This page provides lists the main points of and gives links to figures used in two lectures in Dr. Bruce Railsback's GEOL 1121 class at the University of Georgia. This page is not intended as a set of lecture notes, and it cannot substitute for a set of lecture notes. Familiarity with this page alone will not assure satisfactory grades on exams in the course.

Lectures 33, 34, and 35 (April 17, 19, and 22, 2002): Landscapes and Their Histories

Brief outline of these lectures:
none      

Main point of these lectures:
The point of these two lectures is to look at landscapes and see what they tell us about their past. For the pedagogically inclined, the point is to develop skills in interpreting visual information. Class participation will be required.

Points made along the way:
Dendritic drainage systems in modern rainless deserts suggest wetter climates in the past.
Dendritic drainage systems flooded by the ocean reflect sea level rise.
Landscapes that are flat overall but have pronounced gullies or valleys can be interpreted as previously flat landscapes through which streams have cut down, perhaps because of a drop in their base level.
Landscapes in which cirques and glacial valleys stand in sharp contrast to surroundng rolling topography can be interpreted as having been generally smooth rolling landscapes prior to glaciation.
U-shaped valleys are commonly modified after glaciation by rockfalls and other mass wasting because the steep sides of those valleys are unstable.
Straight valleys cutting across landscapes commonly result from faults.
Flat-bottomed valleys in mountain regions suggest that earlier deeper valleys have been filled in with sediments that makes up their present valley floors.
Erosion from mountains commonly generates broad plains of sediments downslope from those mountains. Subsequent erosion of those plains commonly leads to parallel drainage systems.
Rivers that cut across ridges, rather than flowing between those ridges, are river systems that existed prior to uplift of the ridges. These are called "superposed" rivers.
Sinkholes in arid landscapes commonly reflect wetter conditions in the past.

Some of the images used in these lectures:
This is not a complete set of all the images used in lecture, because copyright restrictions prevent the distribution of some images on the World-Wide Web. More will be added as they become available.
Central Sahara overview
Higher-resolution view within previous image
The coast of Guinea-Bissau
A canyon along the Glen Coe valley, western Scotland
A valley above the Glen Coe valley, western Scotland
Ben Nevis et al., western Scotland
A hillside in western Scotland
A mountain view in eastern Scotland
A high-altitude aerial photograph from western China
A mountain view in Kyrgyzstan
A Landsat view of eastern Australia near Sydney
A New Zealand landscape
A shuttle-based radar-generated image from western Argentina
Aerial photography of Mobjack Bay, Virginia, U.S.A.
Aerial photography of Annapolis, Maryland, U.S.A.
Aerial photography of Norfolk, Virginia, U.S.A.
The Susquehanna Valley, Pennsylvania, U.S.A.
Digital shaded relief map of the continental U.S.
A digital color topographic image of the Midwest - an overview of the next five images
A digital color topographic image of the Coteau de Prairie region
A digital color topographic image of southwest Wisconsin
A digital color topographic image of Missouri and southern Iowa
A digital color topographic image of Iowa
A digital color topographic image of South Dakota, Nebraska, and Kansas
Satellite image of the Grand Canyon
     Satellite image of the Grand Canyon - northeast section
     Satellite image of the Grand Canyon - southwest section
Mesa Verde, Colorado
near Mesa Verde
Monument Valley, Utah and Arizona
Canyon Rims, La Salle Junction, Utah
Marble Canyon, Arizona (!)
Chaco River and Hogback Mountain, New Mexico
Holes in the ground in Arizona
Loops in the San Juan River in Utah
A landscape in California
A valley in Glacier National Park
A valley in Yosemite National Park
Aerial view in northern Utah, U.S.A.
Feature near Binghan, Utah, U.S.A.
The same feature in more detail
Figure description

Reading assignment: None.


Next Lecture
Email to Railsback (rlsbk@gly.uga.edu)
Railsback's main 1121 web page
Railsback's main web page
UGA Geology Department web page