242 Geological Society. 



Most of the forms are certainly of Argovian age, and with regard 

 to the remainder the stratigraphical value is problematical. The 

 presence of the ' acanihicus zone,' therefore, must remain doubtful, 

 although on the neighbouring Jebel Ben Sai'dan deposits of that age 

 occur, and indicate a third transgression in Central Tunis during 

 Kimmeridgian times, which brought back the sea and gave rise to 

 deposits of red ammonitic Knollenkalk exactly similar to that of 

 the Lower Oxfordian and the Argovian. 



March 19th, 1913.— Dr. Aubrey Strahan, F.K.S., President, 

 in the Chair. 



The following communications were read: — 



1. ' The Geologv of Northern Peru : Tertiary and Quaternary 

 Beds.' By Beeby Thompson, F.G.S., F.C.S. 



This paper deals with the physiography, physical history, and 

 geology of some 600 square miles of territory in the westernmost 

 part of South America, between the 4th and 5th degrees of south 

 latitude, and between the Andes and the sea. 



The connexion between the surface-configuration of the district 

 and the arid nature of the climate is shown. 



A description is given of the tablazos, raised beaches, 

 quebradas, and Salinas, etc. 



Then follows a physical history of the region, as told by the 

 rocks themselves, from early Eocene times to the present. A great 

 uplift and folding of the rocks took place in late Oligocene or early 

 Miocene times, followed by a comparatively short terrestrial epoch. 

 A subsequent depression allowed of the deposition of Miocene and 

 possibly later beds. 



In what may be considered as recent ages the area has been 

 spasmodically rising. It is shown that the elevation of the near 

 Andes is a comparatively recent event. 



The series of rocks exposed probably attain a thickness of 

 5000 feet or more. The whole is divided into four groups of 

 formations — Recent, Miocene, Oligocene (?), and Eocene, and each 

 of these into sets of beds. 



By far the most important of these groups of formations is the 

 Eocene, in part corresponding to the Tejon of the Coatiuga district 

 of California. This yields abundance of fossils, and is the only 

 series of beds that yield oil. Eight palaeontological zones in this 

 series are established. About 150 species of fossils are recorded, 

 of which the larger proportion are probably new species. 



The origin of the petroleum is traced to animal organisms. 



2. ' The Internal Crauial Elements and Foramina of Dapedius 

 granulatus, from a Specimen recently found in the Lias at Char- 

 mouth.' By George Allan Frost, F.G.S. 



The specimen described was found near the formation known as 

 ' the fish-bed,' in the setnicostatus zone between Charmouth and 



