Petrological notes on the Houston Marl

Abstract

In the autumn of 1921 my friend, Mr Cadell of Grange, sent me some specimens of Houston Marl, with the request that I would examine them with especial reference to the possibilities of finding some economic use for the rock. The main object he had in view has not been realised, but some facts have been brought to light which seem worthy of record. The following notes are based on specimens from a burn one quarter of a mile west of Ecclesmachan; from West Binney, one and a half miles west of Ecclesmachan; and from a locality, probably near Ecclesmachan, the exact position of which cannot be fixed; others were obtained from the Geological Survey of Scotland, through Mr D. Tait, from two bores near Blackness—those from No. 1 bore came from depths of 221 feet 6 inches and 240 feet, and those from No. 2 bore from 744 feet. The specimens from surface out-crops have naturally been affected by the weather; they break up readily into small angular fragments, and joint planes are often coated with a dark brown film of oxide of iron, with which some manganese is probably associated. One of the specimens from West Binney showed traces of “ ball-jointing,” a common feature of the Keuper marls of the Midland counties of England. With the exception of a reddish-brown marl “ interstratified with green marl ” in the Ecclesmachan burn, all the specimens have a greenish tinge, varying from very dark, in those from the bores,