Plate No. 1 · Atlanta and its Piedmont. Relief from Copernicus GLO-30; rivers from USGS NHD; the Eastern Continental Divide from the USGS Watershed Boundary Dataset; roads and city limits from Census TIGER 2024; rail from MARTA GTFS.
Sunny
Mostly sunny
Mostly sunny
Chance of showers
Storms likely
Showers likely
Chance of showers
As Helene passed two years ago this week, 11.12 inches of rain fell at the airport in 48 hours, the most in any two days since records began in 1878. The old mark, 9.59 inches, had stood since 1886.
Porter’s sunflower is gilding the granite on Stone Mountain and Arabia Mountain.
Fall warblers are moving over Kennesaw Mountain on north winds after each front.
Chimney swifts gather at dusk and spiral into chimneys before leaving for South America.
Muscadines are ripening on the vines along the river.
Atlanta sits on the Piedmont, the worn-down foothill country between the Blue Ridge and the Coastal Plain. Under the lawns and the kudzu lies hard crystalline rock, gneiss, schist and amphibolite, that was buried, heated and folded hundreds of millions of years ago as continents collided to raise the Appalachians.
In a warm, wet climate that rock rots in place. Feldspar weathers to clay and iron rusts, which is where the red clay every Atlanta gardener knows comes from. Beneath it lies saprolite, rock so decayed you can dig it with a shovel. Where the bedrock resisted, it stands up as domes and ridges: Stone Mountain, Arabia Mountain, Kennesaw Mountain.
The straightest line in the landscape is a fault. The Brevard Fault Zone runs northeast to southwest just northwest of the city, and the Chattahoochee follows its belt of sheared, weaker rock from Lake Lanier past Six Flags.
Schematic. Surface profile from 3-arc-second terrain; vertical exaggeration about 16×. Rock units generalized from the Georgia geologic map; production sections are drawn from the USGS State Geologic Map Compilation.
Light gray and fine-grained, quarried from the dome from the 1800s for paving, curbs and buildings.
Swirled gray “Lithonia granite” from east DeKalb, laid as curbstones across the South.
Indiana limestone outside, Georgia marble inside, under a dome gilded with gold from Dahlonega.
Two raindrops that land a few blocks apart downtown reach the sea about 250 miles apart.
Atlanta was put on high ground for the railroads, not beside a big river. The city drinks mostly from the Chattahoochee and Lake Lanier, one reason Georgia, Alabama and Florida have fought over the river’s water for decades.
The Flint River begins in culverts beneath the runways of Hartsfield–Jackson.
Cold water released from the bottom of Lake Lanier keeps the Chattahoochee cold enough for trout well into the northern suburbs.
48 miles of the river below Buford Dam are a national recreation area.
They call it the city in a forest, and it earns the name: nearly half of Atlanta is shaded by trees. Ravines too steep to build on hold oak, hickory, tulip poplar and beech, and Fernbank Forest keeps a stand of old-growth Piedmont woods inside the city. The granite domes to the east grow plants found almost nowhere else.
The tallest tree in the city’s ravines, with green-and-orange tulip flowers high in the canopy.
Atlanta’s classic street oak, with narrow, willow-like leaves.
A long-lived oak whose acorns feed deer, turkeys and blue jays.
The pine of old fields, and the yellow pollen that coats every car in spring.
White blooms in early April; glossy red fruit for the birds in fall.
Big evergreen leaves and lemon-scented flowers the size of dinner plates.
Smooth gray trunks in cool ravines such as Fernbank Forest; pale leaves hang on all winter.
Star-shaped leaves that turn wine red, and spiky gumballs underfoot.
The “yellow daisy” that gilds the granite outcrops each September.
A tiny red succulent that carpets rain pools on bare granite.
A fragrant pink native azalea of creek banks.
An invasive vine from East Asia that smothers woodland edges.
Georgia’s state bird, a rusty mimic singing from the shrubs.
Pours into chimneys at dusk before flying to South America.
A migrant that stops over on Kennesaw Mountain in spring and fall.
The loud hawk of wooded neighborhoods.
A tiny bird with a huge teakettle song.
Year-round red at every feeder.
Stalks the shoals of the Chattahoochee.
A crow-sized drummer of old trees and big parks.
Common even inside the Perimeter.
The fox that climbs trees.
Now settled across the whole metro.
Back on the Chattahoochee and its creeks.
Crosses yards and trails after summer rain.
The lizard on the porch rail, pink throat fan out.
The metro’s most common venomous snake: shy and well camouflaged.
Found only in the Chattahoochee and Flint basin, in rocky shoals.
Green months are when to look. Species drawn from research-grade iNaturalist and GBIF records inside the city limits and reviewed by hand; seasons from USA National Phenology Network and eBird frequency by week.
A strong El Niño is building. In past strong El Niño winters, Atlanta has leaned wetter and cooler than normal.
See every El Niño winter in Atlanta since 1950 →
Atlanta exists because of a surveyor’s stake. In 1837 the state railroad coming south from Chattanooga needed an end point, and it was driven on a ridge southeast of the Chattahoochee. The town that grew around it was called Terminus, then Marthasville, and from 1845, Atlanta.
Later lines came in along the ridge tops, which is why the old railroads and the Eastern Continental Divide trace much the same crooked path through town. The interstates followed the railroads, and the airport grew into the busiest passenger hub in the world.
69° → 62°, dry
69° → 65°, dry
69° → 62°, dry
69° → 66°, dry
69° → 65°, dry
69° → 64°, dry
From The System on forecast.city: NDFD 2.5 km forecast sampled every eight miles along the pavement.
