BULLETIN OF THE BUREAU OF FISHERIES. 
416 
goitrous regions are located or the geologic formation from which the water supply 
springs is the determining factor in the incidence of goiter. He has found regions 
located upon and supplied with water from pure Jura formation, with from 12 to 40 
per cent of goiter, and comes to the conclusion that the boundaries of localities in 
which endemic goiter occurs are purely geographic, such as certain valleys, along cer- 
tain rivers, or the sides of certain mountains. 
To determine whether there is any connection between the geological formation at 
the various hatcheries of the Government where trout are bred and the endemic conditions 
existing in most of them, we have obtained from the United States Geological Survey a 
statement concerning the formation at most of the centers of fish culture throughout 
the country. All the data are included here, whether the station concerned is engaged 
with trout culture or not. In some cases only general information is available. 
No correlation between geological formation and the occurrence of thyroid disease 
is at present even suggested from the data at hand, which is here shown for purposes of 
record in view of its possible future value. Most of the water supplying stations subject 
to thyroid disease arises among the geological formations of primary' order. Only one is 
secondary (Triassic) and only a few tertiary and quaternary, 
ALASKA. 
Yes Bay. — Crystalline .schists, probably Carboniferous. 
ARKANSAS. 
Mammoth Springs. — Probably in Proctor or Potosi limestone. Cambrian system. 
CALIFORNIA. 
Baird. — Baird formation. Carboniferous system. This underlies a bluff of the Carboniferous 
McCloud limestone. 
Battle Creek. — Tuscan tuff with some lava beds. Tertiary. 
Mill Creek. — On border of alluvium of Sacramento Valley, and of Tuscan tuff and lava. Tertiary age. 
COLORADO. 
Leadville. — Crystalline rock; pre-Cambrian age. 
GEORGIA. 
Bullochville. — ^Formation not known. Probably granite and gneiss. Archean gneiss, 
ILLINOIS. 
Quincy. — Burlington and Keokuk limestones; Carboniferous age. 
Meredosia. — Glacial sand and clay. One hundred feet more or less below the surface is Carbonif- 
erous limestone. Same as at Quincy. 
IOWA. 
Manchester. — Devonian limestone with chert nodules. 
Fairport. — At contact of Carboniferous shales on Devonian limestone. 
