wick ▁arrived ▁in ▁his ▁gig ▁at ▁The ▁Mount , ▁Sh rew s bury , ▁to ▁take ▁Charles ▁as ▁his ▁assistant ▁on ▁a ▁short ▁ge ological ▁expedition ▁mapping ▁str ata ▁in ▁Wales . ▁That ▁evening ▁Charles ▁told ▁of ▁a ▁tropical ▁shell ▁found ▁in ▁a ▁nearby ▁gra vel ▁pit ▁and ▁was ▁im pressed ▁when ▁Sed g wick ▁respond ed ▁that ▁it ▁must ▁have ▁been ▁thrown ▁away ▁there , ▁as ▁it ▁contrad icted ▁the ▁known ▁ge ology ▁of ▁the ▁area . ▁This ▁made ▁him ▁real ise ▁" that ▁science ▁consists ▁in ▁grouping ▁facts ▁so ▁that ▁general ▁laws ▁or ▁conclus ions ▁may ▁be ▁drawn ▁from ▁them ." ▁Sed g wick ▁aim ed ▁to ▁investigate ▁and ▁correct ▁possible ▁errors ▁in ▁George ▁Green ough ' s ▁ge ological ▁map ▁of ▁ 1 8 2 0 , ▁and ▁to ▁trace ▁the ▁foss il ▁record ▁to ▁the ▁earliest ▁times ▁to ▁re but ▁the ▁uniform itar ian ▁ideas ▁just ▁published ▁by ▁Charles ▁Ly ell . ▁ ▁On ▁the ▁morning ▁of ▁ 5 ▁August ▁they ▁went ▁from ▁Sh rew s bury ▁to ▁L lang ol len , ▁and ▁on ▁ 1 1 ▁August ▁reached ▁Pen rh yn ▁Qu ar ry . ▁After ▁less ▁than ▁a ▁week ▁of ▁doing ▁hard ▁practical ▁work ▁Charles ▁had ▁lear nt ▁how ▁to ▁identify ▁spec im ens , ▁interpret ▁str ata ▁and ▁general ise ▁from ▁his ▁observations . ▁ ▁Then ▁he ▁went ▁off ▁on ▁his ▁own ▁to ▁collect ▁samples ▁and ▁investigate ▁the ▁V ale ▁of ▁Cl w yd , ▁looking ▁in ▁vain ▁for ▁the ▁Old ▁Red ▁Sand stone ▁shown