The Ovilla 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.
Chance of showers
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20° on Nov. 12, 2019, the coldest reading for this week of the year since 1940. Next is 22° in 2014.
Ovilla’s center stands about 630 ft above sea level. Within three miles the land runs from 570 ft to 780 ft, a difference of 210 ft: rolling country. The highest named summit within 15 miles is Inspiration Point, about 870 ft, 7 miles west-northwest.
Under the town center the state geologic map shows Austin Chalk (marlstone, chalk), from the Late Cretaceous, 66 to 100 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 45×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Marlstone, chalk. Age: Late Cretaceous, 66 to 100 million years old. About 14 mi of the line.
Claystone. Age: Late Cretaceous, 66 to 72 million years old. About 5 mi of the line.
Black-shale, siltstone. Age: Late Cretaceous, 66 to 100 million years old. About 2 mi of the line.
Sand. Age: Pleistocene to Holocene, less than 2.6 million years old. About 1 mi of the line.
Fine-detrital, coarse-detrital. Age: Holocene, less than 12,000 years old. About 0.4 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 Ovilla reaches Galveston Bay and the Gulf of America by way of Red Oak Creek and the Trinity: about 440 river miles.
Lake on the way: Woodlands Golf Course Lake.
220 miles of the trip are on the Trinity.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Ovilla; river miles along the main stem, rounded.
Ovilla has a humid subtropical climate. Summer afternoons average 97° in August; winter nights fall to about 36° in January. About 41 inches of rain fall in a normal year.
On November 14 Ovilla normally reaches 68° and falls to 45°. The record high is 89°, in 1989; the record low 25°, in 2018. The most rain on this date, 1.32 in, fell in 1994.
Normals 1991–2020 and records since 1940 at Ferris, 13 miles east, 160 ft lower. NOAA, through RCC-ACIS.
