restricted access Chapter 4: Archaeological Assessment of the Lower Landform
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95 Chapter 4 Archaeological Assessment of the Lower Landform As detailed in the previous chapter,the concentration of charcoal fragments recovered from a sediment core at the south end of the low flat at the south end of the Gap provided an encouraging AMS 14 C result,the interpretation of which could suggest that a surface dating to the thirteenth century AD may be buried there intact.This finding was equivocated, however, by AMS 14 C results from plant macrofossils, namely spruce needles, from strata at similar depths elsewhere on the low flat which showed only recent deposition. To better understand these findings, an archaeological testing program was undertaken to confirm or refute the presence of an ancient buried surface on this low terrace. Given the landform’s strong correlation with historic descriptions of the location of Old Man’s Playing Ground,the identification of the disturbed remains of the rock alignment described by Peter Fidler in 1792, and by George Dawson in 1883 would be a possible result of this testing program, but by no means a guaranteed one.The absence of cairns at the site by the time of Dawson’s visit, for example, serves as a strong indication that flood events on this landform could have more complex effects than the observed rapid aggradation of sediment in recent flood events would suggest.The recovery of any prehistoric cultural material from this landform, however disturbed, and especially of carbon samples from bone, charcoal, or other materials that would allow a reliable chronology for occupation of the site to be derived would greatly enhance our knowledge of the site even in the absence of remains of the rock alignment. Given that Old Man’s Playing Ground is a site with high cultural sensitivity, efforts were taken to limit any impact to verification of the site’s presence rather than extensive excavation.Details of the testing program on the lower terrace are presented in the following sections, while assessment of the higher terrace is presented in Chapter 5. The results of the testing program on the low terrace were negative. No traces of a buried rock alignment were observed,nor were any cultural materials recovered.Subsurface testing,including trenching,shovel tests,and probing,revealed the presence of buried cobbles representing the bed of the former river channel at much shallower depths than anticipated and the accumulated sediment of only recent flood events above this.Fragments of charcoal were frequently observed during excavation, but those pieces that were macroscopically visible were rounded and smoothed, suggesting fluvial transport from other locations. It is likely that the charcoal sampled in the preliminary testing was similarly transported; such fragments are unreliable as indicators of the age of the deposits from which they are recovered. 96 ARCHAEOLOGICAL ASSESSMENT OF THE LOWER LANDFORM While the model prepared from the initial geomorphic assessment (Figure 3.22) predicting older sediments at greater depths and farther from the current river edge is essentially correct, the time span represented by the sediments exposed is far less than expected. Revision to the model is therefore required: while recent overbank events have resulted in rapid aggradation of small-grained sediment, some flood events on the Oldman appear to be of such magnitude that the low terrace undergoes significant erosion prior to redeposition , with transported sediment load over the flat in such cases being of cobble size or greater.The age and frequency of such catastrophic flood events could not be determined in this study,but their occurrence negates the possibility of ancient surfaces surviving intact on this landform. Archaeological assessment: Methods The low terrace runs a total length of nearly 90 m from north to south, and is widest near its south end. A low swale, five to 10 yards in width, runs along the toe of the slope that frames this landform to the south and east;sediment deposition appears greatest on a gently sloping plane from the river’s edge to the margin of the swale. Figure 3.11 shows how the playing ground as sketched by Fidler could have been accommodated by the level space available on this portion of the landform. Of concern in devising a sampling methodology to adequately assess this landform was the risk of failing to observe cultural materials, particularly if they are present but scarce. In traditional shovel-testing survey methodology, probability of site detection is directly related to the intensity of shovel test arrays, but regardless of intensity, the risk of nondetection remains...