The Rockland plate. Relief from Copernicus GLO-30; rivers and lakes from USGS NHD; watersheds from the USGS Watershed Boundary Dataset; roads and city limits from Census TIGER 2024.
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Rockland’s center stands about 1,180 ft above sea level. Within three miles the land runs from 660 ft to 1,330 ft, a difference of 670 ft: hilly country. The highest named summit within 15 miles is Adventure Mountain, about 1,480 ft, 5 miles east-northeast.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 23×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Basalt. Age: Mesoproterozoic, 1.1 to 1.1 billion years old. About 17 mi of the line.
Andesite, basalt. Age: Mesoproterozoic, 1.1 to 1.1 billion years old. About 5 mi of the line.
Sandstone. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 1 mi of the line.
Rhyolite. Age: Mesoproterozoic, 1.1 to 1.1 billion years old. About 0.9 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale.
Heights from Copernicus GLO-90 (a surface model: it includes buildings and tree canopy); summits from USGS GNIS; rivers from USGS NHDPlus HR; rock from the USGS State Geologic Map Compilation.
A raindrop that lands in Rockland reaches Lake Superior by way of the Ontonagon: about 20 river miles. From there it moves on through the Great Lakes, over Niagara Falls and down the St. Lawrence to the Atlantic.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Rockland; river miles along the main stem, rounded.
