Archaeology is a fantastic field because of all of the interesting methodologies that we can use to reconstruct the past. For example, archaeologists use satellite imagery to see buried walls, radar to detect sunken tombs, and X-rays to reveal where ancient pottery makers obtained their clay. Similarly, we at HARP are using modern technology to tell us more about prehistoric Peru.
Micromorphology is the study of sediments with the use of a petrographic, or polarizing light microscope. The technique was first developed in the soil sciences in the 1930s and is now widely used in archaeology throughout the globe. Micromorphology has allowed researchers to reconstruct the natural and human processes responsible for the formation of archaeological sites. With the help of Dr. Paul Goldberg (Boston University), we’re using micromorphology to understand the construction activities that built the temples at Huaricanga and to learn more about the types of activities that took place on the floors that were ritually cleaned (and thus left no traces visible to the naked eye).
The process of taking a micromorphology sample is simple in principle, but sometimes difficult in practice.
- Choose an appropriate place to sample. Often large profiles are sampled to obtain a series of floors, burning events, construction fills, etc. We targeted an area in the middle of the room that has a series of superimposed floors with fills in between them.
- Remove a block of sediment that measures approximately 8 cm x 10 cm x 12 cm.A column of sediment is essentially pedestaled for sampling. In our case we cut an area that was a bit wider to allow us to pass the wrappings around the block. Since the floors are plastered and thus hard, we used a sharpened trowel as a chisel and hammered down through the different levels.
- Wrap the sediment block tightly. We used plaster bandages like those used to support broken limbs. Although the plaster dust was a bit messy, the plaster ensures that the loosest sediments stay intact. An intact sample ensures a better block to read the microstratigraphy. Alternatives to plaster bandages include toilet paper and packing tape as well as metal boxes used to cut out blocks. In the end, the sample looks a lot like a block of fresh cheese!
- Once dry, the sample is exported to the United States where it is impregnated with resin, cut into microscopic thin sections, and analyzed under a microscope.
The results from this analysis will provide another line of evidence to reconstruct the 5,000-year-old rituals that took place at Huaricanga…Stay tuned!