184;6.] SPRATT ON THE GEOLOGY OF EUBOEA AND BCEOTIA. 71 



the lacustrine deposits ; and here they form a very important feature in 

 the geology of the country, both from their extent and thickness : they 

 cover the intermediate tract between Markopoulo and the foot of 

 Mount Ktypa, opposite Chalcis, a district twelve miles in length and 

 four broad, forming a long chain of hills separating the valley of 

 Tanagra from the Eubceic Channel, but divided by the Asopus near 

 Oropo. In the freshwater deposits over Markopoulo, I found the 

 same shells as at Koumi ; but the fossils in this locality are neither 

 so numerous, so well-preserved, or of such a variety, there being no 

 vegetable remains or fish that I could find or hear of. The shells 

 generally crumble to powder on being extracted from the marly 

 strata in which they are found. 



The lignite occurs in about the same position with respect to the 

 amount of the superior strata as at Koumi. 



The finding of the coal in this district is more recent than at 

 Koumi. A mine was opened about a year since, and is worked with 

 some activity ; the coal being more easily procured and a shorter 

 distance from the sea than the Koumi coal. 



The mine exists at the head of a narrow valley behind Marko- 

 poulo*. The lignite here is found lying near the surface, the supe- 

 rior strata having been denuded down to it ; and when I visited the 

 spot last summer, a portion of the uncovered lignite was burning, 

 the ignition, I was told, having been spontaneous, for which reason 

 no effort was made to extinguish it. The bed of lignite is about 

 eleven feet thick, but thinly laminated throughout, and towards the 

 upper and lower part interstratified by thin layers of a white earthy 

 substance. This was doubtless a sediment deposited during the 

 formation of the lignite, which from its thin lamination appears to 

 have been the result of vegetable matter growing at the bottom of 

 the lake. Some of the separated laminee have notwithstanding a 

 woody texture, and in viewing a small fragment, one would suppose 

 it to be a portion of a tree, the laminse representing the concentric 

 rings of growth. 



The gravel ridge, extending from Oropo to Mount Ktypa, is of an 

 average height of from 300 to 400 feet throughout, the beds lying 

 horizontal. Upwards of 100 feet of the upper portion of the ridge 

 is composed of beds of gravel and red loam, below which I observed 

 about forty feet of yellowish, brown and grey marls, with thin beds of 

 loose sand intervening. I had no opportunity of examining a deeper 

 section of the deposits of this ridge, and could detect no fossils, 

 either in the marls or overlying bed of gravel ; but the mineral cha- 

 racter of the former more resembles the marine tertiaries than those 

 of freshwater origin. 



As the gravel beds contain only fragments of the older rocks 

 which surround the lacustrine formation, the latter must have been 

 covered by the waters in which the Ibrm.er were deposited, and they 

 most probably extended originally over the freshwater limestones 

 also, but not to so great a thickness in the upraised portions as in 

 the intermediate hollows : to the south of the village of Markopoulo 

 * Marked B in Section No. 5. 



