Mary Horner Lyell

Mary Horner Lyell (1808–1873) was a conchologist and geologist. She was married to the notable British geologist Charles Lyell, and assisted him in his scientific work. She never become widely known in her own right although it is likely believed by historians that she made major contributions to her husband's work.

Mary Elizabeth Horner was born in 1808. She was the eldest of six daughters of Leonard Horner, a professor of geology who taught in England and Germany. Leonard Horner was eager for all his children to be well educated. Mary became a conchologist and geologist while her younger sister Katharine became a botanist.

In 1832 she married Charles Lyell, with whom she shared not only her love of geology but also a love of literature and friendship connections in the world of literature. Mary's sister Katherine married Charles Lyell's younger brother, Henry.

Mary Horner Lyell is most well known for her scientific work in 1854, where she studied her collection of land snails from the Canary Islands. This study was comparable to Charles Darwin's study of the Galapagos Island finches.

Mary and Charles were scientific partners; she accompanied him on field trips and assisted him by sketching geological drawings, packing their clothes, equipment and specimens, cataloging their collections, learning Spanish and Swedish in addition to her spoken languages of French and German in order to assist with communications, and acting as a scribe when his eyesight failed in later years.

Mary is known to have attended special meetings of the London Geological Society, and it is clear that she had a keen interest and a thorough understanding of geology. She corresponded in writing with Elizabeth Agassiz about the glacial geology of South America, and was present in her husband's conversations with Charles Darwin, later assisting him by sourcing barnacles, which he acknowledged with a letter in which he also discussed the geology of Scottish glens.

A crater on the planet Venus was named Horner in her honour, see List of craters on Venus.