Grid Excavation Method or Wheeler Kenyon Method in Archaeology

There are four main types of archaeological excavation. Those are the grid method, open area method, trench method, and quadrant method. Among them, the Grid Method Excavation in archaeology is quite the topic, as it holds significance in archaeological excavation. So, this article is to look into the grid method of excavation in archaeology.

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Introduction to the Grid Excavation Method in Archaeology

The grid method is one of the major excavation types in archaeology. Sometimes, we call these types of archaeological excavations excavation methods, considering the unique characteristics each one has. However, it is best to say that there are four archaeological excavation types that differ from each other due to the uniqueness of the methods used in each.

Grid-method excavation was invented by Mortimer Wheeler in Verulamium excavations in 1930–35. Later, Kathleen Kenyon refined this method in her excavations at Jericho in 1952–58. Hence, we also refer to this method as the Wheeler-Kenyon method in archaeology, the wheeler box grid method, or the box grid method.

In this method, we divide the archaeological site according to a grid system. Then we choose which grid unit or units to excavate. Then we execute the excavation, following the grid lines precisely, leaving a precisely aligned grid on the ground. Therefore, the excavation site appears like a perfectly oriented and perfectly cut square pit, regardless of the landscape features such as slopes. That makes this method and this type look so systematic.

History of the Grid Excavation Method: Beginning of the Grid Excavation Method in Archaeology

As mentioned above, Mortimer Wheeler invented this method in 1933–35, and Kathleen Kenyon refined it further in 1952–58.

As a pioneer in systematic archaeological fieldwork, Wheeler emphasised the importance of recording both horizontal and vertical dimensions equally in excavation. He wanted to record the depth and time of the excavation, along with the length and width. Hence, he invented the grid method. As he mentioned, this method is for excavating larger areas. In today’s terms, it is to apply for “area excavations”.

Wheeler addressed the issues that existed with excavations at that time, and he discussed several requirements that should be there for a successful area excavation. The requirements he discussed are as follows:

• Clear and reasonable divisibility for effective recording and control
• Room for progressive expansion without compromising initial datum lines
• Preservation of complete vertical sections at multiple points until excavation is complete
• Potential for integration into broader regional excavations
• Easy access for soil removal without disrupting the site’s layout
• Enough openness to provide light for inspections at various depths

So, in order to fulfil those requirements, Wheeler invented the grid method. Then he practiced this method in his excavations of Maiden Castle in the UK in 1937 and Harappa, Arikamedu, and Brahmagiri in Colonial India.

However, addressing the disadvantages of the grid method of excavation, archaeologists introduced open-area excavation a few years later. But, since its origin, many archaeologists have applied the grid method to excavating archaeological sites.

Characteristics of Grid Excavation Method in Archaeology

Obviously, the main unique characteristic of grid excavation method is its grid layout with baulks. But there are several other important characteristics of grid-method excavation in archaeology. For easy understanding, all of those can be listed as follows:

The Grid Layout in Excavation

As said earlier, it is laid out according to a grid. What is important to understand here is that laying out a grid before excavation is not grid-method excavation. Because, in any archaeological excavation, laying the grid of the site happens as a necessity. That is a common requirement. What we call grid method excavation is the systematic and scientific digging of earth according to a grid system laid beforehand, leaving the grid system physically appear on the excavation site.

Baulks: the Unexcavated Spaces Between Pits

Baulks are the most important physical feature in grid-method excavation. Though the grid is laid and usually a grid line does not have any thickness, archaeologists leave spaces in between two grid squares unexcavated. Why and how? Well, when they laid the grid, they divided each square into nine smaller but identical squares. And they separate a 50-centimetre space between each square. And they do not excavate these spaces. They leave them unexcavated. So, they appear as walls in between each square pit.

Precise Positioning and Orientation on Earth

Archaeologists position this grid using a reference point called a bench mark. A bench mark is an indicator established by survey officers to indicate how much that exact point on earth is above or below the main sea level. And these bench marks are aligned with GPS coordination points. So, archaeologists take the measurements from this known source to the site and calculate the precise position of the site on the earth. They lay the grid and conduct the excavation aligned with the grid, as mentioned earlier. That makes the excavated pits in this method precisely positioned and aligned with cardinal directions, altitudes, and longitudes.

XYZ Recording Method

Wheeler introduced the xyz recording method for excavations along with the grid method.

• x = the distance to the antique form the west bank/end,
• y = the distance to the antique from the south end,
• z = the distance to the antique from the main sea level mark of the site.

­Both Vertical and Horizontal Excavation

There are two types of excavation, considering the direction of the excavation. If the excavation extends deeper from top to bottom, we call it vertical excavation. If the excavation extends from side to side, we call it horizontal excavation. Generally, before the grid method, most of the excavations were vertical since they always went from top to bottom. Wheeler introduced horizontal excavation for the first time with this grid method. In horizontal excavation, the area of the excavation through the horizontal plain is larger than the depth of the excavation pit. Generally, area excavations are horizontal excavations.

