6o 



An intrusion of grey felsite, which lies about ioo yards 

 southeasterly from the deposit, is believed to be genetically 

 connected with the ore body. The rusty color of the schist 

 is due to the decomposition of pyrite and pyrrhotite, with 

 which the schist is highly impregnated. Hot solutions 

 accompanying the felsite magma may have effected a con- 

 centration of the sulphides originally contained in the schist, 

 resulting in the formation of the ore body. The rusty 

 schist occurs not uncommonly in various parts of south- 

 eastern Ontario. The sulphides accompanying it may have 

 been deposited at the time the rock was originally laid down 

 as a shale. 



Fluorspar. Several veins of fluorspar, varying in 

 width from a few inches to six or seven feet, occur within 

 a radius of two or three miles of Madoc. They are all 

 probably post-Ordovician in age, since one of them inter- 

 sects limestone beds of the Black River formation. The 

 others occur in felsite, crystalline limestone and other rocks 

 of pre-Cambrian age. Associated with the fluorspar are 

 subordinate amounts of barite. 



BIBLIOGRAPHY. 



The geology of the Madoc and surrounding areas is 

 described in Part II of the 22nd Annual Report of the 

 Ontario Bureau of Mines, in which references to earlier 

 literature are given. Seven geological maps accompany the 

 report. 



ANNOTATED GUIDE. 

 Toronto to Ivan hoe. 



Miles and 

 Kilometres. 



0.0 Toronto, altitude at water-line of lake 



Ontario is 246 feet (74.9 m.). 

 100.8 m. The country between Toronto and Havelock 



162.2 km. is heavily covered with Glacial and Recent de- 

 posits of boulder clay, sand, gravel, etc., and 

 outcrops of Paleozoic rocks are almost lacking. 

 At Toronto the boulder clay is seen to be rest- 

 ing on Lorraine shales. Thus in the Humber 

 and Don valleys contacts of the shales and 

 Glacial deposits may be seen. 



