The Summit 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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23° on Nov. 13, 2019, the coldest reading for this week of the year since 1948. Next is 25° in 1963.
Summit’s center stands about 460 ft above sea level. Within three miles the land runs from 380 ft to 500 ft, a difference of 120 ft: gently rolling country.
Under the town center the state geologic map shows Citronelle formation (sand, gravel), from the Pliocene to Pleistocene, less than 5.3 million years old.
The section below crosses 2 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sand, gravel. Age: Pliocene to Pleistocene, less than 5.3 million years old. About 21 mi of the line.
Clay, sand. Age: Miocene, 5.3 to 23 million years old. About 3 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 Summit reaches Lake Pontchartrain and the Gulf of America by way of Clear Creek, the Bogue Chitto and the West Pearl: about 150 river miles.
110 miles of the trip are on the Bogue Chitto.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Summit; river miles along the main stem, rounded.
Summit has a humid subtropical climate. Summer afternoons average 91° in July; winter nights fall to about 38° in January. About 61 inches of rain fall in a normal year.
On November 14 Summit normally reaches 69° and falls to 45°. The record high is 85°, in 1993; the record low 25°, in 1963. The most rain on this date, 3.02 in, fell in 1993.
Normals 1991–2020 and records since 1948 at Mccomb Airport, 7 miles south. NOAA, through RCC-ACIS.
