390 



including Ammonites Walcottii, A. undulatus, Nucula (nov. spe.), 

 Inocercimns dubias, Belemnites acutus, B. tubularis, and B. pencilla- 

 tus, &c. &c. 



Below this point the sloping sides of the escarpments are obscured 

 by accumulations of the detritus of the superior formations, and the 

 same accumulations extend in the form of gravel and sand over a 

 great portion of the low country around Cheltenham, the lias pro- 

 truding in small knolls. At Cheltenham the superficial beds of the 

 lias marls are loaded with the Gryphcea incurva, Ammonites subar- 

 matus? , and a small species of Ammonites, which is very abundant, 

 the strata being highly pyritous. Towards the base of the formation, 

 thin bands of compact lias limestone occur; and at Comb Hill, 5 

 miles N.W. of Cheltenham, these dark coloured hard bands are un- 

 derlaid by thick beds of white lias enclosed in thinly foliated, black 

 shales, which are seen to be incumbent on the green and red marl of 

 the new red sandstone, the whole dipping to the S.E. 



(5.) New Red Sandstone. The author describes merely the hard 

 green and red marl, or upper member of this formation, which is 

 in immediate contact with the lias, on the left bank of the Severn. 



Dislocations in the Cottesivold Hills. — Remarkable instances of dis- 

 ruption are exhibited in many upland coombs and valleys, where the 

 marlstone or surface of the lias is laid bare, and the strata of the 

 great and inferior oolites, on opposite sides of such depressions, dip 

 in different directions and at high angles, frequently inclining in- 

 wards or below the superior masses of the hills. Seeing that the 

 overlying slaty beds of the forest marble usually maintain their 

 horizontality, and that the above derangements are partial, the 

 author refers them to local subsidences, which may in many cases have 

 been in great measure occasioned by the undermining effects of 

 springs, acting upon the pyritiferous and decomposing beds of the 

 lias. 



Mineral Waters of Cheltenham. — The upper strata of water in the 

 lias of Cheltenham containing 27 parts of chloride of sodium, and 

 \1\ of sulphate of soda; whilst the water obtained by the deepest 

 sinkings contains 72| parts of the chloride of sodium, and only 6f 

 of the sulphate of soda, the author was led to believe that the true 

 source of the sea salt in these waters is the new red sandstone. He 

 was confirmed in this conjecture by observing that the mineral waters 

 occurring along the edge of the escarpment where the lias is very thin 

 and directly incumbent on the red marl, are almost pure brine springs 

 (Gloucester, Tewkesbury, &c). By the dip of the strata to the S.E. 

 these salt waters must necessarily be carried to considerable depths 

 below the town of Cheltenham; and he conceives that they are raised 

 to (heir original levels by cracks and fissures, and passing through cer- 

 tain soft and pyritous beds of the lias, obtain their peculiar medicinal 

 properties. Geological evidence is thus brought in support of the views 

 of Dr. Daubeny, which explain under similar circumstances the che- 

 mical changes of muriated into sulphated waters. — See Phil. Trans. 



