Welcome to a remote part of southwest New Hampshire -- a great snowmobiling road in the winter, and a country jaunt in the summer! This is a historical location - owned and operated by the Seventh-day Adventist denomination, but permission has been granted to view the rock walls for this earthcache. The area is most likely to have other visitors (muggles) on Saturday mornings, or when youth groups camp at the adjoining campground.
Geology:
Sullivan County Geology is mostly about volcanics -- specifically granite of several different varieties, Granodiorite, and of course the meamorphic rocks underlying the top layers and eratics brought in with the glacier. Whereas NH is known as the "Granite State," only 25% of the state is made up of granite, but over 36% of this region is granite! Most of the rocks are a combination of white and black, so you'll have to be more observant to determine which ones you're observing!
Granodiorite look similarto granite but are darker because they are plagioclase feldspar unlike granite. Bethlehem Graniodirite makes up 1/3 of ther ock in Sullivan County.
Schists - the medium grained minerals are laid flat, and its easy to see that they could “flake off” or be split in planes. Mica is a shiny flake in the local schist. the group here is called "Littleton Schist" and is a metamorphic result of both sedimentary and volcanic rocks -- and sometimes contains fossils!
Granite - usually harder than schists, and have even sized grains of several minerals. There is a lot of quartz in Granite in this area.
Gneiss - a metamorphic rock with a banded or foliated structure, typically coarse-grained. often looks like layers of rock "partially stirred" or "wrinkled".
Quartzite - appears in granite, but also alone in milky white or crystaline structure.
During the Pleistocene ice ages, glacial ice scoured and reworked the preexisting landscape of New England. At the last glacial maximum, the Wisconsi glacier covered this area -- it brought the Laurentide Ice Sheet to the region, covering up previous glacial events and debris, and shaping the land all the way to the islands off of Cape Cod, well south of this location. This even also was responsible for depositing vast amounts of glacial sediments atop much older bedrock units. The result is the unique variety of rocks you see!
Needless to say, the moraines (piles of rocks left behind by the glacier) are everywhere, some on the surface and others slightly under the soil layers. These rocks have been plowed up and stacked by area farmers for hundreds of years -- to create fields for planting and for livestock (and for houses, cemeteries, etc.) The result is a lot of rocks that need placed somewhere AND be useful at the same time...tah dah - rock walls!
Types of Walls
Thrown Wall -- This is the most basic type of stone wall. It lacks a formal structure or foundation. The walls don't take formal experience to build. They have rounded rocks in a wide variety of sizes assembled in walls. These are by far the most common type of stone wall in New England. Often bigger stones will be on the bottom and other sizes will fill the gaps as the wall height changes. The stones are not mined but rather come from the fields they surround. These walls often need repair and rebuilding so as to keep the animals inside the enclosure, but can be rebuilt easily without hiring a professional.
Laid Wall - At the beginning of the 20th century, an influx of settlers from Europe brough experienced quarrymen and masons to the area with new solutions for the farmers of New England. Soon, more formal walls of uarried or "dressed" stone appeared in the region. The rocks therefore are block shaped, often similar sized, and have a formal structure with fewer gaps inbetween stones. They more securely keep animals, don't fall down and need repair as easily, and also have a more elegant and formal look.
Rubble Filled Wall - Although a vast improvement, laid walls are not built to allow for the movement of soil beneath their foundations, movement that results from the freezing and thawing of water in the ground. Consequently, Rubble FIlled Walls have been developed. It combined the favoriable aspects of both the rubble and laid wall types. These walls consist of two laid walls built alongside each other, with a rubble fill placed between to add greater felexibility. The outer laid walls hold the wall together, while the rubble fill in the center allows the wall to settle and adjust to the changing forces acting beneath it (freeze and thaw).
Morter?
In modern times, morter has become part of wall building, especially in Laid Walls. Those walls that contain morter are called "Wet walls" walls, whereas those walls composed entirely of stone (no morter) are called "Dry walls." Morter makes a wall look much more formal, but loses significant flexibility and thus can degrade much more easily than Dry Walls.
Wall History
These walls have been repaired over the years. The original walls predate documentation, but since the property has been in continuous control by the same group since the mid-1800s, it hasn't changed much. The cemetery is one of the oldest in the region and holds several prominent members of the Christian Congregation who once worshipped in the nearby church. In fact, this building was the first Seventh-day Adventist Church, and the original members of that denomination are buried inside this stone wall.
Logging Requirements
Go to the coordinates and walk the length of the stone wall that runs parallel to the street
Identify--
A) which type or typesof of walls surround the cemetery and
B) Whether it is wet or dry
C) Identify any of the following rock identifiers present in the wall at the GZ (terms above) Are the rocks granite, schist, gabbro? Do you see amphiboles, or mica?
D) Does the size of rock or type of rock seem to vary/matter in the success of the wall 50-100 years after its placement?
Permission granted by Ken Brummel, site manager
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Links about the rock walls, the site, and geology of the area:
Geologic Unit of Sullivan County, NH - Link here
Granite and Granodiorite - link here
Stone walls of New England, NPS "Stone Walls" - Link Here