30 University Geological Survey of Kansas. 
that the upper layer may be connected with an 18-foot stratum, 
150 feet below in adeep canyon. The average purity is thought 
to be above 90 per cent., and it has been extensively used as land 
plaster through the San Joaquin valley. Other smaller deposits 
are found in this valley, and Hilgard pointed out some years ago 
that portions of the rock could be burned into plaster of Paris. 
In the northern part of Los Angeles county, in the Antelope 
valley, an area of twenty-five acres is covered with a surface 
gypsum stratum 25 feet thick. The rock is shipped to Los 
Angeles, where it is ground mainly for land plaster, though a 
small amount is made into plaster of Paris and wall plaster. 
In Riverside and Santa Barbara counties gypsum of good 
quality is mined, but the outcrops are apt to be more or less 
broken and occur in Tertiary clays. 
Gypsum also occurs and is worked in Wyoming and Colorado. 
Gypsum in Canada.'4 
Gypsum is found in the Lower Silurian or Ordovician rocks 
in Quebec, in Upper Silurian in Ontario, and in Lower Carbonif- 
erous in the maritime provinces. It occurs in very heavy beds 
through the Lower Carboniferous strata of northern Nova 
Scotia. The deposit is almost inexhaustible, and is shipped 
from Windsor, Cheverie, Walton, and other places, mainly to 
the United States. Gypsum occurs in large amounts at other 
places in Nova Scotia, as near Antigonisti, where a cliff of white 
and red gypsum 200 feet in hight overlooks the ocean. 
It is found in large amount in New Brunswick. It is quarried 
at the Albert mines, where the rock is 60 feet thick, and it is 
calcined in large works at Hillsborough. In the valley of the 
Grand river, from Cayuga to Paris, a distance of forty miles, 
gypsum of Upper Silurian age outcrops in lenticular beds. Gyp- 
sum of Devonian age is seen in strata of 10 to 20 feet thickness 
for seven miles along the Moose river. 
Gypsum occurs in northern Manitoba in two beds, 22 and 10 
feet thick, and northwest along the Mackenzie river; also on 
Salmon river, in British Columbia. 
14. The Mineral Wealth of Canada, Willmott, pp. 105-111, 1897. 
