Week 1: Part 3
While one team worked on learning the art of mapping with the Total Station surveying equipment, the other learned another art, that of laying out and prepping an excavation area.
First things first, the area of interest must be identified. For our purposes, a sloped area roughly 50 meters long and 20 meters wide was chosen for the fact that according to historic photos, this is the location of the stamp mill batteries and washing equipment (washing equipment being the technologies used in separating crushed rock from copper using water and gravity). The photo at right gives a pretty clear indication of the slope-gravity is definitely at work here.
Once your area of interest has been chosen, the size and orientation of your excavation areas- be they units, trenches, or shovel test pits- is decided upon. My interest in the mill is how the process of separation was carried out. Therefore, I decided to cover a very wide area that would run the length of the historic buildings while not over reaching in terms of scale. One long trench (2 meters wide and was laid out running lengthwise down the slope for about 40+ meters. Then starting from the top (where everyone is sitting in the photo) the trench was divided into 4 meter long excavation unit trenches. The way it shakes out is that two of these 2×4 meter units cover the stamp room (where the crushing occurred) and the others the washing room (where the separation with water/gravity occurred).
So how does one accurately create a 2×40+ meter trench and then divide it further into smaller 4 meter sections while also maintaining a parallel course with the buildings original orientation? Line of sight, long tape measures and the Pythagorean theorem that states A squared + B squared = C squared.
First, a known outer foundation wall was identified. From here, a parallel line could be created by line of sight. From here, another line could be run perpendicular to the first, creating our first point. Now two sides exist but are not necessarily square to each other. By using the Pythagorean theorem, the students were able to accurately create a right triangle, making sure those two sides were square to each other and providing a second starting point to run another parallel line exactly 2 meters from the first. Then repeating this process on a smaller scale, each 4 meter long section could be created.
String was run around the corners to delineate each 2×4 meter trench. Once these are “laid out,” they needed to be recorded both by photograph and drawing before excavation could begin.