Welcome to Brown's Hill!
Welcome to Brown's Hill! This point is historically significant, as it is the last spot of the Mason-Dixon line personally surveyed by Charles Mason and Jeremiah Dixon, on October 11, 1767. The stone that currently marks this spot was placed by Cephas Sinclair in 1883 in the exact spot of Mason and Dixon's final marker.
What is Sandstone?
Sandstone forms over time when sand-sized particles, which are the result of the weathering and breaking down of larger rocks like granite or basalt, are transported by wind, water, or ice to places like beaches, deserts, or riverbeds. As these particles pile up in layers, the weight of the overlying sand presses down on the layers below, compacting them. Meanwhile, water moving through the sand deposits carries minerals like quartz, calcite, or iron oxide, which act as a sort of natural glue, cementing the grains together. Over millions of years, this process of compaction and cementation turns the loose sand into solid rock—sandstone.
What is Weathering?
Weathering is the natural process that breaks down rocks into smaller pieces or changes their composition over time, largely due to exposure to the elements. It happens in two main ways: mechanical (physical) weathering and chemical weathering. Mechanical weathering occurs when physical forces, like temperature changes, freeze-thaw cycles, or even plant roots, break rocks apart without altering their chemical makeup. For example, when water seeps into cracks in rocks and freezes, it expands, exerting pressure that can cause the rock to crack and break apart—a process known as frost wedging. Another example is abrasion, where wind-blown sand or rocks carried by rivers wear down rock surfaces over time, effectively grinding them into smaller particles. Biological weathering also plays a role, like when tree roots grow into rock cracks, exerting pressure that can cause the rock to fracture and break apart. Another example of biological weathering includes lichens and mosses that produce acids that can eat away at the rock.
Chemical weathering, on the other hand, occurs when chemical reactions change the minerals in the rock. For instance, when rainwater, which is slightly acidic due to dissolved carbon dioxide, reacts with minerals in rocks like feldspar, it can transform them into clay minerals through a process known as hydrolysis. In areas where rocks contain iron, oxidation (similar to rusting) can occur, turning iron-rich minerals into red or yellow-colored rust. Another example of chemical weathering is dissolution, where rocks like limestone or marble are slowly dissolved by acidic rainwater, causing them to wear away. This is why you often find large, eroded features like caves or sinkholes in regions with limestone bedrock. Over time, both mechanical and chemical weathering contribute to the gradual breakdown of rocks, producing smaller particles like sand, clay, or even dissolved ions, which are carried away by wind, water, or ice to form new landscapes.
EARTHCACHE LOGGING REQUIREMENTS
Please submit your answers to the tasks below within seven days of your online log.
0) What is the name and GC Code of the Earthcache you are submitting answers for?
1) Describe the appearance of the Boundary Stone. What would you describe the texture and color as?
2) Observe the marker for any signs of weathering. Using the information above and your observations, what type (or types) of weathering can be observed happening to the Boundary Stone?
3) Closely examine each side of the Boundary Stone. Is there one side that shows more signs if weathering compared to the others?
4) Given that this Boundary Stone is nearly 200 years old, how resistant to weathering do you think sandstone is?
5) REQUIRED - Please take a photo of you (or a personal item) with the Boundary Stone clearly visible in the background from GZ. Please try to frame your photo as to not reveal answers to the above questions.