83 REPORT— 1870. 



On the Mountain Limestone of Flintsliire and part of Denbighshire. 

 By G. H. Morton, F.G.S. 



The author pointed out that in Flintshire, within fifteen miles from Livei-pool, 

 there is a prominent ridge of Carboniferous or Mountain Limestone. It extends 

 continuously from Prestatyn on the coast of Wales to Llandegla, a few miles north 

 of Llangollen, the distance being twenty-one mUes, and the strike of the limestone 

 N. by S.E. and S. Instead of describing the formation generally, he had se- 

 lected what appeared to be the four most favom'able localities as centres of obser- 

 vation — Mold, Holywell, Newmarket (Flintshire), and Llangollen. He alluded 

 to the country around or near these places, for neither Mold nor Holywell are 

 actually upon the Mountain Limestone. Llangollen was included because of the 

 grand section presented by the Eglwyseg rocks, about a mile from the town. 

 The distance of the localities from each other is as follows : — From the Llangollen 

 limestone district to that of Mold, eleven miles ; from the Mold limestone to that 

 of Holywell, six miles ; and from the Holywell limestone to Newmarket, nine 

 miles. The Eglwyseg rocks present a magnificent section of the Mountain Lime- 

 stone, all the beds being exposed (except those at the base) at the western outcrop, 

 in a ravine with precipitous cliffs on each side. The highest strata are at the top 

 of the clilfs, half a mile to the west, at an elevation of 700 feet, the estimated 

 thiclvness of the limestone being 1200 feet. The Millstone-gi-it of the Geological 

 Sm-vey succeeds the limestone, and is about 800 feet thick, coal being above it at 

 Tyfyuuchaf. One mile and a half to the west of the town of Mold there is a fine 

 section of the Mountain Limestone. The vertical section of the sti'ata at Newr 

 market is compiled from three horizontal sections, which each show the thickness 

 of a subdivision. The upper, middle, and lower limestones are on the surface 

 disconnected by faults, but the relative geological position of each is obvious. 

 The lower gi'ey and black limestones rest on Silm-ian strata, and are 750 feet thick 

 at Moel Iliraddug. The middle or white limestone, 360 feet thick, is very different 

 from any of the Hiraddug strata, as it is also from the upper black and grey limer 

 stones and shales, 300 feet thick, which crop out from imder the overlying shales 

 and sandstones of the Millstone-giit. In each of the four localities the Mountain 

 Limestone admits of division into an upper, a middle, and a lower subdivision, 

 each having distinct lithological and palaBontological characters. 



Appended to the paper was a list of 120 fossils found in the district de- 

 scribed. An analysis of the list showed some interesting results. Excluding 

 a few fish-teeth and scales and plants, all of which occur in the upper lime- 

 stone, it appeared that the lower limestone does not contain any species pecu- 

 liar to it, for some of them extend upwards into the white or middle limestone, 

 whilst others pass up to the highest subdivisions. The earliest species, prin- 

 cipally found at the base of Moel Hiraddug, are Spirifcra lineata and Syringo- 

 pora reticulata, and they continue upwards through the whole of the Mountain 

 Limestone. These two species, with a Lcjndodenclron and another plant, seem to 

 have been the first colonists that settled do^^m in the Carboniferous sea of North 

 'Whales. The middle or white limestone presents 28 species which are peculiar to 

 it (of course common species elsewhere) ; but of these, no less than 23 have only 

 been found in the limestone ridge at Axton, Newmarket. This assemblage of 

 species in such a limited area is extraordinary. In the upper limestone 23 species 

 have been found to be peculiar to it ; but they are all of rare occiu'rence, only single 

 specimens having been found of about half of them. The common fossils have a 

 considerable range, while those peculiar to certain subdivisions are mostly rare forms. 



On some Future and Past Changes of the Eavth^s Climate, 

 By E. A. Peacock, C.E., Jersey. 



These important changes, he believes, are due (1) to rain and rivers, (2) de- 

 midations, (3) risings and sinkings of land, (4) the gi-eat range of temperature from 

 — 58°F. in interplanetary space to -1-150° and more on various parts of the earth's 

 surface, even in temperate climates. These will accoimt for a future warm and 

 afterwards for a cold period, and for a glacial and a coal-period in the past. 



