Carol F. Sawyer

Tree-Ring Dating of Snow Avalanches in Glacier National Park, Montana, USA

Snow avalanches are major hazards to humans occupying or visiting mountain ranges around the world. Accurate dating of past high-magnitude snow avalanches is important for a better understanding of their frequency, extent, and climatic driving factors. As climates change, prediction of shifts in avalanche frequency and/or magnitude are better enabled when a thorough understanding of past avalanche occurrences exists.

The Use of Historical Picture Postcards as Photographic Sources for Examining Environmental Change: Promises and Problems

Abstract Researchers and teachers who wish to illustrate environmental change over extended periods of time require imagery that pre‐dates widespread aerial photography and satellite products. Historical ground‐based photographs are difficult and expensive to acquire. A low‐cost alternative to acquiring historical photographs is the use of antique picture postcards, which are relatively cheap and more widely available. Problems exist, however, with the use of antique picture postcards for establishing baseline conditions in a study of environmental change. The original photographs on which picture postcards are based were frequently modified by card publishers, such that the conditions on the cards do not represent a true view of the landscape of the period. We illustrate several examples of such distortions from study sites in Glacier and Yellowstone National Parks, two large U.S. national parks for which antique picture postcards are still widely available.

Using Webcams to Show Change and Movement in the Physical Environment.

Environmental change is ideally taught through field observations; however, leaving the classroom is often unrealistic due to financial and logistical constraints. The Internet offers several feasible alternatives using webcams that instructors can use to illustrate a variety of geographic examples and exercises for students. This article explores the use of webcams for illustrating important spatial concepts of temporal change and movement, and offers several examples of classroom use of webcams. It shows how to find webcams and provides useful webcam site addresses. The article offers a webcam-based exercise for students that reinforces basic physical geography concepts.

A chronology of high‐magnitude snow avalanches reconstructed from archived newspapers

Purpose – Using local historical data, the purpose of this paper is to compile a chronology of high‐magnitude snow avalanches to illustrate the effectiveness of information published in newspapers in assisting the management of natural hazards.Design/methodology/approach – Major transportation lines parallel the southern boundary of Glacier National Park, Montana, USA, an area where snow avalanches occur frequently and occasionally block transportation corridors. A 1986 study presented an avalanche chronology for the study area based on information collected from the 1946 to 1982 issues of a local weekly newspaper. We extend that existing data set here by using the same newspaper, recording avalanche occurrences and impacts reported in the newspaper from 1982 to 2005.Findings – The newly updated chronology is presented, with trends and temporal patterns for the entire 1946‐2005 data set analyzed. A decrease in reported avalanches, from the 1960s onward, is noted. Additionally, reported avalanches shifted ...

Chapter 4 Geomorphic Patterns and Processes at Alpine Treeline

Abstract Geomorphic patterns and processes affect alpine treeline at a variety of spatial and temporal scales. At coarse scales, snow avalanches and debris flows are widespread and create disturbance treelines elevationally depressed well below the climate-controlled alpine treeline. At medium scales, turf-banked terraces create tread-and-riser topography that is a difficult landscape for a tree seedling to survive upon because of exposure to wind, dryness, and impenetrable surfaces. At fine scales, turf exfoliation of the fronts of turf-banked risers, and boulders, offer microsites where tree seedlings may find shelter and are able to gain a foothold in the alpine tundra; conversely, however, surfaces of needle-ice pans and frost heaving associated with miniature patterned ground production are associated with sites inimicable to seedling establishment or survival. The geomorphic role of animals at treeline may assist or hinder seedling survival.