Letters from Hicks, Henry to Charles Lyell, 1 October 1868 - 20 March 1874

Lyell’s summarises the letters as:
- 'The Cambrian group reduced to nothing if all the Longmynd [sic Long Mynd] are Silurian'. Thanking for receiving Elements edition, "there is an unusual charm in your books which compels a careful reading from them". Briefly refutes Mr Davidson’s Primordial Silurian group. 1 October 1868.
- 'Cambrian of Elements'. Divisions of periods, where they start & end, where various Welsh formations fall into those. Small diagram included - intermediate surface [rains?]. 20 September 1869.
-'Sending tables on the Cambrian'. Attached Tables on Cambrian rocks, Hicks thinks most up to date for Cambrian Rocks chapter in Elements. 18 November 1869.
- No summary. Compares Tables to larger amounts of species published from America and continent. Lyell sent Hicks some of Torell’s samples, unlike any plant published so far. 26 November 1869.
- 'Comparison of Torell’s Swedish Cambrian fossils with Welsh'. Comparing samples Lyell sent him to Welsh formations like the Lingula Flags. 6 December 1869.
- 'Dr Hicks Classification of the Cambrian'. Quotes Siluria pg 31 by Sir Roderick Murchison, who classes Welsh formations with those of Bohemia. Debates whether trilobites had eyes and question of light in earliest Cambrian. Includes small table of groups and Welsh formations, divided into Upper and Lower Cambrian, also written out at the end. 16 March 1870.
- 'Barrande’s primordial zone'. Lyell classified Cambrian now. Hicks saw Barrande’s cephalopods, discusses what does/doesn’t fall into his primordial zone, compares again Welsh to Bohemian rocks. 18 May 1870.
- 'Hicks enclosing Homfray on Tremadoc beds'. Continues debating classification of Cambrian, especially Tremadoc and Arenig groups, and Silurian period. Hick sent him [Homfray] queries about his work on these. Looking for organic fossils in Cambrian rocks, believes one day all sedimentary rocks will show signs of sea life, no more ‘agoric’ rocks. 1 enclosed letter from Homfray to Hicks. 1 enclosed copy of a letter from Lyell to Hicks, discussing re-classification of Cambrian relating to Wales May 1870
- 'Harlech & Llanberis Lower Longmynd [sic Long Mynd]'. Hicks’ analysis of Prof. Ramsay and; Mr Bailey on subdivision of Lower Cambrian in detail - e.g. gives Ramsay’s 6 districts of Cambrian Rocks, lots of quotes from their papers and sample/fossil names.1 June 1870 [Note - the first sheet of this letter may be numbered incorrectly, 2557.
- No summary. Comparing Swedish, British and Bohemian species, mentions the arguments of Salter, Barrande and Torell. 6 June 1870. [Note - letter begins on 2564, but 2563 is part of this letter yet comes first].
- 'Returning Torell’s Swedish Cambrian with remarks'. Analysis of fossil samples and what kingdom they belong to, including pseudo-Lyellia corals. Again compares Swedish samples to Welsh, notes colour differences. 9 June 1870.
- 'Thickness of Menevian group at St Davids'. Discusses section of coastal rocks, with their depths and classifications in St Davids, North Wales. 11 June 1870.
- 'On Cambrians chapter / proofs'[and second note added in pencil] 'His priority as to claims of Hicks & others to priority of Cambrian fossils & classification'. Comments and corrections of a piece Lyell asked him to look over, quotes page numbers. Clarifies his own discoveries and involvement with digs. 2 October 1870.
- No summary. Kind receipt of copy of Students’ Elements, Hicks’ upcoming paper will agree with Lyell on the Lower Cambrian. 27 December 1870
- 'Discussion of clarification of Cambrian'. "Several" other geologists [not mentioned] have asked Hicks for a paper on Upper and Lower Cambrian boundaries, to assist with teaching pupils. 22 December 1870.
- 'Second letter on Cambrian & Menevian classification'. Lyell’s divisions all work for Wales, continuing to discuss the divisions for Hicks’ paper. 25 December 1871
- 'Thanks for Students Elements' 20 March 1874.