143 



(4.8 km.) south exposing white, evenly-bedded anhydrite, 

 probably belonging near the base of the Windsor, folded 

 in a flat syncline with succeeding anticline, and striking 

 S. 6i° E. The average strike of the Horton beds is about 

 S. 57° E. 



The writer has made only a very rough estimate of 

 the thickness of the Horton series. It is thought to be 

 in the neighbourhood of 1,025 feet (312 m.) in the southern 

 limb, while but 400 feet (122 m.) more or less is seen in the 

 northern limb. 



GEOLOGIC AGE OF THE HORTON SERIES. 



The older geologists, Brown, [7] Jackson, Alger, and 

 Gesner, [8] regarded the gypsum or Windsor series as 

 equivalent in age to the New Red Sandstone, i.e. the Trias- 

 sic. The Horton as a consequence, as well as from its 

 plant remains, was thought to be a development of the 

 Coal Measures. In 1842 Logan [9] visited the sections, 

 and considered the Horton a phase of the gypsiferous 

 series, assigning both to the Triassic. However, he sub- 

 mitted some of the Windsor fossils to de Verneuil and 

 Count Keyserling who regarded them as identical with 

 species from the Permian deposits of Russia, the Zechstein of 

 Germany, or the Magnesian Limestone of England. 

 Murchison [10] in his anniversary address to the Geologi- 

 cal Society of London in 1843 also contributed to this 

 view. However, Lyell's visit to the localities in 1843 

 initiated a new correlation. Fortified by both strati- 

 graphical and palseontological evidence he announced the 

 age of the gypsum formation as well as that of the Horton 

 beds, to be Lower Carboniferous and therefore distinctly 

 earlier than the overlying Productive Coal Measures. 

 Of the Horton he writes: [11 p. 209] "Both in the Windsor 

 district and on the Shubenacadie, I found an intimate 

 association between strata containing mountain limestone 

 fossils, masses of gypsum, and coal grits, with Sigillaria 

 and Lepidodendron, but no seams of pure coal in this 

 part of the series." His general conclusions were abund- 

 antly verified by the work of Dawson [3, pp. 252-7]. The 

 latter was, indeed, the first to give clear expression to the 

 division of these beds into two distinct formations, naming 

 what he considered the lower, the Horton series or Lower 



