How Do We Know Immigrants Came to the Hohokam Region?
After about A.D. 1275, distinctive, non-Hohokam artifacts and architecture began to appear at sites in the Hohokam region (Remember Puzzle Piece #1?). Archaeologists have long asked what this means.
- Do these artifacts signal trade between the Hohokam and groups in other regions?
- Were Hohokam groups copying what their neighbors were doing?
- Do these new artifacts and architecture indicate that immigrants entered the region?
To illustrate how archaeologists concluded that migration happened, we will walk through their reasoning process and focus on one piece of evidence: Maverick Mountain Series pottery.
The Maverick Mountain Series is a group of pottery types that look like ceramics made in the Kayenta region of northeastern Arizona and southeastern Utah. These distinctive types began to appear in central and southern Arizona beginning around A.D. 1275.
Was Maverick Mountain Series Pottery Traded To Hohokam Groups?
To answer this question, archaeologists had to determine where Maverick Mountain Series pottery found in the Hohokam region was made. This was accomplished through petrography, a scientific method used by geologists to identify and describe the minerals in rocks and sands.
Crushed rock or sand is often added to clay in the process of making pottery. This added material, called temper, makes the clay less sticky and prevents the pot from cracking when it dries and is fired. Because scientists can match the minerals in temper with minerals present in different rocks and sands, they can determine if a pot was made from locally available raw materials, or if it must have come from outside the region. Even if a pot looks like those made in northern Arizona, if its temper is sand from the Hohokam region, it was made in southern Arizona.
Researchers initially focused their petrographic study on the San Pedro Valley. Petrographers took samples of the different deposits of sand found in the valley and then determined which minerals were present and the abundance of each. When these researchers examined pieces of Maverick Mountain Series pottery found at archaeological sites in the San Pedro, they found that almost all of them had been made using sand from two specific places in the valley. They were made in southern Arizona, in the Hohokam region, not in the Kayenta region to the north. Petrographic analyses in other parts of the Hohokam region indicated the same result – Maverick Mountain Series pottery was being made locally in many places in central and southern Arizona.
Was Maverick Mountain Series Pottery Copied by Hohokam Groups, or Did Immigrants Make It?
Perhaps people living in the south took a trip north, saw some pottery, liked the designs, and decided to copy them. Or, maybe people from the north moved to the south, and brought their tradition of pottery making with them. The key to deciding between these two hypotheses is understanding how people learned to make pottery when they were young. Even when people copy a new decorative style, they typically use the same manufacturing technology they learned when they first made pottery.
Maverick Mountain Series pottery was made using the coil-and-scrape technique. Vessel walls were build up from thin, rope-like coils of clay which were then pinched together to form the walls. The walls were then scraped with a piece of gourd or broken pottery to thin and shape them. The same technology used to produce Maverick Mountain Series pottery is associated with the Kayenta Anasazi archaeological culture of northeastern Arizona and southeastern Utah.
In contrast, Hohokam pottery was made using the paddle-and-anvil technique. The potter held a stone anvil inside the vessel and beat the vessel wall with a wooden paddle in order to build and form it into the desired shape.
Petrography shows that Maverick Mountain Series pottery was made in southern Arizona, not traded in from the north. The pottery is locally made, but with a foreign technology, which indicates the presence of people from the north, rather than copying. If these pots had been made by southern potters to look like northern pottery, they would have been constructed using the paddle-and-anvil technique common in the Hohokam region.
Are There Other Traces of Immigrants in Hohokam Sites?
Sites that have yielded Maverick Mountain Series pottery have produced other evidence of immigrants. One important marker is perforated plates. Perforated plates are ceramic vessels, made using the coil-and-scrape technique, with holes punched through their rims before they were fired. They first appeared in northern Arizona, around A.D. 500.
They were used in the Kayenta region as base-molds and potters’ turntables in coil-and-scrape pottery making. Like Maverick Mountain Series pottery, petrographic analysis has shown that perforated plates were made locally, in southern Arizona, after A.D. 1275.