The Tertiary
The Palaeocene Reading beds consist of mottled and yellow clays and sands, the latter are frequently hardened into masses made up of pebbles in a siliceous cement, known locally as Hertfordshire puddingstone. Examples of Reading Beds outliers occur in what are otherwise chalky areas at St Albans, Ayot Green, Burnham Green, Micklefield Green, Sarrat, and Bedmond. The Reading Beds were laid down about 60 million years ago when the area was a river estuary receiving river sediment from land to the west.
The London Clay is a stiff, blue clay that weathers to brown and rests nearly everywhere upon the Reading beds. It represents the time 55 to 40 million years ago when Hertfordshire was once again under a deeper sea but was near enough to land to receive fine mud deposits.
Read more about this topic: Geology Of Hertfordshire
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“Morality is a venereal disease. Its primary stage is called virtue; its secondary stage, boredom; its tertiary stage, syphilis.”
—Karl Kraus (1874–1936)