812 REPORT—1890. 
by the Millstone grit, but northwards a set of cherty beds comes in between the 
limestone and the Millstone grit ; this begins at Coverhead merely as a thin cherty 
top to the limestone, but the chert gradually develops into a series of cherty beds, 
sandstones, and shales, known as the Black and Red Beds in Swaledale. Still 
further north the cherty beds change into a set of coal-bearing sandstones, grits, 
and shales, known as the Coal Sills, overlain by a thin but persistent bed of lime- 
stone, known as the Little Limestone. 
4, Owing to the deterioration of the lowest Millstone grit in Walden, Cover- 
dale, and on the flanks of Penhill, it is somewhat uncertain what line should be 
taken further north as the Millstone grit base, so as to keep to the same horizon. 
In the author’s opinion the best line (at least the most certain line) to take is the 
tov of the cherty series and its equivalent the Little Limestone. Thus we shall, at 
all events, keep to one and the same horizon. 
5. It is important to notice that the siliceous grits and ganister-like beds that 
occur in the Millstone grit series above the Kinderscout grits, become more pro- 
nounced northwards, so that at length they become regular ganister measures 
similar to the ganister measures of the lower part of the Coal Measures. 
13. Human Footprints in recent Volcanic Mud in Nicaragua. 
By Dr. J. CRAWFORD. 
In this communication the author refers to an article in the Proceedings of the 
Victoria Institute for 1889, reprinted from letters by Dr. E. Flint, and comments 
thereon by Dr. D. G. Brinton, published by the Philosophical Society of Phila- 
delphia. Footprints of men and of wild and domestic animals occur on a bed 
of volcanic mud, now much hardened and overlain by alternations of finer and 
coarser consolidated ashy muds derived from volcanoes, near Lake Managua. ‘The 
footprints are of Indians, with short, broad feet, evidently hastening towards the 
lake. The bed containing them rests on a yellow (so-called Miocene) sand, really 
a consolidated mud similar to those which overlie it, and the whole series of beds 
for at least 10 feet below the bed bearing ‘the footprints is of recent date. The 
author, in illustration of the formation of volcanic muds, instances the great 
‘ Aluvion de Barro’ of 1876, which covered the Plaza grounds in Managua to 
a depth of 5} feet, and also filled up the street previously called Calle Honda 
(deep street), which was 3 feet below the surface north and south of it, so that 
it is now a very important street, on the same level as the adjoining part of the 
city, and called Calle Mercado. 
14. On the Geology of Nicaragua. By Dr. J. CRAWFORD. 
The author divides the country into five areas for geological purposes: 
I. A western section, roughly parallel to the Pacific coast, and including the 
large lakes Managua and Nicaragua, and several smaller crater lakes, some of 
which are filled with fresh water, while others contain large proportions of salts. 
'!'he strata are mainly volcanic ashes, marine and lacustrine beds, with shells, and 
some deposits like glacial drift. The following heights are given :— 
Voleanoes: Viejo, 6,160 ft.; Momotombo (smoking), 6,510 ft. ; Cosequina, 
3,860 ft.; Masaya (large crater), 3,800 ft.; Mombacho, 5,100 ft.; 
Ometepa (hot top), 5,800 ft.; Madera, 5,000 ft. 
Lakes: Fresh-water—Managua, 123 ft.; Tiscapa, 176 ft.; Masaya, 216 ft. ; 
Apoyo, 85 ft. Slightly saline—Nicaragua, 106 ft. Saline—Nejapa, 
168 ft.; Giloa, 138 ft. 
None of the volcanoes is now active, but there are boiling springs and old 
floods of mud, ‘ aluviones,’ which mimic older stratified deposits. 
II. A section north-east of the last consists of Recent delta deposits, Post- 
Glacial brick-earths and cave deposits, Pliocene, Miocene, Eocene, Cretaceous, 
‘Wealden, Oolitic, Permian, and Carboniferous rocks. In this section are found 
nly he 
