MD C&O Canal Section 2: Crossing the Fall Line, 6 mi.

We climbed out of my sister's air conditioned car at the Carderock parking area where we'd left off a few weeks ago. We were about to continue our walk on the C&O Canal yet the first thing I noticed was the wall of humidity that nearly knocked me over as I exited the car. The second thing was the sound of the Potomac. The C&O Canal follows the river closely for the five miles to Great Falls. It crosses the Fall Line through Mather Gorge, our destination. We figured the heat and humidity would affect our hiking plans and I'm glad we made some changes to our plans.

Canal and towpath elevated high above the Potomac.

Taken on the section we walked today - C. 1910, Library of Congress.

Hurry through the sunny patches and take your time in the shade!

The Fall Line runs from Trenton, New Jersey, to Richmond, Virginia, and along it are Wilmington, Baltimore, and Washington, D.C. This geophysical barrier prevented early explorers from sailing up most of the Mid-Atlantic's rivers. The drop in elevation from highlands to coastal plain, however, made perfect sense for erecting water-powered mills and industrial complexes and cities grew up around the hydro-power that came with the Fall Line. The building of the C&O Canal faced its greatest challenge here as engineers had to develop ways to lift and lower boats 75 feet in elevation.

Packet Boat on elevated canal over the Monocacy River. Courtesy NPS.

Freighter on the  re-watered ancient river channel. Courtesy NPS.

Disused packet boat in the de-watered, storm-damaged canal at Great Falls.

As engineers built all types of walls, dams, locks, and levies to make the lift up and over (or down and around) the gorge possible in the 1800s, they quickly learned that they had very little control of over the river. In high water and floods, disused river channels became torrents. Retaining walls and flood control measures leaked or failed. The abandoned and repurposed river channel at Widewater was difficult to keep watered when flood waters over-topped the canal caused multiple breaches across earthen towpath berms. It still gives the National Park Service troubles. The once-popular canal boat used for mule-pulled rides now sits high and dry in a unwatered section of canal that drained years ago during a hurricane-powered flood.

Widewater, an ancient river channel. 

Painted Turtles covered in Duckweed.

Blue Gill nests with males on guard!

Coming to Mather Gorge on the towpath. 

The Potomac flowed across this wide valley more than 2 million years ago but was slower and meandered around island outcrops of resistant metasedimentary rock. There were several major river channels and the river spread out across the hilly landscape for almost a mile. As ocean levels dropped when ice began forming during the Pleistocene Ice Ages, the water moved much more quickly carving deeper cuts and ravines through the bedrock. By 35,000 years ago - in the blink of a geologist's eye - the Potomac was actively down-cutting the Mather Gorge, abandoning ancient river terraces above and creating the dramatic scenes we see today.

Dry river channel abandoned 35,000 years ago.

Down-cutting revealed fault lines.

The Billy Goat Trail branches off the towpath in a few places in sections marked A, B, and C. Dogs were not allowed, but Amos was really feeling the heat so we decided to come back another day for that trail without him. We did take turns shade-sitting him so we could venture out on the boardwalk path to Olmsted Island. It was breathtakingly beautiful.

Side channel in the Mather Gorge on the walk to Olmsted Island. 

Chutes and slides!

Drops and ledges!

Great Falls at Mather Gorge.

At several points along the Olmsted Island path you can stop to observe examples of  River Bedrock Terrace with it's stunted trees and grassland-like pockets of wet and dry plant communities. I wished I'd taken longer to observe for butterflies and birds but the heat drove me quickly back to the shady spot where my sister and Amos waited. We both agreed that a trip back in the fall with leaves turning and avian fall migrants streaming south from Canada might be a better bet.

River Bedrock Terrace - a unique and perilous habitat.

The enormity of the engineering problems required workers to build multiple lift-locks to raise sections of the canal. The rock is hard, ancient sea bottom, metamorphosed into welded and warped layers of metagreywacke shot through with quartz veins that attest to its proximity to volcanic islands. This shelf of molten, submerged rock was moving westward on a continental conveyor bringing together tectonic plates that closed the ancient Iapetus Ocean. Canal builders who worked these canyons and ravines during the 1800s had no idea about crustal movements or the deep forces that cause continents to move.  What they did know was how to blast it, shape and stack it, and move it using winched derricks and block & tackle. With sledge-hammered drills and black powder they carved out locks, built walls, and shored up the towpath.

Blasting holes

What is not as apparent to the walker or biker along this stretch is the herculean effort required to restore the canal in the 1960s and to keep it in good shape today - an ongoing and costly maintenance plan that requires intimate knowledge of old engineering techniques combined with modern safe-guarding. The Great Falls area is a showpiece of historic preservation, but we both agreed that any big storm or flooding event has got to cause every NPS site manager and park engineer great concern. The roar of the river is a constant reminder that at high levels the Potomac here is destructive and deadly.

Rope grooves at Lock 15

Though the coming of coal-carrying railroads were the main economic cause of the C&O Canal's demise, the physical end of the canal and all of its historic assets may one day be due to increasingly severe and long-lasting flood events. On average, floods damage parts of the canal somewhere along its 184 mile length to Cumberland every ten years, but managers of this and other Chesapeake Watershed river parks say that these storms are packing a more damaging punch with amplified volume over longer periods. Hurricanes and slow moving "rain train" storm systems that pull warm water from the Gulf of Mexico and dump it into the Mid-Atlantic region carry more water than ever.

Lock, dam, and spillway at head of Widewaters.

Flooding is part of the natural cycle of river environments, but the human-built infrastructure of historic towns, canals, and parkland along them is at great risk to damage caused by climate change. I emailed a friend who manages a Potomac River park upstream. She wrote back "We hold our breath and pray this one or the next doesn't break the bank for our repair budgets that seem to include less and less funding for upkeep each year." (Name withheld at manager's request)

Great Falls Lockhouse and Tavern 

We walked two days - slowly and with many breaks - just over 8 miles total. We had envisioned doing ten-mile day walks by spotting cars for each day's section. The heat however was brutal and it didn't make sense to push ourselves over distances we weren't sure were good for us and especially for Amos. Black dogs do not do Mid-Atlantic summers well at all.  So, we just out-and-backed both days, north from Carderock one day and south from Great Falls the next.

Our section for this trip - Carderock to Great Falls. 

Amos has had enough!

Amos defiantly let us know when he'd had enough both days by laying down in the path many times on the way back to the car. I was starting to worry I'd have to carry an 80 pound dog. At Great Falls we encountered an older woman in the midst of heat stress and offered to help. I emptied Amos' cold water bottle into her tiny squishy 10 oz. plastic bottle. Unable to walk very far before having to sit back down on the side of the towpath, she was pale, shaking, and weak.  I added a some Powerade to her bottle and she quickly drank it down. Her family and some passersby were able to help her get her car about a half-mile away. To a heat stressed person, however, that half-mile must have seemed like ten miles. It's no joke! We hope she is now recovered and doing well. We're glad we made the decisions we did to shorten our hikes and limit our exposure to this brutal heat and humidity. Amos is very happy about that and has now enjoyed a coonhound spa day with a cool bath, paw butter massage, and lounging on the sofa in the AC. Hurrah!


Notes:

An NPS excellent online resource, "The Workers Who Built the C&O Canal" sheds light on canal culture of immigrant workers and the every day life in workers camps along the way. Workers Who Built the C&O Canal


Singin' down the C&O by Eric Brace and Peter Cooper -