Ben Peachs first work for the Survey involved identifying Carboniferous fossils from Fife and the surveying of coalfields. From there he moved to Old Red Sandstone formations and then on to the complex Ordovician and Silurian rocks of the Southern Uplands of Scotland. In the last work he was joined, five years after his first appointment, by John Horne, with whom his name is now inseparably linked as a result of their outstanding work together on the Southern Uplands and the Northwest Highlands of Scotland. A large number of maps and the two huge memoirs of 1899 and 1907 were the result of this collaboration, together with several articles published in the learned journals of the day. This remarkable partnership lasted throughout the whole of their lives: they became known to their colleagues as Castor and Pollux, the Heavenly Twins. As it turned out, the partnership proved to be immensely beneficial to the understanding of Scottish geology. It is a reasonable generality that scientific minds tend to one or other of two extremes, the intuitive and the logical and Peachs ways of thought were intuitive. He could solve a complex problem very rapidly and would only call upon minutely detailed work to confirm the hypothesis later. But thinking such as this is not always well founded and can even be superficial, with the ideas generated not always worked out in complete detail. Indeed some superficiality is occasionally evident in Peachs work, and it is on record that with him spells of frenzied activity were sometimes followed by periods of total indolence. Sir Edward Bailey later wrote of him:
"Peach in matters geological could scarcely read or write; and in all directions found correspondence an anathema. Apart from this use of the picture books on palaeontology, Peach depended for his knowledge of the work of other men upon his supreme power of conversation; and if he had not had companions like Archibald Geikie and John Horne to record his ideas he would today (1952) be little more than a tradition."
While this is an unnecessarily harsh judgement on Peach and ignores his capacity for meticulous and detailed work (as, for example, his Monograph on Higher Crustacea of 1908) it must be admitted that it was Horne who actually wrote the Memoirs and it is quite possible that Peach, left to himself, would never have written up his work at all! Horne, in fact, was the ideal complement to Peach. He had a logical mind and was a careful, accurate and systematic worker. Though lacking Peachs imagination he had the capacity to organize the mapping programme and write up the memoirs afterwards.