178 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



ON BLACK LITTORAL SANDS IN LANCASHIRE. 



By James Johnstone, D.Sc. 



On most places in the littoral zone on the coast of Lanca- 

 shire the sand below the surface is more or less black. On 

 the Formby shore, for instance, on the landward side of the 

 channel between the shore and Taylor's Bank there is (or 

 used to be) a cockle-bed, but below the upper two or three 

 inches of clean, yellow sand the substratum is very black. 

 At Piel (in Barrow) there is a dense bed of lugworms on the 

 west side of the railway embankment, and here also the sand 

 beneath the surface is black to grey in colour, the superficial 

 layer being yellow. Close to the embankment there are little 

 gutters containing a few inches of water, and on the sides of 

 these the upper, yellow layer of sand is only about an inch 

 in depth, while below that, and as deep down as one can dig 

 with a spade, at all events, the sand is dense black. Further 

 out towards the low- water mark the upper, yellow layer becomes 

 thicker and the sand underneath becomes grey in colour, and 

 the greyness becomes rather lighter as one goes out away 

 from the shore. 



The dense, black sand close inshore smells offensively of 

 decaying seaweed and sulphuretted hydrogen when it is turned 

 over. When I first collected a sample I dried it in a steam 

 oven and was, for the moment, surprised to find that the 

 colour had disappeared long before the sand became dry. 

 Even in the cold it disappears rather quickly, a mass of the black 

 substance becoming light yellow in about an hour. But under- 

 neath the upper layer of a quarter of an inch in thickness the 

 dense, black colouration was persistent. It was evident that 

 one has to do here with a deposit of moist ferrous sulphide 

 which rapidly oxidises. 



