Brighton sits on a geological boundary where the White Chalk Subgroup meets thick sequences of Quaternary drift and clay-with-flints. Over two decades of site work between Saltdean and Portslade have taught us one thing: the chalk is never as uniform as the borehole log suggests. We regularly encounter solution features, soft putty chalk zones, and variable rockhead depth within a single building footprint. A test pit programme often reveals more in half a day than a desk study can in a week, particularly where Victorian-era cellars and backfilled wells complicate the near-surface profile. For projects on the London Road corridor or the Kemp Town slopes, we pair this with in-situ permeability testing to assess groundwater flow through fissured chalk before sizing footings.
Brighton's chalk is a dual personality: stiff enough for good end bearing but fissured enough to make groundwater your real design driver.
