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Geology topics

J.E. Colwell

Publications and source records attributed to J.E. Colwell.

4 recordsLinked to original sources
USGS2010

An evolving view of Saturn’s dynamic rings

We review our understanding of Saturn’s rings after nearly 6 years of observations by the Cassini spacecraft. Saturn’s rings are composed mostly of water ice but also contain an undetermined reddish contaminant. The rings exhibit a range of structure across many spatial scales; some of this involves the interplay of the fluid nature and the self-gravity of innumerable orbiting centimeter- to meter-sized particles, and the effects of several peripheral and embedded moonlets, but much remains unexplained. A few aspects of ring structure change on time scales as short as days. It remains unclear whether the vigorous evolutionary processes to which the rings are subject imply a much younger age than that of the solar system. Processes on view at Saturn have parallels in circumstellar disks.

Science↗
USGS1980

Enumeration of prairie wetlands with Landsat and aircraft data

A method is described for making an estimate of wetland numbers in the glaciated prairie region. A double-phase sampling approach is used which consists of first making a total census of wetlands using Landsat data, and then adjusting the Landsat results on the basis of samples derived from high resolution aircraft data. The method is relatively simple to use and has general applicability for estimating habitat features not consistently detectable or resolvable on Landsat imagery because their size range includes features less than the resolution capability of the satellite's sensor.

Photogrammetric Engineering and Remote Sensing↗
USGS1978

Use of Landsat data to assess waterfowl habitat quality

This report is a discussion of the feasibility of using Landsat data to generate information of value for effective management of migratory waterfowl. Effective management of waterfowl includes regulating waterfowl populations through hunting regulations and habitat management. This report examines the ability to analyze annual production by monitoring the number of breeding and brood ponds that are present, and the ability to assess waterfowl habitat based on the various relationships between ponds and the surrounding upland terrain types. The basic conclusions of this report are that: 1) Landsat data can be used to improve estimates of pond numbers which may be correlated with duck production; and 2) Landsat data can be used to generate information on terrain types which subsequently can be used to assess relative waterfowl habitat quality.

Report↗