Written by Christina A. Conlee, author of Beyond the Nasca Lines: Ancient Life at La Tiza in the Peruvian Desert
“How do you know where to dig?”
This is the most common question people ask me when they find out I am an archaeologist. People often think archaeological work is very mysterious. In reality, archaeologists use many established methods, new technologies, and analyze an array of data to determine where to dig. The project I directed at the site of La Tiza in Nasca, Peru started with a research question, and like most archaeological projects, it built on previous work.
My earlier research revealed a period of time around AD 1000 when much of Nasca was abandoned. People did not return in significant numbers until at least AD 1200. I wanted to explore what caused this collapse and why society looked so different when the region was repopulated. In the post-collapse period large ceremonial sites with pyramids and plazas were no longer used, artifacts were less finely made, and warfare and conflict were more prevalent. To answer the question of why this dramatic change occurred, I needed to excavate a site that spanned this particular time period.
How do you find an appropriate site? Surveying is often the first step of a project. Modern technology can help tremendously in this step. Satellite imagery, high-resolution imagery taken by drones, and techniques such as LiDAR (which can see through forest canopies) can locate and map sites not easily visible from the ground. Geophysical techniques such as magnetometer and ground penetrating radar can identify underground architecture and other features.
In my case the region had been surveyed previously by Katharina Schreiber, who located and recorded hundreds of sites in the area. She did this via a “pedestrian survey”—walking over the region and finding sites—and with the help of photos taken by air. I looked through Schreiber’s site records to find ones that dated to the time of Nasca’s abandonment. Once I identified several sites that met my criteria I went to Nasca to visit the settlements.
The Nasca region is part of the northern reaches of the Atacama Desert, one of the driest places on earth. Here, the preservation of archaeological sites and materials is excellent. Since architecture and artifacts are still preserved on the surface, sites are easily visible on the ground. However, this visibility has led to an extreme amount of looting. The destruction of sites by looting makes it hard to analyze surface remains because materials from different time periods are often mixed together.
The Nasca region is part of the northern reaches of the Atacama Desert, one of the driest places on earth. Here, the preservation of archaeological sites and materials is excellent.
All places and environments have their particular challenges, and not all sites can be identified by surface remains. Finding and recording sites in a tropical rainforest, for example, would be very different than in the desert. However, archaeologists everywhere use similar methods to identify sites and create strategies for excavation. I chose La Tiza as my site because it had many intact areas despite the looting, and because it was the largest site that spanned the time period I wanted to study. La Tiza began as a small settlement where hunters and gathers lived for part of the year. Over time it grew into a large permanent town where farmers lived, and was a place where people were buried, and where religious ceremonies took place.
The question of where to dig then moves to the site level. Archaeologists can usually only excavate a small portion of large settlements, so they develop sampling strategies. I used the visible architecture and artifacts on the surface at La Tiza to sample portions that dated from different time periods. Once I established the time period and nature of certain areas, I conducted larger excavations in targeted areas.
However, what is on the surface is not always the best indication of what is below. Given the surface remains, I thought at first that La Tiza was primarily occupied from about AD 1200–1500; but it turned out that the site contained remains from as early as 3600 BC. My project was initially focused on domestic areas, but after I discovered two intact burials during the first year of excavations I changed the scope to include mortuary and ritual areas. Overall, I expanded the project to examine all time periods and the long-term changes that took place in the region. What started out as a three-year project focused on the nature of society in one time period turned into a multiyear project encompassing almost 5,000 years of human use of the site.
My research at La Tiza shows that you can never completely predict and control what you find. This element of surprise is one of the main things that make archaeology fun and exciting—and sometimes also frustrating. But although many aspects of archaeological research can be unpredictable and mysterious, and what you find might lead you into centuries and conclusions you hadn’t expected, deciding where to dig is the first and often the simplest step.