Concord, 1897. USGS Historical Topographic Map Collection, via Esri.Concord, 1959. USGS Historical Topographic Map Collection, via Esri.San Francisco, 1978. USGS Historical Topographic Map Collection, via Esri.Walnut Creek, 1993. USGS Historical Topographic Map Collection, via Esri.Walnut Creek, 1995. USGS Historical Topographic Map Collection, via Esri.USGS National Map topo, today.
Your place in the living year
Martinez
Contra Costa County · California · 94553 37.9558, -122.0987
Twilight ends 6:46 pm dark 7:47 pm the skyline
Waxing Gibbous 96% lit
Rises 5:21 pm Peak 12:04 am Sets 6:47 am
Worth noticing
Nothing singled out today
What is happening here
0 observationsUnderstory is still assembling the picture for this place.
Flora of Contra Costa County
What grows here
Expected in bloom (mid autumn)
Source: USDA PLANTS. Bloom and fruit periods are USDA ranges, not live observations.The standing record
What this place is made of
Growing zone
9b
Zone 9b here corresponds to average annual extreme winter lows of 25–30°F.
Soil
Cut and fill land-Diablo complex, 9 to 30 percent slopes
Cut and fill land (fill part) is about 75% of this mapped soil unit · very slow infiltration and high runoff potential
Mapped geology
Mesozoic sedimentary rocks
Mesozoic · siltstone,sandstone,shale
Mapped by the Geological Survey of Canada, via MacrostratClimate and landscape
Mediterranean California
About 18.1 inches of precipitation per year
Lie of the land
A gentle slope facing southwest
200 feet above sea level · the ground falls about 4°
Over open ground the sun would shine 18 min longer on June 21, and 52 min longer on December 21: the hills take that much.
- Winter solstice: 8 h 40 min of direct sun over the terrain, of 9 h 32 min with a flat horizon · clears the skyline 7:35 am, behind it 4:15 pm
- Summer solstice: 14 h 30 min of direct sun over the terrain, of 14 h 48 min with a flat horizon · clears the skyline 5:49 am, behind it 8:19 pm
Habitat today
Mostly roads and buildings
- Within half a mile: 39% roads · 38% buildings and pavement · 18% street trees and planted ground · 4% introduced grasses and weeds
- Largest unbuilt ground: California Ruderal Grassland and Meadow (4%)
- Nearest mapped water and wetlands: stream or river, 0.4 miles southwest
Before settlement
California Central Valley and Southern Coastal Grassland
LANDFIRE's model of what this ground most likely supported before European settlement, from its soils, climate and historical fire. In that regime, fire returned about every 4 years.
- 77% California Central Valley and Southern Coastal Grassland
- 10% California Central Valley Mixed Oak Savanna
- 5% California Coastal Live Oak Woodland and Savanna
- 5% California Montane Riparian Systems
Watershed
Walnut Creek-Frontal Suisin Bay Estuaries
Subwatershed 180500010204 · Suisun Bay subbasin · California Region
USGS Watershed Boundary Dataset · NHDPlus, traced by USGS NLDIWater quality
Grayson Creek is impaired
- Grayson Creek: impaired for aquatic life, by harm to aquatic life of unknown cause and pesticides
- Not yet assessed: Alhambra Creek (Contra Costa County)
Scars and events
On record nearby: 14 landslides · a record flood
- 14 older landslides mapped within half a mile from the shape of the ground, undated
- Highest flow in 25 years of peaks at Walnut Creek at Concord, 2.8 miles east: 5 January 1982, 13,300 cubic feet per second
Old maps
Mapped since 1897
- Walnut Creek, 1:24,000: 1947, 1949, 1959, 1993, 1995
- Concord, 1:62,500: 1897, 1915, 1942, 1943, 1959
- San Francisco, 1:100,000: 1978
Open USGS TopoView here, and click the map to list every edition
USGS Historical Topographic Map Collection · each year opens that edition's scan, a large PDF