The Loma Mar 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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3.29 inches of rain fell in two days, the most for this week of the year since records began in 1906. The next wettest, 3.22 inches, fell in 1981.
Loma Mar’s center stands about 320 ft above sea level. Within three miles the land runs from 110 ft to 1,580 ft, a difference of 1,470 ft: steep hill country. The highest named summit within 15 miles is Mount Bielawski, about 3,280 ft, 12 miles east-southeast.
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 7×. 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, mudstone. Age: Oligocene to Pliocene, 2.6 to 34 million years old. About 8 mi of the line.
Sandstone, mudstone. Age: Miocene to Pleistocene, less than 23 million years old. About 6 mi of the line.
Mudstone, sandstone. Age: Paleocene to Oligocene, 23 to 66 million years old. About 2 mi of the line.
Greenstone. Age: Jurassic to Cretaceous, 66 to 202 million years old. About 0.7 mi of the line.
Sandstone, mudstone. Age: Jurassic to Cretaceous, 66 to 202 million years old. About 0.3 mi of the line.
Basalt. Age: Middle Miocene, 12 to 15 million years old. About 0.3 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 Loma Mar reaches the Pacific Ocean by way of Bloomquist Creek and Pescadero Creek: about 11 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Loma Mar; river miles along the main stem, rounded.
Loma Mar has a warm-summer Mediterranean climate. Summer afternoons average 81° in July; winter nights fall to about 40° in January. About 19 inches of rain fall in a normal year.
On November 14 Loma Mar normally reaches 65° and falls to 44°. The record high is 79°, in 2010; the record low 29°, in 1935. The most rain on this date, 1.72 in, fell in 1953.
Normals 1991–2020 and records since 1906 at Redwood City, 15 miles north-northeast, 290 ft lower. NOAA, through RCC-ACIS.
