This Waymark Falls within Great Falls
National Park (Virginia), Entrace to the park is 5 dollars
per car including a 3 day pass.
A view of Mather Gorge from the south
Basic Geological Information:
Mathers Gorge is a gorge that runs along a fault line within the
Potomac River Gorge. The Potomac river gorge was created over the
course of 35 Thousand years of erosion. Because of the fault line
the erosion of mathers gorge is the straitest mile on the Potomac
River.
Technical Geological Information:
The Mather Gorge Formation, which dominates the area from Carderock
west, consists of interbedded quartzose schist and metagreywacke.
Drake interprets the schist and the metagreywacke as resulting from
the metamorphism of turbidites deposited while the Iapetus Ocean
covered the Potomac terrane. The highest grade of deformation
occurs near the Plummers Island Thrust Fault. Down river from Great
Falls to the main area of the fault, a significant number of
migmatic and phyllonitic fragments, products of the metamorphism of
granite and granodiorite, are present in the formation.
Although the Sykesville Formation is younger than the Mather Gorge
Formation, it was thrust underneath the Mather Gorge Formation.
Most of the Sykesville Formation, which makes up most of the
surface east of Carderock to Bannockburn, consists of
metasedimentary granofels with high concentrations of quartz and
feldspar. The rock resembles granite and granite gneiss, and was
known in the first half of the twentieth century as the Sykesville
Granite. In some areas, such as the area just east of Old Anglers
Inn and just south of Fawsett Farms and the area around
Congressional Manor, most of the upper section of the formation
consists of olistoliths of phyllonite from the Mather Gorge
Formation.
To Claim this cache you will need to
complete the 4 task below which will end up involving 3 or more
miles of hiking along the beautiful Mather Gorge!
To log this EarthCache:
1. What is the date at the bottom of the
plaque?
2. To what does he nearby sign describe about the gorge?
3. Since different Theories exist about the Gorge, what is yours
(in 2 sentences)?
4. Go to these coordinates N 38° 58.941 W 077° 14.670 (southern
end) and take a photo of you and your GPS with the Gorge in the
background.
While walking along the gorge enjoy the views and maybe you will
find the answer to it's creation!
Geology Map of the Great Falls region