Casa Grande Ruins National Monument

Casa Grande Ruins National Monument

Just For Kids

Casa Grande Ruins, Just For Kids

Be A Junior Ranger

Discover the history of Casa Grande Ruins, the proud and hard-working people living here in ancient times, and how they managed to flourish in such a harsh environment! Kids of all ages will enjoy the activities, games, and puzzles designed to learn about the this very special place. Activities can include visiting the Big House, attending a ranger-led program, visiting the ball court, studying the museum exhibits in the visitor center, and completing activity pages that encourage discovery learning in an archeologically rich environment. They can also earn an official Casa Grande Ruins Junior Ranger badge and completion certificate.

While visiting Casa Grande Ruins, pick up a Junior Ranger Activity Booklet at the visitor center - it's free. Complete the appropriate activities for your age group and return the booklet to a park ranger or volunteer at the visitor center. They will review your book with you. When your booklet is completed you will receive: A Junior Ranger Badge and an official Junior Ranger Certificate.

The Sonoran Desert

What is a desert?

First, let's start with defining a desert. Areas receiving less than 10 inches of rain a year used to be considered deserts, but that included areas that didn't look like deserts. So now, to be considered a desert, the area receives less than 10 inches of rain and evaporates more than 10 inches of rain per year. There are four deserts in North America: The Great Basin, Mojave, Chihuahuan, and Sonoran.

Where is it?

The Sonoran Desert occurs primarily in Mexico. More than two-thirds of its total area is in Baja California and the state of Sonora. In the United States, most of the Sonoran Desert can be found in the southern third of Arizona, with small areas in southeastern California. It is a subtropical desert and the most complex desert in North America. It has great diversity in geological structures as well as the number and variety of plants and animals.

One reason for the many plants and animals in the Sonoran Desert is that it receives rainfall bi-seasonally. Rain falls in this desert during the winter months and also in July and August. Because the rain occurs twice a year, the plants don't have to wait so long between drinks.

Fun Facts

When you see a What If... symbol like this one, think about the question next to it and try to come up with an answer. Many of these questions don't have "right" or "wrong" answers and are intended to make you think a little harder about an important issue.

Most important, Have FUN!!

What is Trade?

What was exchanged?

The Hohokam didn't have money. Instead, they used items they had created or collected to trade for things they didn't have. Many things were unavailable in the Sonoran Desert, so the Hohokam traded extensively throughout the Southwest. From the west, they acquired seashells, either from the Pacific Ocean or the Gulf of California. From the North, they traded for raw materials like obsidian for making arrowheads. And from the south, where Mexico is now located, they traded for copper bells, macaws, parrots, and seeds for their crops.

Scientific Method

The world is full of questions. What causes volcanoes to form? Why does it rain? The scientific method was developed to provide an unbiased way of finding the best possible answer to a question.

The scientific method was developed so scientists could test possible explanations to questions, and allow others to verify the results. There are five general steps when applying the scientific method:

  1. Make observations
  2. Ask a question based on observations
  3. Form several hypotheses
  4. Test the hypotheses
  5. Make a conclusion

NPS Rangers

What do they do?

The National Park Service and park rangers care for and protect more than 380 national parks, monuments, memorials, preserves, historic sites, seashores and other areas across the United States.

Core Values

The core values of the National Park service are:

What does it mean to be a ranger?

That's a hard question to answer because there are so many different kinds of rangers. All park rangers protect and preserve natural and cultural resources, but they accomplish these tasks in many different ways.

Some rangers fight fires and keep nature safe, others teach about the past. Some study and protect animals or plants. Some maintain structures and roads. All rangers help keep the parks clean. Rangers rescue people, find lost kids, and help make sure everyone is safe. One of the most important parts of being a park ranger is to help everyone understand and appreciate our national treasures so people like you will be willing to care about and care for these wonderful places.

Where is the Water?

When the Hohokam lived in the Sonoran Desert hundreds of years ago, there was more surface water available to help them survive than what we have today. Most of the major rivers in Arizona ran all year round. Along the river beds were riparian areas. These areas included many water-loving plants like reeds, grasses, and cottonwood trees. Fish lived in the rivers and the Hohokam hunted them for food.

