YORKSHIRE NATURALISTS AT SALTBURN. 



223 



times. Landslips of greater or less magnitude were noticed en route. 

 Just below the village were noticed upon the shore four blocks of 

 Shap Fell granite, varying in diameter from 3 feet to 2 feet. Passing 

 the village of Runswick, the contour of the cliffs changed again. 

 Instead of the receding and easily denuded cliffs of boulder clay, 

 in which the springs and streamlets from the land, aided by the ever- 

 advancing waters of the ocean, make such havoc, thus enabling the 

 Bay of Runswick to gradually but surely extend its area upon the land, 

 the precipitous cliffs of the Lias again appear, having at their base in 

 some places heaps of huge boulders of oolitic sandstone detached from 

 above, in others wide flats of slippery shales extending below low- 

 water mark. Some abandoned ironworks north of Runswick were 

 seen, and we were told their ruin was occasioned in one night by a 

 landslip. In the cliffs, just above the ironworks, there is a fault with 

 a down-throw of about fifty feet to the east. The shales of A. serpen- 

 //////i" overlaid the beach near this point, and Mr. S. Jefferson extracted 

 from their face some large crystals of iron pyrites or sulphuret of 

 iron, perfect octahedrons in shape. Several species of ammonites 

 were also noted, but they were of too brittle a character to be 

 brought away as specimens. Mr. Chadwick, ever on the alert in his 

 special subject, fossil sponges, was successful in finding a small 

 specimen in this locality. Special search was made for a single 

 specimen even of an Aptychiis^ or operculum of an ammonite, but 

 without avail. The works at Port Mulgrave were next passed, where 

 a drift is driven into the cliff and large quantities of the valuable 

 Cleveland ironstone obtained. The immense heaps of this material 

 to be seen presented a good opportunity for studying the character 

 and appearance of this valuable mineral. It was of a decidedly 

 oolitic structure, bluish-grey in colour, and evidently porous. By 

 analysis this rock has been described as a carbonate of protoxide of 

 iron, which could not have been deposited in the sea in its present 

 form, and Dr. Sorby concludes, after a minute and deeply interesting 

 examination of every feature connected with this rock, that the 

 Cleveland stone was a kind of oolitic limestone interstratified with 

 clays containing a large amount of oxide of iron and organic matter, 

 which, by their mutual reaction, gave rise to a solution of bicarbonate 

 of iron — that this solution percolated through the limestone, and 

 removing a large part of the carbonate of lime by solution, left in 

 its place carbonate of iron. The sandy micaceous ' grey shales ' of 

 A. annulatus now appeared, occupying the shore line between Port 

 Mulgrave and Brackenberry Wyke. Many belemnites were exposed 

 upon these shales, and Mr. C. Brownridge, F.G.S., secured a good 

 specimen where the guard projected from a nodule at the end ; the 



July 1887. 



