The Islesboro 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.
Mostly cloudy
Partly cloudy; warmer
Partly cloudy
Mostly sunny
Mostly sunny
Mostly sunny
Mostly sunny
70° on Nov. 11, 2020, the hottest reading for this week of the year since 1976. Next is 68° in 2022.
Islesboro’s center stands about 30 ft above sea level. Within three miles the land runs from 0 ft to 200 ft, a difference of 200 ft: rolling country. Open water lies within three miles. The highest named summit within 15 miles is Mount Megunticook, about 1,370 ft, 9 miles west-southwest.
The section below crosses 6 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 29×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Slate, schist, quartzite. Age: Middle Ordovician to Late Ordovician, 450 to 470 million years old. About 8 mi of the line.
Felsic-volcanic, mafic-volcanic. Age: Middle Cambrian, 499 to 507 million years old. About 1 mi of the line.
Granite. Age: Devonian, 359 to 422 million years old. About 0.8 mi of the line.
Mudstone, sandstone, siltstone. Age: Neoproterozoic, 542 to 1,000 million years old. About 0.7 mi of the line.
Schist. Age: Silurian, 422 to 445 million years old. About 0.7 mi of the line.
Limestone, dolostone. Age: Neoproterozoic, 542 to 1,000 million years old. About 0.5 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.
Rain that falls on Islesboro runs straight into the Atlantic Ocean.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Islesboro; river miles along the main stem, rounded.
Islesboro has a warm-summer humid continental climate. Summer afternoons average 77° in July; winter nights fall to about 12° in January. A normal year brings about 69 inches of snow; with the rain, that comes to about 56 inches of water.
On November 14 Islesboro normally reaches 47° and falls to 32°. The record high is 65°, in 2010; the record low 8°, in 1986. The most rain on this date, 1.47 in, fell in 2018.
Normals 1991–2020 and records since 1976 at West Rockport 1 NNW, 14 miles southwest, 330 ft higher. NOAA, through RCC-ACIS.
