Editing Dorking (section)

===Geology===
[[File:Western_Weald_geology_cross_section.png|thumb|Simplified geological cross section of the western Weald, showing how the land was uplifted to form the [[Weald–Artois Anticline|Weald-Artois anticline]] (dashed lines) and the strata as they are today (solid lines).]]

The rock [[stratum|strata]] on which Dorking sits, belong primarily to the [[Lower Greensand Group]]. This group is multilayered and includes the sandy Hythe Beds, the clayey Sandgate Beds and the quartz-rich Folkestone Beds.<ref name=Dines_1933_11-13>{{harvnb|Dines|Edmunds|Chatwin|Stubblefield|1933|pp=11–13}}</ref> The lower greensand was deposited in the [[early Cretaceous]], most likely in a [[anoxic waters|shallow sea with low oxygen levels]]. Over the subsequent 50 million years, other strata were deposited on top of the Lower Greensand, including [[Gault|Gault clay]], [[Upper Greensand Formation|Upper Greensand]] and the [[chalk]] of the North and South Downs.<ref>{{harvnb|Gallois|Edmunds|1965|pp=35–40}}</ref>

Following the [[Cretaceous]], the sea covering the south of England began to retreat and the land was pushed higher. The [[Weald]] (the area covering modern-day south Surrey, south Kent, north Sussex and east Hampshire) was lifted by [[Alpine orogeny|the same geological processes that created the Alps]], resulting in an [[anticline]] which stretched across the [[English Channel]] to the [[Artois|Artois region]] of northern France.<ref>{{harvnb|Gallois|Edmunds|1965|pp=51–53}}</ref> Initially an island, this [[Weald–Artois Anticline|dome-like structure]] was drained by the ancestors of the rivers which today cut through the North and South Downs, including the Mole.<ref>{{harvnb|Gallois|Edmunds|1965|pp=74–77}}</ref> The dome was eroded away over the course of the [[Cenozoic]], exposing the strata beneath and resulting in the [[escarpment]]s of the Downs and the Greensand Ridge.<ref>{{harvnb|Gallois|Edmunds|1965|pp=71–72}}</ref>

In Dorking, the dividing line between the Lower Greensand and Gault clay is marked by the course of the Pipp Brook. In the south of the town, the Hythe Beds take the form of [[Iron-rich sedimentary rocks|iron-rich]], soft, [[grain size|fine-grained]] sandstone,<ref>{{harvnb|Dines|Edmunds|Chatwin|Stubblefield|1933|pp=47–51}}</ref> whereas the Sandgate Beds have a more [[loam]]y composition.<ref>{{harvnb|Dines|Edmunds|Chatwin|Stubblefield|1933|pp=58–59}}</ref> The [[quartz|quartz-rich]] Folkestone Beds have a lower iron content, and contain veins of [[silver sand]] and rose-coloured [[iron-rich sedimentary rocks|ferruginous]] sand.<ref>{{harvnb|Dines|Edmunds|Chatwin|Stubblefield|1933|pp=73–74}}</ref> Running along the north bank of the Pipp Brook (with a width of around {{cvt|200|m|yd|sigfig=1}}) is the outcrop of Gault, a blue-black [[shale|shaly]] clay,<ref>{{harvnb|Dines|Edmunds|Chatwin|Stubblefield|1933|pp=80–82}}</ref> beyond which is a narrow band of Upper Greensand, a hard, grey [[mica|mica-rich]] sandstone.<ref>{{harvnb|Dines|Edmunds|Chatwin|Stubblefield|1933|pp=84–87}}</ref> In the extreme north west of the town, the [[marl]]y Lower Chalk was quarried for [[Lime (material)|lime production]] until the early 20th century.<ref>{{harvnb|Dines|Edmunds|Chatwin|Stubblefield|1933|pp=97–99}}</ref>

[[Ammonoidea|Ammonite fossils]] are found in the north of the town, including ''[[Stoliczkia]]'', ''[[Callihoplites]]'', ''[[Acanthoceras (ammonite)|Acanthoceras]]'' and ''[[Euomphaloceras]]'' species in the Lower Chalk and ''[[Puzosia]]'' species in the Upper Greensand.<ref>{{cite journal |last1=Kennedy |first1=William James |year=1969 |title=The correlation of the Lower Chalk of south-east England |journal=Proceedings of the Geologists' Association |volume=80 |issue=4 |pages=459–560 |doi=10.1016/S0016-7878(69)80033-7|bibcode=1969PrGA...80..459K }}</ref> [[Foraminifera]] fossils have been found in the Hythe Beds adjacent to the Horsham road, to the west of Tower Hill.<ref>{{harvnb|Dines|Edmunds|Chatwin|Stubblefield|1933|p=118}}</ref>