In Casa Grande Ruins, Arizona: A Centennial History of the First Prehistoric Reserve 1892 - 1992, A. Berle Clemensen wrote:

"All adjustments in Hohokam society
were tied to the preservation of their
irrigation based society… Between 1200
and 1350, periodic years of high volume
river flow caused a deepening of the Gila
River channel. These times were
interspersed with periods of low water…
Canal intakes had to be moved further
upstream and it became a struggle to
continue farming… Following 1355 times
got worse as more catastrophic flooding
appears to have taken place… sometime
between 1355 and 1450 the Hohokam
abandoned their large, central settlements

What Grows Here?

Cacti, shrubs, and trees grow in abundance in the Sonoran Desert. Temperatures in the Sonoran Desert can reach 120 degrees Fahrenheit and rainfall is less than 10 inches per year. Plants in the desert need to adapt to an environment of little rain and very hot temperatures.

It takes thousands of years and many generations to change what a plant looks like and how it functions. Cacti adapted to the arid land by being able to store large amounts of water in their flesh. Their leaves became spines to help reduce evaporation and discourage animals from eating them. Some shrubs, like the saltbush, have silvery leaves that help retain moisture. The ocotillo and creosote bush lose their leaves entirely during drought periods, reducing moisture loss.

One reason Paloverde, mesquite, and other trees survive in the desert is because their leaves are very small. The Palo Verde tree can continue the photosynthesis process without any of its leaves, because its green trunk and branches contain chlorophyll.

Because of the harshness of the environment, many desert plants grow very slowly, but they can also live a long time. Many cacti can be over a hundred years old and some clumps of creosote bush are believed to be several thousand years old!

The Hohokam

Hohokam is an O'odham or Pima word used by archeologists to identify a group of people that lived in the Sonoran Desert. Hohokam means "those who are gone" or "all used up." What they called themselves is unknown.

Some archeologists think the Hohokam came from a group of hunter/gatherers who moved into the river basins of southern Arizona. Where these people came from is still in question. Some archeologists suggest they came from the south and others think they came from the north. This early group built permanent communities, created pottery, established trade routes and began using agriculture. Archeologists consider these activities to be traits of a distinct culture. No one is sure when the people made the transition from hunting and gathering to farming, but there is evidence in southern Arizona that it may have occurred as early as 3,000 years ago.

The Hohokam were architects, designing and building large structures like the Casa Grande as well as other buildings and walls. But the Hohokam were also farmers and created hundreds of miles of canals to bring water from the river to their fields. Digging the canals was hard work, because of a natural desert soil called caliche . When caliche is dry it's almost as hard as concrete! The Hohokam didn't have metal shovels and picks like we have today, they had to dig the canals with stone tools and digging sticks. Some of the main crops the Hohokam planted in their fields were corn, squash, beans and cotton.

The Hohokam were also artists. They created beautiful pottery and jewelry. Some of the pottery was decorated with geometric designs as well as beautiful drawings of animals and birds. Some Hohokam jewelry was made from seashells from the Pacific Ocean and the Gulf of California. The Hohokam would make the shells into earrings, bracelets, necklaces and rings. The jewelry was unique because some of the shells had etched designs, made from soaking the shell in fermented cactus juice.

What if the Hohokam had stayed in their cities? How would this area be different?

Sonoran Animals

The Sonoran Desert is home to a wide variety of animals, birds and other creatures. Mammals include large animals like the javelina, coyote, Mexican Wolf, bighorn sheep, and bobcat. Smaller animals like the fox, skunk, cottontail, and jackrabbit also live here.

Another mammal that lives in the desert is the bat. These animals pollinate many plants and eat lots of bugs. There are two bats unique to the Sonoran desert: the long-tongued bat and the long-nosed bat .

Even rodents like the packrat, round-tailed ground squirrel, and mice make the Sonoran Desert their home. Many of these animals are nocturnal. By hunting and foraging for food at night, they keep cooler and are less likely to become dehydrated.

About the NPS

What is the National Park Service?

The National Park Service was established on August 25, 1916 by President Woodrow Wilson. It was designed to help protect and conserve natural scenery and historic objects and to give the public a place to go to enjoy nature and history. The National Park Service cares for many different kinds of places, including battlefields, historic homes, natural areas, prehistoric dwellings, rivers, trails and seashores.

