The following links provide further background reading on adverse physical conditions
What Lies Beneath? – by Justin Wong | 6 October 2010 | ICE G&S
http://www.ice.org.uk/getmedia/521bf908-ab77-4ea6-8e6b-965fc44ee5e9/20101006_gs_what_lies_beneath_presentation.aspx
The Differing Site Conditions Clause: Time for Change – by David Michael Pronchick (1990)
http://www.dtic.mil/dtic/tr/fulltext/u2/a252588.pdf
Changed Conditions – Common Problems in Caribbean Construction Contracts : by Martyn Bould FRICS MCIArb MAPM
http://www.ebooks.rlb.com//CCM_Article_April_2011_Common_Construction_Problems.pdf
DIFFERING SITE CONDITIONS – WHO BEARS THE RISK? – by Donald O’Toole
www.troutmansanders.com/files/upload/DifferingSiteConditions.pdf
Fertile grounds for Dispute by Brigid Lloyd & Catherine Anderson
http://www.molinocahill.com.au/LiteratureRetrieve.aspx?ID=108884
Differing Site Conditions by Bernard S. Kamine
http://kamineconstructionlaw.com/publications-and-articles/differing-site-conditions/