Question: Which county does Stone Mountain lead into, at its longest point?
About the article "Stone Mountain", section "Geology".

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Stone Mountain is a pluton, a type of igneous intrusion.
Primarily composed of quartz monzonite, the dome of Stone Mountain was formed during the formation of the Blue Ridge Mountains, part of the Appalachian Mountains.
It formed as a result of the upwelling of magma from within the Earth's crust.
This magma solidified to form granite within the crust five to ten miles below the surface.
Stone Mountain pluton continues underground at its longest point into Gwinnett County.
Numerous reference books and Georgia literature have dubbed Stone Mountain as “the largest exposed piece of granite in the world".
This misnomer is most likely a result of advertisement by granite companies and early park administration.
Stone Mountain, though often called a pink granite dome, actually ranges in composition from quartz monzonite to granite and granodiorite.
The minerals within the rock include quartz, plagioclase feldspar, microcline and muscovite, with smaller amounts of biotite and tourmaline.
The tourmaline is mostly black in color, and the majority of it exists as optically continuous skeletal crystals, but much larger, euhedral pegmatitic tourmaline crystals can also be found in the mountain's numerous, cross-cutting felsic dikes.
Embedded in the granite are xenoliths or pieces of foreign rocks entrained in the magma.
The granite intruded into the metamorphic rocks of the Piedmont region during the last stages of the Alleghenian Orogeny, which was the time when North America and North Africa collided.
Over time, erosion eventually exposed the present mountain of more resistant igneous rock.
This intrusion of granite also gave rise to Panola Mountain in DeKalb County, smaller outcroppings further east of Stone Mountain.
Hawksbill Mountain is a mountain with an elevation of .
Marking the border between Madison County and Page County in Virginia, the summit of Hawksbill Mountain is the highest point in Shenandoah National Park, as well as the highest point in both Madison and Page counties.
The north face of Hawksbill Peak is a drop into Timber Hollow, which is the largest elevation change in the park.
The summit is one of the few places in Shenandoah National Park where one can find balsam fir, a tree more typical of northern New England and southeast Canada.
Red spruce was once found near the summit but the last of the trees died out over 20 years ago.
The National Park Service has constructed a stone observation platform at the summit.
Byrd's Nest No.
2, one of a series of shelters built in the park by Senator Harry Byrd, is nearby.
Hawskbill peak is also the site of a Peregrine Falcon restoration project.
The summit of Hawksbill Mountain can be reached by a short hike from a trailhead located at the Upper Hawksbill parking area, just off of Skyline Drive in Shenandoah National Park.
A number of other hiking trails lead to the summit of Hawksbill, while the Appalachian Trail goes around and about in elevation below the summit. 
Sweat Mountain is a low mountain located in far northeastern Cobb County, Georgia, in the suburbs north of Atlanta.
The exact GNIS location of its summit is , and it has an official (USGS) elevation of above mean sea level.
It is the second-highest point in the county behind Kennesaw Mountain, and second in the core metro Atlanta area, behind Kennesaw Mountain, which is also in Cobb County.
It is fifth if the exurban counties further north are considered.
This height has made the mountain very attractive for radio, having several transmitters, radio towers, and antennas, for pagers, cellphones, broadcasting, and amateur radio.
The fact that Stone Mountain and Kennesaw Mountain are both protected as parks has led to a proliferation of technology at the top.
At the same time, both the antenna farm and the densely packed houses detract from the view of the mountain from surrounding areas of northeast Cobb, south-southeast Cherokee (including much of Woodstock), and western Roswell.
Sweat Mountain is also a part of the ridge that divides the Chattahoochee River basin to the south and southeast, from the Lake Allatoona (Etowah River) basin to the north and northwest.
From Sweat Mountain, this runs west-southwest through Cobb to Kennesaw Mountain and Lost Mountain. 
At , Mount Ord is part of the White Mountains, and is located in Apache County on the Fort Apache Indian Reservation.
Snow often stays on this mountain the longest during summer due to its high elevation and gentle north slope, snow can stick at , sometimes more, until June, only then melting into patches. 
According to the 2000 census, the county has a total area of , of which (or 98.73%) is land and (or 1.27%) is water.
The county is divided between two major basins.
Most runoff flows into the Chattahoochee River along the southeastern border, directly via Willeo Creek, Sope Creek (Sewell Creek), Rottenwood Creek (Powers Creek), and others.
The large Sweetwater Creek is the other major stream, carrying the waters of Noses Creek (Ward Creek, Olley Creek, and Mud Creek), Nickajack Creek, Powder Springs Creek (Rakestraw Creek, Mill Creek) and others into the Chattahoochee.
A ridge from Lost Mountain in the west, to Kennesaw Mountain in the north-central, to Sweat Mountain in the extreme northeast, divides the far north-northwest of the county into the Etowah River basin, which includes Lake Allatoona.
Noonday Creek (Little Noonday Creek) flows northward into the lake, as does Allatoona Creek, which forms a major arm of the lake.
Proctor Creek forms the much older Lake Acworth, which in turn empties directly into Lake Allatoona under the Lake Acworth Drive (Georgia 92) bridge.
There are several high points in Cobb County.
Sweat Mountain, in the extreme northeast portion, runs along the border with Cherokee County, and is the metro area's major antenna farm Blackjack Mountain, a low ridge between central and east Cobb Kennesaw Mountain: the highest point in the county and in the entire suburban area of metro Atlanta, located in the north-northwest between Kennesaw and Marietta Little Kennesaw Mountain: an offshoot of Kennesaw Lost Mountain, in western Cobb Pine Mountain, west-northwest of Kennesaw Mountain, between Kennesaw and Due West Brushy Mountain, near Kennesaw Mountain, just southeast of Barrett Parkway at Cobb Parkway Vinings Mountain or Mount Wilkinson, overlooks the town of Vinings