The Delta 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.
Partly cloudy
Partly cloudy; warmer
Mostly sunny
Sunny
Partly cloudy
Mostly sunny
Mostly sunny
78° on Nov. 12, 1999, the hottest reading for this week of the year since 1936. Next is 77° in 1993.
Delta’s center stands about 460 ft above sea level. Within three miles the land runs from 300 ft to 720 ft, a difference of 420 ft: hilly country. The highest named summit within 15 miles is Red Hill, about 690 ft, 13 miles north.
The section below crosses 10 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 24×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Schist, phyllite. Age: Paleozoic, 252 to 542 million years old. About 7 mi of the line.
Mica-schist, quartzite. Age: Paleozoic, 252 to 542 million years old. About 5 mi of the line.
Biotite-schist. Age: Proterozoic, 542 to 2,500 million years old. About 4 mi of the line.
Metagraywacke, muscovite-schist. Age: Proterozoic, 542 to 2,500 million years old. About 3 mi of the line.
Slate. Age: Ordovician, 445 to 487 million years old. About 2 mi of the line.
Serpentinite. Age: Proterozoic to Paleozoic, 252 to 2,500 million years old. About 1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 4 smaller units along the line are not listed.
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 Delta reaches Chesapeake Bay and the Atlantic Ocean by way of Scott Creek, Muddy Creek and the Susquehanna: about 30 river miles.
Lake on the way: Lake Aldred.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Delta; river miles along the main stem, rounded.
Delta has a humid subtropical climate. Summer afternoons average 88° in July; winter nights fall to about 25° in January. About 48 inches of rain fall in a normal year.
On November 14 Delta normally reaches 56° and falls to 37°. The record high is 75°, in 1955; the record low 22°, in 2019. The most rain on this date, 1.02 in, fell in 1957.
Normals 1991–2020 and records since 1936 at Conowingo Dam, 9 miles east-southeast, 420 ft lower. NOAA, through RCC-ACIS.
