Three broad geologic categories dominate the scene: dark volcanics; alteration products derived from these; and the limestone mountain. The Landsat thermal band 6 image

greatly simplifies the apparent scene content. The warmest areas (shown in lighter tones in keeping with the convention that hot is displayed in whites and light grays and cold in dark tones) are largely associated with the volcanics, most of which are dark basalts. These are imperfect black bodies that absorb much of the solar radiation and re-emit as strong radiators. The altered zones are mostly presented in dark tones, implying that less solar energy is "soaked up" so that they are marked by lower radiant temperatures. The limestones, in the field grayish surfaces with superficial brownish-red alteration, appear as moderately light tones hard to distinguish from the volcanic expressions.

August 22, 1982 shows the familiar east half of Lake Erie and the western part of Lake Ontario. The land appears moderately cool (darker tones), with little detail, although the cities of Buffalo (east tip of Lake Erie), Toronto (top center) and Hamilton, Ontario (west end of Lake Ontario; locally hot because of steel mill effluents) may be discernible on your monitor from street patterns and slightly lighter (warmer) tones. A mottled pattern of variably warmer bands characterizes Lake Ontario; these are related to thermal overturning effects (thermoclines) possible in this deeper (237 m [782 ft]) lake. Lake Erie is uniformly "hot" because its shallowness (less than 67 m [220 ft]) inhibits this type of circulation. Warm rivers, such as the Niagara connecting the two lakes, stand in contrast to the land.

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