This is an Earthcache – as such, there is no physical cache. Instead you will partake in a geology lesson by making observations and sending me the answers to 6 questions about St. Clement's Island. This island can only be reached by water taxi or personal boat. Written permission was given for this earthcache placement by the Maryland Department of Natural Resources - Point Lookout State Park Complex.

Tickets for the Water Taxi can be purchased inside St. Clement’s Island Museum. Water Taxi Season is from March 25 to October 31. The museum is open daily from 10 am until 5 pm, but The 2:00 p.m. departure from the museum is the last trip over to the island. The last trip back to the mainland from the island is 3:00 p.m. The taxi was $7 a person at publication of this cache, but visit this LINK because they may change. Please call the museum at 301-769-2222 before visiting to ensure water taxi operation and hours.

The island is open to all day use visitors sunrise to sunset, year round. Personal kayaks can be launched from Newtowne Neck State Park. It is approximately a long mile and a half mile paddle to St. Clements Island from Newtowne Neck State Park. The route is across the Potomac with strong currents, no shelter from wind, and some boat traffic.

St. Clements Island Earthcache was one of the five REQUIRED caches to find in 2023. CAM (Cache Across Maryland) is an annual event hosted by the Maryland Geocaching Society. Cache hiders are chosen by the MGS to place caches in various locations all over Maryland. 2023 was the 20th anniversary of CAM there was a cache placed in all 24 Maryland Counties as well as 3 in Baltimore City. It was held between March 25 and June 3 of that year.

THE PLYMOUTH ROCK OF MARYLAND

In 1634, 150 settlers via the Ark and the Dove on what became known as Blackistone Island (named after the family who lived here) and later St.Clement's Island (named for Pope St. Clement I, Patron Saint of Mariners) to found the 3rd English Colony in North America. The first two were Jamestown in Virginia and Plymouth in Massachusetts. The colony that was started here at St.Clement's Island is recognized as being the birthplace of Maryland.

Blackistone Lighthouse was built here in 1848, but was later decommissioned in 1932. Twenty-four years later a shell from the nearby Naval Proving Ground reportedly exploded near the abandoned lighthouse and set it afire. St. Clement's Island is Uninhabited today, but is a publicly owned historic preservation and home to St. Clement's Island State Park, where a replica lighthouse was built and 40 foot cross was erected in dediction to the first Marylanders and the beginnings of religious freedom.

A SHRINKING ISLAND

Maryland, like this island, is getting smaller. The sea level is rising 3-4 millimeters per year (12 to 16 inches per century). Beaches along the Maryland coast are eroding, its marshes are converting to open water, and its low lying land is gradually converting to marsh. Climate experts estimate that by the end of the next century, the sea level is likely to be rising 0 to 8 mm/yr(3 inches per decade). The majority of St. Clement's Island elevation is over 2 meters above sea level, while the northern point of the island is under about 1 meter above sea level.

St. Clement's Island is located in the Potomac River. This river is the second-largest tributary to the Chesapeake Bay and flows almost 400 miles from the mountains of West Virginia into the Chesapeake Bay. The average water flow of the river is 7 billion gallons a day. Shore erosion in the tidal Potomac River is mostly caused primarily by wind-driven waves and slope processes. Unlike ocean waves, which are largely created by wind, river waves are formed either by water flowing quickly downstream over a drop in elevation.

Storms, tides, winds, and rising seas are constantly creating and destroying islands and shorelines throughout the Chesapeake Bay region. St. Clement’s, like most Bay islands, is shrinking. Colonists on the Ark and the Dove surveyed the island in 1634 as being 400 acres. Today, approximately 40 acres remain.

As far back as the 1920s, the Federal Government used layers of large stones, called riprap, to control erosion near the Blackistone Island Lighthouse. Riprap, also known as rip rap, rip-rap, shot rock, rock armor or rubble, is rock or other material used to armor shorelines, streambeds, bridge abutments, pilings and other shoreline structures against scour and water or ice erosion

Modern rip rap is more than just rocks. Riprap is a permanent layer of large, angular stone, cobbles, or boulders typically used to armor, stabilize, and protect the soil surface against erosion and scour in areas of concentrated flow or wave energy. Riprap is typically placed along graded ditch, channel which prevents erosional undercutting. A filter fabric (geotextile) is placed behind the riprap, covered in crushed stone, which makes the erosion control more effective. The fabric allows the water to flow off the island and traps the soil normally lost in the run off.

In the 1970's through the efforts of the St. Mary's Historical Society and the State of Maryland, riprap was installed around the entire island. During that time the Maryland Park Service tried to slow the effects of erosion by allowing vegetation to grow and by limiting recreational use of the island.

