14 On the Caves Perforating Marble 



although frequently covered with reddish and yellow earthy 

 sediment. Throughout this cave, at about 6 feet above the 

 present bottom and water-level, are masses of mud conglo- 

 merates, with water worn pebbles and boulders from J-inch 

 to 3 inches in diameter, and made up of the porphyries and 

 slates which exist in situ on the surrounding hills. These 

 mud conglomerates evideDtly are the undenuded remnants 

 of what was for a long time the original deposit forming the 

 floor of the ancient cave, and may yet be found to contain 

 fossils of scientific value. I have indicated their position on 

 Diagram No. 5. The beds, where visible within the cave, 

 seem to be much thicker than on the weathered surface, 

 and are still full of the parallel earthy seams before re- 

 ferred to. 



TEMPERATURE OF THE CAYES. 



During two visits I made some observations on the tempera- 

 ture of the caves examined. On the first occasion, in August, 

 1882, when the surrounding hills were covered with snow, 

 the thermometer at the entrance to caves Nos. 1 and 2 stood at 

 50° Fahr. ; at a distance of 100 feet within the caves it rose 

 to 58° Fahr. During November of same year the thermo- 

 meter at entrances registered 62° , and at the same place as 

 before, within the caves, it fell to 54°, thus giving a difference 

 of 8° between the external and internal air in each case. 

 This seems to agree with the result of observations recorded 

 elsewhere, " that the air in caves is generally of the same 

 mean temperature as that of the district in which the} 7 occur, 

 and consequently cool in summer and warm in winter."* 

 For instance, during August, the minimum degree of cold 

 registered during a severe frost at the Limestone Creek was 

 20°, or 12° below freezing point, while in November the 

 maximum registered was 80°. Taking the mean of these 

 observations as an approximate mean annual temperature, 

 we have 50°, which I anticipate is about that of the regular 

 mean temperature of the caves, and also that of the Lime- 

 stone Creek valley in which they are situated. Of course 

 this determination is not to be taken as strictly correct, as 

 a more extended series of observations are required to ascer- 

 tain the mean temperature of the place, and it is probable 

 that the maximum and minimum heat is greater and less 



* Boyd Dawkius' Cave Hunting, p. 71. 



