The Hilltop 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
Mostly cloudy; cooler
Partly cloudy
Mostly cloudy
Partly cloudy
Partly cloudy
26° on Nov. 14, 2018, the coldest reading for this week of the year since 1901. Next is 29° in 2008.
Hilltop’s center stands about 520 ft above sea level. Within three miles the land runs from 480 ft to 580 ft, a difference of 100 ft: gently rolling country.
Under the town center the state geologic map shows El Pico Clay (claystone), from the Middle Eocene, 38 to 48 million years old.
The section below crosses 5 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.
Sandstone, claystone. Age: Eocene, 34 to 56 million years old. About 12 mi of the line.
Sandstone. Age: Eocene, 34 to 56 million years old. About 6 mi of the line.
Claystone. Age: Middle Eocene, 38 to 48 million years old. About 3 mi of the line.
Claystone, sandstone. Age: Eocene, 34 to 56 million years old. About 2 mi of the line.
Fine-detrital, coarse-detrital. Age: Holocene, less than 12,000 years old. About 2 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 Hilltop reaches Corpus Christi Bay and the Gulf of America by way of Martin Branch, the Frio and the Nueces: about 200 river miles.
Lakes on the way: Horseshoe Tank and Lake Corpus Christi.
55 miles of the trip are on the Frio.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Hilltop; river miles along the main stem, rounded.
Hilltop has a hot semi-arid climate. Summer afternoons average 100° in August; winter nights fall to about 44° in January. About 22 inches of rain fall in a normal year.
On November 14 Hilltop normally reaches 76° and falls to 53°. The record high is 94°, in 1902; the record low 26°, in 2018. The most rain on this date, 1.11 in, fell in 1923.
Normals 1991–2020 and records since 1901 at Cotulla La Salle County Airport, 16 miles south. NOAA, through RCC-ACIS.
