Map Sources

The Atlas maps are composed of several layers of which there are two broad categories: thematic and base layers. Find below a description of each of the map layers. The layer source is included in the metadata.

Thematic Map Layers

Major Volcanoes

Locations and significant eruption dates for selected volcanoes and volcanic complexes in Canada and the United States to 1999. Data from: Catalogue of Canadian volcanoes, Geological Survey of Canada, the Alaska Volcano Observatory and the Cascades Volcano Observatory of the United States Geological Survey.

Significant Accumulation of Volcanic Ash

The distribution of volcanic ash (tephra) is from a selection of volcanic eruptions in Canada and the United States in the last 12 000 years. The areas represent tephra accumulations of at least 0.5 cm. The areas are extrapolated from known ash deposits. The eruptions dates are estimated using radiocarbon dating techniques and may be subject to refinement over time. Data from: Dr. Catherine Hickson, Geological Survey of Canada, the Alaska Volcano Observatory and the Cascades Volcano Observatory of the United States Geological Survey.

Base Map Layers

Atlas of Canada Framework Layers

Base map components are features that provide a geographic context for the thematic data shown on Atlas of Canada maps. These features include rivers, lakes, administrative boundaries, populated places, roads and rail lines. All of the Atlas of Canada base map components are available for immediate free download in five scales and in a number of data exchange formats. The 1:7 500 000 and the 1:1 000 000 scale data are the primary base frameworks used for all Atlas of Canada 6th Edition online maps. You can download Atlas of Canada data from this Web page on GeoGratis.

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