A few more references to Chalk in Kent, in Patent Rolls of 56 Hy 3 (April 12, 1272):

manor of Chaure

mill in Chaucre

town of Chalcreria

I strongly suspect that Chalk had a calcaria, a lime-kiln or similar, and was not just named because it was a chalky place.

Below is a Google Earth view of the front yard of a house opposite Chalk church.

Keith

Indeed there is one spelling of Chalk with -r-:  Chalcra 1164-5 (Wallenberg Kentish PNs 306).

Could there have been an OE *calcer < Lat calcaria (perhaps with initial palatization under the influence of cealc?).

Keith