138 



HARDWICKE'S SCIEN CE - GOSS IP. 



[June 1, 1867. 



GEOLOGY. 



Toome Bridge Earth and Flint Flakes. — 

 Toome Bridge is a small village on a branch of the 

 Northern Counties Railway, between Randalstown 

 and Castle Dawson — about five miles from Randals- 

 town, and three from Castle Dawson. It is situated in 

 the county Antrim, but is close to the boundary of the 

 county Londonderry. The bridge from which the 

 locality takes its name was a curious old nine-arch 

 structure that formerly crossed the river Bann, 

 which at this spot divides the counties. The 

 bridge was removed some time ago, and the County 

 Boad deviated ; and now the County Boad crosses the 

 river by an iron bridge at a short distance from the 

 site of the former old stone bridge. The river thus 

 "crossed is called the Lower Bann, to distinguish it 

 from the Upper Bann, which, after rising in the 

 Mourne Mountain of the county Down, falls into 

 Lough Neagh at its south end, near the town of 

 Lurgan. The Lower Bann leaves the Lough again 

 at Toome Bridge, and falls into the sea a little to 

 the north of Coleraine. Some fifteen years ago 

 extensive works were carried on at Toome with the 

 view of improving the navigation of the Lower 

 Bann. During the progress of those works, a large 

 number of stone and bronze implements were found, 

 the majority of which are now in the Museum of the 

 Royal Irish Academy, in Dublin. At this time also 

 a bed of earth was cut into, which is now known as 

 Toome Bridge earth, and mounted specimens of it 

 are to be found in the cabinets of most microscopists, 

 few of whom know anything of its whereabouts. 

 The land at both sides of the river, particularly 

 at the western side, is very low for hundreds of 

 acres, and doubtless at one time was covered by the 

 water of Lough Neagh ; indeed, previous to the 

 alteration of the bed of the river, the adjoining 

 lands, and even the County Boad, used to be fre- 

 quently submerged during winter. From indi- 

 cations given in several directions, it is probable 

 that the diatomaceous earth occurs over the whole of 

 the extensive fiat country, and when it has been cut 

 through it shows a thickness of from three to five 

 feet. All the hedgerows along the roads, and 

 dividing the fields, are built of it ; and even bricks 

 have been manufactured from it, and it is so often 

 turned up in the fields that the farmers returning 

 from their work look as white all over as if they had 

 been working in lime all day. An excellent section 

 is exposed all along the river banks. This white 

 earth is well marked, and it seems to rest upon a 

 sunken peat moss. At low water during the 

 summer the peat is exposed, and trunks of trees 

 project from the peat up into the diatomaceous earth, 

 so that the earth itself is newer than the peat. The 

 latter forms in some places the bed of the river. A 

 second iron bridge carries the railway across the 

 river between the above County Boad bridge and the 



Lough, and the peat forms the bed of the river 

 between the railway bridge and the Lough. On 

 this peat there occurs a bed of gravel, and in this 

 gravel there are vast quantities of flint flakes similar 

 to those found in the valley of the Somme, and the 

 ossiferous caverns of England and the Continent. 

 The boys in the locality wade out into the water in 

 the summer, and collect the flakes, many of them 

 very well formed, although mere flakes, there being 

 no chippings upon them. With these flakes, how- 

 ever, there are some arrow-heads and stone celts 

 found, and in some of the adjoining bogs inland 

 flakes, arrow-heads, and celts have been found, 

 similar in every respect to those found in the bed 

 of the Bann.— W. Gray. 



The Petrified Forest. — This celebrated forest, 

 or rather plain of prostrate trees, is about an hour's 

 ride from Cairo. The fragments are scattered about 

 in all directions as far as the eye can reach ; the hills 

 all round and the valleys of the desert are strewed 

 with them. There you see branches in one place, 

 trunks in another, roots in another. Some of the 

 pieces are split up, as if they had cracked from age 

 or the heat of the sun. Many of the pieces are 

 evidently of the palm tree. All the fragments are 

 as hard as the hardest flint. Petrifactions of this 

 kind are found in other parts of Egypt, but not to 

 the same extent. Many speculations and sugges- 

 tions have been offered as to the cause of these 

 petrifactions, but it is beyond doubt that the trees 

 were at one time under water. It cannot now be 

 known whether they grew where they lie or whether 

 they were brought there by a flood (or rather the 

 flood) from a distance. The place, though now a 

 howling wilderness, might have been in the earlier 

 ages of the world a laud of great and luxuriant 

 vegetation. There is no doubt, however, that these 

 trees date fiom the time of the deluge. They may 

 indeed have been uprooted in some distant land, 

 brought by the advancing flood, and deposited where 

 they now lie. Many of these trees measure from 

 40 to 60 feet in length, and several are above 3 feet 

 in diameter. The small fragments may be counted 

 by millions, and thousands lie buried under the sand. 

 They are capable of a high polish, and might be used 

 as ornaments of various kinds. — E. St. John Fair- 

 man. 



Rocks of the Aqueous Deposit behind the 

 Citadel, Cairo. — Immediately behind the citadel 

 at Cairo there is a small range of mountains called 

 the Mokattam mountains, which is almost entirely 

 composed of shells, roots of various vegetable sub- 

 stances, and small branches and roots of trees, all 

 petrified and forming a solid rock. Besides these, 

 sharks' teeth and crabs have been found in these 

 mountains. There is no doubt that these rocks 

 have been deposited by water, and, taking into con- 

 sideration the evidence of other phenomena equally 



