Petrota and its Stones

Highslide JS
Fig. 4: Active gullies cut through beds of tuffite.

figure 4

Highslide JS
Fig. 5: Erosion disturbs and can completely destroy archaeological sites, but it can also expose sites buried long ago, and even create new sites in various ways. Eroding areas are therefore archaeologically interesting. Here deflation removes fine grain materials from the surface, leaving in place the coarser fraction and thus creating dense concentrations of stones of all sizes - including pieces of flaked silex.

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Highslide JS
Fig. 6: These pieces along with another 44 were collected from 50 sq. meters (sample 0418) in the deflation surface shown in Fig. 5.

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Types of Bedrock, Erosion Patterns

Bedrock is a patchwork of igneous rocks, mainly volcanic such as andesites of various kinds, andesitic tuffs, tuffites, and rhyolites. These rocks formed from the lower Oligocene to the lower Miocene (c. 33-19 Ma). Some of them are highly cohesive and resistant to weathering, others are quite friable. Areas dominated by the latter rocks display distinct patterns of erosion, such as gullies and deflation (Figure 4, Figure 5 & Figure 6).