*4.6. Analysis of Boulder Sizes*

Variations in boulder size as a function of maximum and minimum length drawn from the data sets (Tables A1–A4) may be plotted separately for each transect using bar graphs. Groupings separated by intervals of 25 cm are plotted in histograms stacked to show the trend in diminishing boulder size as a function of distance from the headland source (Figure 8). The largest boulders in the Almeja CBB occur in Transect 1, the distal end of which is 12 m from the closest rhyolite sea cliff (Figure 5). The range in maximum boulder length in Transect 1 is from 58 to 268 cm (Table A1) but the highest frequency falls within the interval of 101 to 125 cm (Figure 8a). The distal end of Transect 2 meets

sea level at a distance of 52 m west along the curve from the bedrock source (Figure 5). The range in maximum boulder length from Transect 2 is from 62 to 172 cm (Table A2) but the largest blocks fall into an interval a full meter less in size than the largest class in Transect 1 (Figure 8b).

**Figure 8.** Set of bar graphs used to appraise variations in maximum boulder length; (**a**) Size-range and frequency for boulders from Transect 1; (**b**) Same graphic coverage for Transect 2; (**c**) Same graphic coverage for Transect 3; (**d**) Same graphic coverage for Transect 4.

The distal end of Transect 3 joins sea level on the west side of the Almeja CBB, located approximately 160 m down shore from the bedrock source through a curve (Figure 5). The range in maximum boulder length recorded from Transect 3 is from 38 to 164 cm (Table A3) but the largest two populations fall equally into neighboring classes from 51 to 100 cm (Figure 8c). For the most part, boulder populations in transects 2 and 3 overlap in range but the latter includes a smaller population rejected from among the largest 25 samples in all other transects. In contrast, the distal end of Transect 4 intersects sea level on the south margin of the Almeja CBB. At that location, the shore is approximately 230 m along the curve from the same source rocks supplying boulders to the other transect populations (Figure 5). The range in maximum boulder length from Transect 4 is from 33 to 75 cm (Table A4) but by far the largest population occurs within the interval from 51 to 75 cm (Figure 8d).

A similar trend is shown by bar graphs representing minimum boulder length recorded in Tables A1–A4. The range in minimum boulder length from transects 1 and 2 (Figure 9a,b) is significantly greater than found in transects 3 and 4 (Figure 9c,d). By far, the largest populations in transects 1–3 occur in the interval of 26 to 50 cm, although many more clasts in the interval with a maximum size of 25 cm were recorded in Transect 4 (Figure 9d). Clasts with this minimum size are abundant throughout the entire Almeja CBB but were not among the largest 25 samples recorded for minimum length in Transect 1.

**Figure 9.** Set of bar graphs used to appraise variations in minimum boulder length; (**a**) Size-range and frequency for boulders from Transect 1; Transect 2 (**b**); Transect 3 (**c**); Transect 4 (**d**).
