—S 2. se 
1045 
THE IGNEOUS COMPLEX. 
The core of the island is largely plutonic rock, in some places felsitic, 
almost a typical basalt, elsewhere a diorite, and again -very much like a 
granite. Though Abella reported granite on this island, so far I have 
seen none, 
This igneous rock is found in all the streams cutting any of the three 
ranges shown in a cross section of the island. A very blue, hard, and 
extremely fine-grained variety was found constituting Mount Maupa, 
one of the landmarks of Cebu. This mountain, with a conical top, rises 
above the range of which it is a part and is very conspicuous from the sea. 
Locally it is referred to as the sugar-loaf mountain, although I am unable 
to detect the resemblance. A porphyritic rock, which is a hornblende- 
andesite, is seen in the vicinity of Compostela, on the tramroad to the 
group of mines back in the hills. 
A conglomerate of varying thickness succeeds above the igneous 
complex. So far as I know, this conglomerate is always present and is 
conclusive proof that the igneous rock is not of the nature of an intrusive 
mass. Were it such, the difficulties of mining might be increased enor- 
mously. 
Stratigraphically, above the conglomerate comes a series which is very 
difficult to demarcate and to separate into its integral parts. In his two 
years’ work on this island, Abella did not attempt to map this series 
separately. It comprises alternating beds of shale, sandstone, and lime- 
stone, generally unfossiliferous. Above this come the coal measures 
proper, consisting of a gray shale at the base, thickness unknown, a black, 
firm coal occuring in at least two seams, the first averaging 1.5 meters in 
thickness, although greater thicknesses have been reported; this is fol- 
lowed by a firm, yellowish-gray, seemingly unfossiliferous sandstone ; 
above this hes a second seam of coal varying from 30 centimeters to 76 
centimeters. This is of a much inferior grade, being characterized by 
shale and slate partings. Above this latter seam is a bedded limestone 
said by Abella to contain nummulites.. In my search through these beds 
I have found no form which | could with certainty class as such. As 
Mac-Pherson,* of the “Comision del Mapa geologico de Espana,’ con- 
curred with Abella in this diagnosis, I shall accept it provisionally. 
In the vicinity of the Guila-Guila property, at the headwaters of the 
Mananga River, I found a limestone formation having about the same 
stratigraphic position as Abella’s nummulite beds, but a rather close 
search revealed no nummulites. However, it is extremely rich in the 
* See footnote to page 109, Abella’s La Isla de Cebu. 