The National Park Service Mission

The mission of The National Park Service is to preserve unimpaired the natural and cultural resources and values of the national park system for the enjoyment, education and inspiration of this and future generations. The Park Service cooperates with partners to extend the benefits of natural and cultural resource conservation and outdoor recreation throughout this country and the world.

What if the National Park Service had not been created? What might have happened to the special places protected by the National Park Service?


Archeologists are scientists who study people of the past. These scientists have studied the Casa Grande Ruins for over one hundred years. Archeology is a branch of anthropology, the study of human culture.

Archeology should not be confused with paleontology, the study of ancient life forms such as fossil plants, dinosaurs, invertebrates, etc. Archeologists use the scientific method meaning they make careful observations, ask questions, and form hypotheses or tentative answers to their questions. Then they look for physical evidence to support or reject their hypotheses.

Artifacts, Features and Ecofacts

The most important kinds of evidence that archeologists analyze are artifacts , features and ecofacts. Artifacts are things that people make, use, collect or change, such as tools, pieces of pottery, discarded animal or plant remains. Features are places where human activity has occurred, such as houses, burial places, trash mounds, irrigation canals, or piles of broken shell left by a shell worker. Ecofacts are natural objects found with artifacts or features, such as seeds, pollen, or animal bones. Artifacts, features and ecofacts are studied in context, or the exact position and location in which they are found. As long as an archeological site has not been disturbed or vandalized, the artifacts in the lowest layers should be older than those above, and artifacts found together probably were used together and are about the same age. The study of the layering of objects is called stratigraphy.

Context: Reconstructing the Past

Context can be difficult to determine if a site has been disturbed by weather, animals or human activity. Farming and construction can affect a site, but theft can have a much greater impact. Pothunters ignore laws and don't care if they learn about people of the past. They don't make careful observations or record important information. Usually they are only interested in selling artifacts for a profit, or in adding to their own collections. Archeologists find it difficult to reconstruct the past after a pothunter has passed through. Pothunters and souvenir seekers passed near the Casa Grande before it was a protected National Monument. They took evidence that archeologists might have used to learn about the Hohokam. Sometimes, archeologists studying the same artifacts and features may form different conclusions. This information is provided to introduce you to generally accepted thought on the Hohokam and other cultures. In your research, you may find other conflicting, outdated, or new information about prehistoric cultures.

What is Agriculture?

The early people hunted animals like jackrabbits, cottontail rabbits, and ground squirrels; and also birds, like dove and quail. They even fished in the Gila River, because when the early people lived here, the Gila River had water in it for the entire year.

Probably because there was so much water and food in the area, the early people decided to stay. After a while, they began using up a lot of the resources that were close by and began to run out of food. They could have moved to a new area where there were more things to eat, but instead, the early people turned to agriculture and became what archeologists call the Hohokam.

Agriculture occurs when people begin planting and cultivating crops. The crops can include plants that are native to the region or seeds brought in from other areas. Some of the crops planted by the Hohokam were corn, squash, beans and cotton. One of the greatest difficulties of growing crops in the desert is the lack of rainfall. The Hohokam were very clever and devised a system of irrigation canals to bring the water from the rivers to their fields. This meant they could water more land and produce more crops. With more food available, the Hohokam were able to feed more people, so the population increased. Extra food also meant not everyone needed to work at growing or finding food. Like today, the Hohokam were able to specialize their tasks. There were farmers, but some people may have been potters, basket weavers or jewelry makers. The craftspeople may have traded what they created with the farmers for food and the farmers may have gained storage vessels to store their seeds and crops.

What if we use most of our land to build houses? Where will we grow our food?

How Old Is It?

How do we know?

The Casa Grande was built about 700 years ago around AD1300-1350. How do we know this? There are several techniques archeologists use to determine the age of an artifact, feature or ecofact.

