

The Moraine on the main Quartzite Range

Constitution of the marginal Ridge

The Slope of the upper Surface of the Ice at the Margin

Stratified Drift

Its Origin

Glacial Drainage

Stages in the History of an Ice Sheet

Deposits made by extraglacial Waters during the maximum Extension
of the Ice

At the Edge of the Ice, on Land

Beyond the Edge of the Ice, on Land

Deposits at and beyond the Edge of the Ice in standing Water

Deposits made by extraglacial Waters during the Retreat of the Ice

Deposits made by extraglacial Waters during the Advance of the Ice

Deposits made by subglacial Streams

Relations of stratified to unstratified Drift

Complexity of Relations

Classification of stratified Drift on the Basis of Position

Extraglacial Deposits

Supermorainic deposits

The submorainic (basal) Deposits

Intermorainic stratified Drift

Changes in Drainage effected by the Ice

While the Ice was on

Wisconsin Lake

Baraboo Lake

Devil's Lake in glacial Times

After the Ice had disappeared

Lakes

Existing Lakes

Changes in Streams

Skillett Creek

The Wisconsin

The Driftless Area

Contrast between glaciated and unglaciated Areas

Topography

Drainage

Mantle Rock

LIST OF ILLUSTRATIONS.

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PLATES.

Plate

Frontispiece. The Dalles of the Wisconsin

I. General map of the Devil's Lake region

II. Local map of the Devil's Lake region

III. Fig. 1--Ripple marks on a slab of sandstone
Fig. 2--Piece of Potsdam conglomerate

IV. Lower Narrows of the Baraboo

V. Devil's Lake notch

VI. East bluff of Devil's Lake

VII. East bluff at the Upper Narrows of the Baraboo near Ableman's

VIII. Vertical shear zone face of east bluff at Devil's Lake

IX. Massive quartzite in situ in road through Upper Narrows near
Ableman's

X. Brecciated quartzite

XI. Northwest wall of the Upper Narrows

XII. Steamboat Rock

XIII. Fig. 1--A very young valley
Fig. 2--A valley at later stage of development
Fig. 3--Young valleys

XIV. Fig. 1--Same valleys as shown in Pl. XIII, Fig. 3,
but at a later stage of development
Fig. 2--Same valleys as shown in Fig. 1 in later stage of
development

XV. Diagram illustrating how a hard inclined layer of rock
becomes a ridge in the process of degradation

XVI. Skillett Falls

XVII. A group of mounds on the plain northwest from Camp Douglas

XVIII. Castle Rock near Camp Douglas

XIX. Fig. 1--Sketch of a young valley
Fig. 2--Same valleys as shown in Fig. 1 in later stage of
development

XX. Fig. 1--Sketch of a part of a valley at a stage of
development corresponding to the cross section
shown in Figure 21
Fig. 2--Sketch of a section of the Baraboo valley

XXI. Cleopatra's Needle

XXII. Turk's Head

XXIII. Devil's Doorway

XXIV. Talus slope on east bluff of Devil's Lake

XXV. Dorward's Glen

XXVI. Natural Bridge near Denzer

XXVII. The Navy Yard

XXVIII. Chimney Rock

XXIX. An island in the Lower Dalles

XXX. View in Lower Dalles

XXXI. Stand Rock

XXXII. Petenwell Peak

XXXIII. North American ice sheet

XXXIV. Owl's Head

XXXV. Cut in glacial drift

XXXVI. Glaciated stones

XXXVII. Topographic map of a small area about Devil's Lake

XXXVIII. Distorted laminae of silt and clay

FIGURES IN TEXT.

Figure

1. Profile across the Baraboo quartzite ranges through Baraboo

2. Profile across the Baraboo ranges through Merrimac

Transcriber's note: There is no figure 3.

4. Diagram showing the structure of the quartzite

5. Diagram showing the relation of the Potsdam sandstone to the Baraboo
quartzite

6. Diagram illustrating effect of faulting on outcrop

7. Diagram showing the disposition of sediments about an island

8. The same as 7 after subsidence

9. Diagram showing relation of Potsdam conglomerate to quartzite at
Devil's Lake

10. Cross section of a delta

11. The geological formations of southern Wisconsin

12. A typical river system

13. Diagram illustrating the relations of ground water to streams

14. Diagram illustrating the shifting of divides

15. Diagram showing topography at the various stages of an erosion cycle

16. Diagram illustrating the development of rapids and falls

17. Sketch looking northwest from Camp Douglas

18. Diagrammatic cross section of a young valley

19. Diagrammatic profile of a young valley

20. Diagrammatic cross section of a valley in a later stage of
development

21. The same at a still later stage

22. Diagram illustrating the topographic effect or rejuvenation of a
stream by uplift

23. Normal profile of a valley bottom

24. Profile of a stream rejuvenated by uplift

25. Diagram illustrating monoclinal shifting

26. Diagram showing the relation of the Potsdam sandstone to the
quartzite at the Upper Narrows

27. Diagrammatic cross section of a field of ice and snow

28. Shape of an erosion hill before glaciation

29. The same after glaciation

30. Diagram showing the effect of a valley on the movement of ice

31. The same under different conditions

32. Diagram showing the relation of drift to the underlying rock where
the drift is thick

33. The same where the drift is relatively thin

34. Diagrammatic representation of the effect of a hill on the edge of
the ice

35. The same at a later stage of the ice advance

36. Map showing the relation of the ice lobes during the Wisconsin epoch
of the glacial period

37. Sketch of the terminal moraine topography east of Devil's Lake

38. Cut through the terminal moraine east of Kirkland

39. Cross section of the marginal ridge of the moraine on the south
slope of the Devil's nose

40. Cross section of the marginal ridge of the moraine on the crest of
the quartzite range

41. Morainic outwash plain

42. The same in other relations

43. Skillett Creek and its peculiarities

44. The Wisconsin valley near Kilbourn city

45. Drainage in the driftless area

46. Drainage in the glaciated area

47. Section in the driftless region showing relation of the soil to the
solid rock beneath