Here, horizontal or vertical does not mean the way the soil is removed on a smaller scale. It means how the excavation pit is placed on the site. If it is a deep pit, it is a vertical excavation. If it is a wide and lengthy pit, it is a horizontal excavation. However. Wheeler initiated the horizontal excavation for the first time with this grid method. And, most importantly, the grid method can facilitate vertical excavations too.

Advantages of the application of Grid Excavation Method in Archaeology

There are many advantages to the overall application of the grid method in archaeological excavations. As mentioned above, fulfilling the requirements Wheeler outlined is an obvious advantage of this method. The other advantages are noteworthy, as follows:

Easy for Recording

Due to the separation from baulks, it is easy to carry out precise or, at least, accurate recording of the excavation. Since each excavate pit has its own 4 banks, which serve as vertical plains of record of the excavation, precise measurements of findings are much easier without much advanced technology.

Provides A Series of Vertical Plains of the Excavation

The baulks as vertical plains of the excavation provide a demonstration of stratigraphic variations across the entire excavation site. This helps with associating discoveries with specific layers. This has proven to be useful as some of the sites are located in uneven terrain and contain evidence from prehistoric times.

Relatively Economical

In terms of time and energy, the excavation is easy to manage throughout the whole time, with baulks providing separation and easy access for each pit. Discharging dug soil with wheel barrows is much easier with baulks. Wheeler excavations at Harappa provide a prime example of that.

Relatively Low Destructive

Excavation is indeed the destruction of preserved material data. But, unlike open-area excavation in which there are no baulks, grid excavation with baulks provides an easy path for the discharging process of dug-out soil and for other tasks that involve a lot of walking inside the excavation area. Therefore, as the baulks provide easy passageways and only the excavators have to be on the ground being worked, the possibility of destruction of the working soil or of the context of the excavation is very low.

Easy for roofing

The excavation site is more resistant to sudden flooding and rain, such as environmental hazards, as it has baulks, which are ideal for handling rain covers and for discharging flooded water in pits. And even saving one pit without letting it become contaminated with rainwater would be possible with this method. Furthermore, if such an unavoidable disaster happened, the baulks would remain untouched, unless they were destroyed too.

Disadvantages of the Application of Grid Excavation Method in Archaeology

As well as the several noteworthy advantages of the overall application of the grid method, there are some disadvantages too. Those can be noted as follows:

Incapable of Revealing the Whole Perspective of the Field

The baulks separating the pits obstruct the view of the entire horizontal plain of the excavation. The perspective or view of the site after excavation is important in comprehending the site and its historical evidence.

Incapable of Revealing the Discoveries Entirely

Due to the baulks, as the revealed space is separated by them, the unearthed discoveries, such as structures, are left to be separated by the baulks, obstructing the entirety of them.

Incapable of Providing A Full Record of the Horizontal Plains

The entire horizontal plain is separated due to the separation from baulks. All horizontal planes of each square pit must go through a time- and effort-consuming process to get a perspective of the entire horizontal plane, but that too without the areas left for baulks. Hence, throughout the whole excavation, with each layer and with each context, there is no record of a full horizontal plain except that of the photograph of the site before the excavation begins.

Baulks leave A Considerable Amount of Unexcavated Mass

Important evidence can be fully or partially hidden in the areas left to remain unexcavated as baulk.

No Record for Baulks

In this method, after the excavation, if the discovery is structural evidence that has to be conserved at the site, the baulks would also be dug out. But there is no record for baulks. Hence, as mentioned earlier, the risk of missing out on the archaeological value of antiques found in baulks is unavoidable. Perhaps the most important material to remain unearthed from the whole excavation is a piece of pottery found inside a record-less baulk. So, unless the excavation of the baulks is done with special attention and a record, digging out the baulks after the excavation is a permanent and utter destruction.

Not applicable for sites for which layers have not been identified

Only if the layers of the site have already been identified and the contexts spread over large extents in both dimensions would this method be applicable. Otherwise, small contexts would be completely missed by leaving vertical sections unexcavated as baulks, as mentioned above. Therefore, the applicability of the method is problematic.

Baulks could Collapse

As the pits go deeper or if the soil is not that compacted, the baulks could collapse, destroying important evidence of the site. Compared with open-area excavation, collapsed banks of the grid-method excavation would destroy more area of an archaeologically important site.

Read the full article>>Open Area Excavation in Archaeology

Summary

In order to excavate large areas systematically and thoroughly, Mortimer Wheeler invented the grid method of excavation, and Kathleen Kenyon refined it. Grid Method Excavation stands for the most precisely positioned and rented scientific method of digging the earth in archaeology. It does not mean an excavation after laying out a grid system. Instead, it means an excavation takes place aligned with the grid system, leaving a physically appearing grid on the ground. The main feature of this method is its grid layout and baulks. This method has its own high sides, such as facilitating precise recording and execution of the excavation. And also, this method has its own downsides, such as obstruction to the entire excavation profile.