In 2003 the island took a lot of damage from Hurricane Isabel. This storm surge not only produced higher than usual tides in along the Potomac River, it generated six foot waves that bombarded the coastline of Saint Mary's County. These taller waves eroded upland reaches that were not usually subject to wave attack, and these waves were also able to reach much further inland than normal. Here on St. Clements these raging waters toppled a wall of rip rap, as well as washing away a portion of the island's bank (see photos above).

A LIVING SHORELINE

Recovery came in 2015 when the U.S. Army Corps of Engineers developed plans to create a living shoreline along the southern point of the island. This plan included constructing a new rock sill over the footprint of existing rock revetment as well as constructing a new 30-foot wide rock spur by 100-foot long on the western side, and a new 26.5-foot wide by 71-foot long rock spur on the eastern side.

After the sill was completed they deposited approximately 132 cubic yards of sand to fill a 2,760 square foot area to create a sand planting terrace landward of the sill. This sand was then planted with Cordgrasses and wetland plantings, all to extend no more than 78 feet channel ward of the approximate mean high water shoreline.

A living shoreline is less expensive than rip rap, and it creates habitats. It uses a combination of planting native marsh plants to control sediments and a series of offshore rock structures to serve as a breakwater. They typically use a combination of plants, rocks, and sand to protect the shoreline. It is a natural system that slows down waves coming ashore, filters water coming in from the Potomac, as well as runoff flowing off of the island into the river. Filtering the sediment helps keep the waters of the Potomac and the Chesapeake Bay clear.

A sill is a rock structure placed parallel to the shore so that a marsh can be planted behind it. It has been used extensively in Chesapeake Bay due to the fact that these structures can be used in a wide range of habitats and energy levels. Sills create a natural buffer and preserve and create habitat for estuarine, shallow water, and intertidal organisms. The use of rocks in creating the sill is necessary to protect the created habitat from erosion. These sites may require ongoing maintenance, particularly after storm events.

Spurs are used as a transitional structure in order to minimize impacts of structures on adjacent properties. They can attach to an adjacent structure such as a groin to prevent flanking. They can be shore attached to help maintain the integrity of the shore protection system while seeking to minimize downdraft erosion.

LOGGING REQUIREMENTS:

To log this Earthcache: Read the geology lesson above. Answer all six questions posted below and post photo. Answers can be sent via e-mail or messenger contacts on my Geocaching profile. Group answers are fine, but do not post the answers to the questions in your logs.

QUESTION 1. Why is the state of Maryland invested in keeping St. Clement's Island from eroding away?

QUESTION 2. How much of the island has eroded away since the 1634 survey?

QUESTION 3. Why is having a living seashore more beneficial to armored rip rap?

QUESTION 4a. Using this TIDE CHART LINK was the tide high or low at the time of your visit?

QUESTION 4b. Examine the sill and planted sea grasses from one of the arches. Is the sill marsh submerged at the time of your visit?

QUESTION 5. Does the sill and spurs appear to be successful in diverting wave energy away from the island?

QUESTION 6. Do you think that Maryland will be able to keep successfully defending off erosion and save the island from vanishing away?

POST PHOTO IN YOUR LOG: Posting a photo in your log readily indicates that you (and anyone else logging the find) are at the location. You do not have to show your face, but the photo should be personalized by you or a personal item on St. Clément's Island. NOTE: Per newly published Earthcache guidelines, this requirement is REQUIRED to claim the find.

Awesnap has earned GSA's highest level:

REFERENCES

1. Blackistone Island (Replica) Lighthouse website, lighthousefriends.com
2. St. Clement's, Cradle of State Randi Henderson, The Baltimore Sun, December 21, 1997, Page B1, newspapers.com
3. Row Over St.Clements Robert Breen, The Baltimore Sun, June 21, 1962, Page 12, newspapers.com
4. Public Notice U.S. Army Corps of Engineers Baltimore District, PN 15-54, PDF, nab.usace.army.mil
5. St. Clements Island State Park Maryland Park Service, website, dnr.maryland.gov
6. Our State Cumberland News Times, March 24, 2020, newspaper, St. Clements Island State Park Maryland Park Service, website, newspaperarchive.com
7. Structural Living Shoreline Options Virginia Institute of Marine Science William & Mary, website, vims.edu
8. Governments Plan for Development of Land Vulnerable to Rising Sea Level: Maryland W.H.Nuckols & P.Johnson, Maryland". In The Likelihood of Shore Protection along the Atlantic Coast of the United States, 2010, Log Photo, risingsea.net
9. HURRICANE ISABEL AND SHORE EROSION CHESAPEAKE BAY, MARYLAND L.Hennessee & J.Halka, Maryland Geological Survey, 2004, Conference Poster, mgs.md.gov
9. Untitled Lighthouse Photo PathfinderMark, Ever changing Island, July 28, 2021, Log Photo, geocaching.com