ANT 4114
Lab 3: Reading Stratigraphy
9/24/2010
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Introduction: In this week’s lab, we are going to be taking a closer look at stratigraphy.
In last week’s lab, we encountered three distinct strats, representing a very simple, but
common stratigraphic profile encountered in archaeological practice. This is a type of
stratigraphy that is characteristic of a non-depositional environment. But stratigraphic
profiles can become extremely complex, particularly in a depositional environment (i.e.,
in the flood plain of a regularly flooding river), or at a multi-component site, which
contains many discreet episodes of occupation. As archaeologists, we need to be able to
decode these complex stratigraphic profiles because this is one of the major ways that we
establish the relative chronology of occupations or depositional events at an
archaeological site. This week’s lab is going to introduce you to a very commonly used
tool in archaeology for graphically representing, and ultimately interpreting, the
stratigraphic sequence of a site. This tool is known as the Harris Matrix.
Instructions: There will be two exercises in this lab. In each exercise, we will be
constructing a Harris Matrix for a different stratigraphic profile. Each exercise will be
completed during class time and then, with the data you collect in class, you will answer
a series of reflection questions. As with previous labs, these reflection questions must be
answered independently, however, for the in class portion of the exercises, you can elect
to pair up with one other person to work out the stratigraphic profiles but everyone must
turn in a completed worksheet (alternatively, you can elect to work alone). Some of the
data from last week’s lab will be use in this week’s lab, so if you were not in last week’s
lab, try to pair up with someone who was. If you cannot, you will not be able to complete
this lab fully.
Part 1: In-Class
Exercise 1:
In this exercise, we are going to draw and analyze a hypothetical soil
profile based on the soil profiles you drew in the lab last week.
Step 1. Recall that the soil profile you drew last week had three strats. Also recall that we
excavated a feature in the middle of the unit, but because it was not on the edge of the
unit, it was not captured in the profile. You will use the data you collected on the depth of
the strats and the location of the feature to draw the hypothetical profile that would have
existed had the feature been bisected by the wall you profiled. Hence, the profile you
draw below should look exactly like the one you drew last week, only the third strat (strat
C) will have the profile of the feature in it, and its dimensions and location should be
taken from the data you already collected. When you label the stratigraphy, each
stratigraphic body must have its own number. Therefore, even if you believe that the two
C strats, now separated by the feature you will draw, originally belonged to the same
strat, you must label them separately (i.e. C1 and C2). Their original depositional
relationship will then be graphically represented in the matrix.
Step 2. In this step we are going to construct our first Harris Matrix. Remember that only
three types of relationships can be drawn into the matrix.
Exercise 2. In this exercise you will receive a more complicated soil profile and you
will be responsible for working out the sequence of deposition, and then representing that
sequence in a Harris Matrix. This is not as simple as it sounds so work it out IN PENCIL
on the matrix provided. You may have to try several times before you get it right.
THERE IS ONLY ONE CORRECT WAY TO DRAW THIS MATRIX. Before you
leave, I will check your matrix and tell you if it is correct or not. If it is not correct, you
must go back and try again. Once you have the correct matrix, you have completed the in
class portion of the lab. If there is time left, feel free to stay and answer the reflection
questions. Otherwise, you may complete them at home and turn them in next Wednesday.
(Note: The soil profile will be provided for you in class on Friday)
Part 2. Reflection questions
1. Why do archaeologists pay so much attention to soil color and texture? What do these
things tell us about the context of the artifacts we find?
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2. (Exercise 1) Considering the law of stratigraphical succession, what can you determine
about the relative age of the feature you found in strat C and the artifacts you found in
strat B?
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3. (Exercise 1) How would your interpretation have changed if the feature had extended
into the strat above (strat B) up to the interface of strat A and strat B?
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4. (Exercise 2) What is the chronological relationship between 7 and 5? How do you
know?
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5. What is the importance of the law of stratigraphic succession in constructing a Harris
Matrix? What is the advantage of using a Harris Matrix when analyzing the stratigraphy
of an archaeological site?
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Exercise 2: Harris Matrix worksheet. Note: You will only need to use a small portion
of the provided cells.