MARINE GEOLOGICAL EXCURSION. lix. 



very remarkable in the " joint," as he calls it, where the two sets of Chalk strata 

 meet each other. On the whole, he concluded that the strata of the Isle of 

 Purbeck generally could be successfully examined only from the sea. 



Publications, $r., of the Geological Survey, An important memoir on the 

 Geology of the Isle of Purbeck, chiefly written by Mr. Strahan, was published in 

 April, 1899, whilst new one-inch maps coloured geologically were issued in 1895-6. 

 This work by Mr- Strahan is an important step in advance of anything previously 

 attempted, and he justly remarks that the district under consideration includes a 

 length of coast which is hardly surpassed in interest in any other part of England. 

 Meanwhile, a geological model of the Isle of Purbeck is now on view at the 

 Survey Museum in Jermyn Street, and a descriptive guide to this, also written by 

 Mr. Strahan and published in 1906, may be had for sixpence. 



" The White Chalk of the Dorset Coast," by Dr. Eowe (Proc. Geol. Assoc., 

 1901). This important paper deals with the zones of the Chalk, and contains 

 some fine photographs, illustrating the geology of the Chalk cliffs, by Sherbom 

 and Armstrong. As regards this particular district, the following paragraph gives 

 the author's impressions: "It is difficult to say which most compels one's 

 admiration, the marvellous beauty of this boldly -sculptured coast or the power 

 and magnitude of the physical forces which have determined a coast-line 

 possessing, in point of interest, variety, and strength of contrast, no parallel 

 among sections of the English Chalk." 



It is this wonderful coast, so extolled by authors both old and new, that the 

 members of the Dorset Field Club are invited to inspect on board the steamer 

 " Empress," on the 9th of July next. The following scheme is suggested : 



The Start. It is proposed to leave the pier at Swanage shortly after the 

 arrival of the 12.8 p.m. train, and to proceed, in the first instance, towards the 

 Foreland, where the detached rock known as Old Harry still laments the loss of his 

 wife. Distance from Swanage about three miles. The chief point of interest 

 here is the termination of Ballard Down in a sea-cliff, where the curving strata 

 of Chalk on the north are thrust over the vertical and hardened Chalk by the 

 Isle of Purbeck thrust-fault. 



Ballard Point, Pmifield Cove, and Swanage Say. Returning south, pass 

 Ballard Point (382ft.), where the basal Chalk and Upper Greensand may be noted 

 dipping northwards 55 -60. In Punfield Cove the Lower Greensand and 

 Atherfield Clay dip to the north at 62 ; these beds are succeeded on the south by 

 Wealden shales, with Cyprids, Paludina, and other freshwater fossils. The 

 Wealden Beds of Swanage Bay consist of soft alternations of red and grey Clays 

 and variegated Sands with lignite ; the cliffs here are under 100ft., with northerly 

 dips from 16-20. Width of the Wealden outcrop 1 mile 2 furlongs. 



Peveril Point and Durlston Say. At Peveril Point the Upper Purbecks are 

 first encountered, and there is much folding and faulting. The Paludina- 

 marble and Burr beds compose this group, the former being noted for remains 

 of the Swanage Crocodile, which has lately been found also in the Wealden 

 shales of Atherfield (Isle of Wight). It is calculated that this reptile 



