The Geology and Landscape of Hertfordshire

Photo:Simplified outcrop map of the Chalk formations exposed in Hertfordshire

Simplified outcrop map of the Chalk formations exposed in Hertfordshire

Hertfordshire Geology and Landscape, published by Hertfordshire Natural History Society, 2010

Photo:John Catt, centre, with colleagues, at Reed Pit (TL 359370), showing Glaciotectonic thrust slcie of Lewses Nodular Chalk Formation

John Catt, centre, with colleagues, at Reed Pit (TL 359370), showing Glaciotectonic thrust slcie of Lewses Nodular Chalk Formation

Hertfordshire Geology & Landscape, ed. John Catt, 2010

Talk by John Catt to April 2012 meeting of the Society

Report by John Wassell

John Catt was the general editor of Hertfordshire Geology and Landscape published in 2010 by the Hertfordshire Natural History Society. He noted that the book had been proposed in 1950 with each chapter written by a different author and pointed out that had only been the editor since 1973 and that the last chapter was received in 2010! 

The main features of the Hertfordshire landscape result from the sequence of sediments (Chalk, Reading Beds, London Clay), which were gently folded during the later geological periods.  50 million years of erosion removed most of the early Palaeogene deposits from northwestern parts of the county, leaving a thin veneer of Plateau Drift over the Chalk of the Chiltern Hills.  About 0.5 million years ago a glacier invaded the Vale of St Albans, which had been the valley of the Thames since about 2.5 million years ago.  This diverted the Thames into its present course through London.

The local puddingstone was described (flint pebbles cemented by silica) and he noted that the precise origin of flint is not known although several theories exist.

The coprolite deposits that are found in Bedfordshire, Cambridgeshire and the northern edge of Hertfordshire are natural phosphates and not dinosaur droppings!

Copies of the book Hertfordshire Geology and Landscape (2010, Herts. Nat. Hist. Soc.) were available for sale (£34) at the meeting.

This page was added by Rosemary Ross on 05/06/2012.

If you're already a registered user of this site, please login using the form on the left-hand side of this page.