Carbon 14 Dating

Carbon 14 Dating is one technique that can be used on artifacts that were living things. Tiny pieces of the wooden beams that formed the floors in the Casa Grande were found and tested using Carbon 14 dating. Carbon is found in the tissues of all living things including trees. Over time, the carbon decays at a consistent and predictable rate. Scientist used the amount of carbon present in the wood to estimate the age of the Casa Grande. Learn More »


The study of tree rings or dendrochronology, is another method used by archeologists to determine dates. As a tree grows, it produces wider growth rings during wetter years. During dry years, the growth rings are narrow. Cross sections of trees are compared using a tree with known growth years and a tree with an unknown age. The rings on the known tree are 'matched' with the rings of the unknown tree and its age can then be determined. Learn More »

Archaeomagnetic Dating

Archeologists often base date estimates on archaeomagnetic dating, a process that measures the alignments of particles of iron ore and their relation to the migrating magnetic North Pole. When ancient people dug fire pits or hearths and burned very hot fires in them, particles in the surrounding earth become permanently fixed in orientation toward the position of the magnetic North Pole. Slowly over time, the magnetic North Pole changes position, but the iron ore particles remain oriented toward the North Pole's previous position. Archeologists use their knowledge of the migratory path of the North Pole to estimate dates and time periods. Learn More »


Stratigraphy is when artifacts, ecofacts and features are studied in context, or the exact position and location in which they were found. As long as an archeological site has not been disturbed or vandalized, the artifacts in the lowest layers should be older than those above, and artifacts found together probably were used together and are about the same age. Have you every thought about what archeologists from the future might study to find out more about our culture? One place where there is a lot of information is our trash dumps. Every year layers and layers of garbage are deposited, one on top of the other. The stuff at the bottom may be many years old and the trash on the top may have been thrown there yesterday. Learn More »

What is Culture?

What does that mean?

Culture is the way we learn to look at the world and how we function in it. Our culture is taught to us by our families, friends and communities. From these people, we learn what foods to eat, what kinds of houses to build, how to communicate, and how to behave. Cultures can be defined in many different ways: by region, nationality, religion, and race, to name just a few.

Most people are a part of more than one culture. If you are living in the United States, you are a part of the American culture. But there are many other co-cultures living here as well. A co-culture is a culture that is different from the predominant culture. An example would be: the American culture is the predominant culture in the United States and the O'odham culture is a co-culture. Cultures are sometimes defined by the kinds of food we eat, types of clothes we wear, where we live, where we work, the tools we use, the language we speak, and what we do for fun.

Hohokam Pottery and Jewelry

The Hohokam created beautiful shell jewelry including necklaces, bracelets, rings, earrings and pendants. Some of the shells were inlaid with turquoise and others had beautiful designs. To create raised designs on the shells, the Hohokam used a technique called etching. They would paint a pattern on the shell with sap from a tree (the sap is very sticky and doesn’t dissolve in water.) After the sap was dry, they would submerge the entire shell in fermented cactus juice. The cactus juice is slightly acidic and the acid in the juice would eat away the unpainted portion of the shell. After it had been in the juice long enough, they would remove it, scrape off the sap and it would leave a raised design.

Items the Hohokam created have been found hundreds of miles from their homeland. They didn't have wagons or horses, so in order to move their stuff from one place to another they had to walk. It is over 350 miles to the Pacific Ocean from Casa Grande Ruins National Monument. Can you imagine how long it would take and how tired you would be if you had to walk all that way and back again?

The Casa Grande

How was it built?

Father Kino, in 1694, was the first European to call this structure Casa Grande. It is a Spanish word that means 'great house.' The Casa Grande is a 4-story, 11-room structure. It was built about 700 years ago and has been abandoned for about 550 years. It is made of a material called "caliche," which is a type of soil found in the Sonoran Desert. Caliche is a mixture of clay, sand, and calcium carbonate. When it's dry, it is almost as hard as concrete!


Archeologists think the Hohokam built the "great house" using a technique called "puddling." They would dig a pit in the ground until they reached the layer of caliche and then would fill up the pit with water. The water would help soften the caliche to form a mud with a dough like consistency. The Hohokam would then carry the mud in baskets to the construction areas. The Casa Grande is made from about 3,000 tons of caliche. That's about six million pounds!

Why was it built?

What did the Hohokam use this building for? Maybe it was a house. Some say it was a temple or maybe a watchtower. It might have been a place for storing seeds and food. Others think it was used as an astronomical observatory where the Hohokam could keep track of the sun, moon, and stars.