Interpretation of Pit Structure 1

Please type your answers directly into this worksheet. Do not delete the instruction or change the formatting of the document.  Start typing between the red brackets.  There are five places (including your name) where you will need to insert a diagram or text.

Dendrochronology plays an important role in Southwestern archaeology. This exercise allows you to practice interpreting a set of tree-ring dates from the Duckfoot site discussed in the Mesa Verde module and illustrated in the map below.  Note that each architectural suite has a double row of above-ground surface rooms and an associated pit structure. Note also that bonding and abutting tells you something about the order of construction of the room suites.  The lecture discussed the dating of Room Suite and Pit Structure 2.  This exercise will focus on Pit Structure and then Room Suite 1. 

If you submit archaeological tree ring samples to the Laboratory of Tree Ring Research at the University of Arizona, the lab will typically give you several pieces of information for each datable sample: (1) the species of the tree (which we will not consider in this exercise); (2) the date (in years AD) of the outermost ring of the sample; and (3) a code that tells you if the date is a ‘cutting’ or ‘non-cutting’ date. Non-cutting dates are called vv dates (vv stands for very variable). If you have a cutting date (generally signified by underlining), this means the outermost ring of your sample was actually the outermost ring of the tree, and thus the reported date is the year the tree was cut (or died by some other means). If you have a vv date, this means the outermost ring of your sample was an inner ring of the tree and that the tree lived for an unknown number of years after the reported date. For example, a 200 year old tree cut in AD 800 would give a cutting date of 800 but a sample from the inside of the tree might yield a vv date of 610.

Part I: Stem-and-leaf diagrams

Make a stem and leaf diagram of the following dates from Pit Structure 1 at the Duckfoot site, following the instructions on the “How to make a Stem and Leaf Diagram” sheet.  Be sure to underline the cutting dates in your diagram.  You may create the diagram by typing directly into this document, or by drawing the diagram by hand, scanning it, and inserting the scanned image here.

Dates: (cutting dates are underlined)

831 831 832 832 841 843 844 845

846 848 851 853 853 853 853 854 854 854 856 858 858

859 862 863 863 863 863 863 865 865 865 865 865 865 865 865 865 865 865 865 865 865 865 865 865 865 866 866 866 866 866 866 866 866 866 866 866 872 873

83| 1 1 2 2

84| 1 3 4 5 6 8

85| 1 3 3 3 3 4 4 4 6 8 8 9

86| 2 3 3 3 3 3 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 6

87| 2 3

Part II: Interpretation

Background: Stem-and-leaf diagrams allow you to identify clusters of dates, particularly clusters of cutting dates. Clusters generally indicate periods of activity that involved the intensive harvesting of trees. Trees could be harvested anytime building materials were needed or in advance of planned building in the future.  For example, a cluster that spans several years may result from the stockpiling of wood just prior to construction. Remodeling and repair subsequent to construction may also produce clusters. Also, especially on sites occupied for long periods, a cluster in one structure may represent the salvaging of wood from an earlier structure. There are no hard and fast rules for determining what process resulted in each observed cluster, it is a matter of interpretation (however, there are more and less persuasive arguments), considering all lines of evidence.

Look at your stem and leaf diagram of the dates from Pit Structure 1.  In this part of the exercise, consider only that diagram (you will take other evidence into account in Part III, below).  What clusters of dates do you see?  How might you interpret them? You can use the background information above as a starting point. What would these interpretations tell you about the original date of construction of Pit Structure 1?  About how long it was occupied?  Answers to all of these questions should be presented in a 6-10 sentence paragraph.

What clusters of dates do you see?

There are five clusters of dates which are represented by stem 83, 84, 85, 86 and 87. Each cluster represents ten years.

How might you interpret them?

In stem 83, three leaves show the exact cutting dates of the trees. In stem 84 and 85, each has six leaves that represent the exact cutting dates of the trees although there are also other leaves that cannot be dated according to their cutting dates. In stem 85, 32 leaves have exact cutting dates while in stem 87 only two leaves show their cutting date.

What would these interpretations tell you about the original date of construction of Pit Structure 1?

Using this cluster, one can identify the time at which Pit Structure 1 was set up, which would be around 866. This is true since most of the tree used in its construction range around stem 86. The previous clusters dating suggest that these trees had been cut and stored waiting for construction or had died through other means. Cluster 87 represent the time of remodeling or repair of Pit Structure 1.

About how long it was occupied?

From the year that it was contracted, until the time of remodeling Pit Structure 1 had been occupied for 8 years. That is from 866 to 873.

Part III: Adding additional lines of evidence

Background: Now, consider other lines of evidence that might support or cause you to reevaluate the interpretations you just developed. Look at the plan view map of the Duckfoot Site above.  The earthen material used in the construction of surface rooms was taken from the holes made when the pit structures were dug. Thus you may assume that Pit Structure 1 was built at the same time as the surface rooms in Room Suite 1.

Create another stem-and-leaf diagram for the few dates from Room Suite 1.

Room Suite 1 dates:

822 826 828 828 830 842 843 847 852 854

856 857 858 858

82| 2 6 8 8

83| 0

84| 2 3 7

85| 2 4 6 7 8 8

Write another paragraph that discusses how this new evidence regarding the surface rooms in Room Suite 1 changes your interpretations from Part II.  Answer in one paragraph.

Based on this perspective, the construction of Pit Structure 1 ought to have begun much early. The hole for this structure must have been dug before 822 since this is the time when Room Suit 1 construction began, and the earthen materials were by then available. As a result, the building of Pit Structure ought to have started around 831 based on the dating of its building materials, but may not have been fully completed. Similarly, one can assume that it was finished and then later fully remodeled using new materials around 862.