394 The American Geologist. june, isdj 
so plentifullj^ distributed that in the open prairie the}' present the 
appearance of a vast field of hay-cocks. The}' are without order. 
The bases of many lie nearly contiguous, while others are many 
yards apart. The nearly level earth between the tumuli is more 
or less strewn with pebbles and cobblestones, similar in character 
to those of the mounds. These heaps at once attract the attention 
of ordinary observers as they pass through them on the railway 
train to and from Olympia. To the trained student of Nature 
they inspire a subtle and profound interest, but the attempt to 
solve the prol)lem of their history involves many difficulties. For 
the last twenty years they have been studied with more or less 
care. Several theories have been presented, which require men- 
tion here. 
The speculative hypothesis that the tumuli were built by fish 
while the land was submerged in comparatively still water seems 
improbable from their physical structure. Fish,forraing heaps for 
breeding purposes, would not pack together sand, gravel and cob- 
bles, as in these large mounds. It has been supposed by some 
that the Indians constructed them for burial places, or to clear the 
land. If for burial places, there should be found remains of some 
character to indicate the fact. If to clear the land for agricultural 
purposes, why heap the earth with the cobbles? Again, why take 
so much trouble, involving a vast amount of labor (which is not 
accordant with the Indian character), to clear the stony land, 
while millions of acres lie on every side already quite clear? 
Others have suggested "that they were raised as foundations for 
huts on a wet soil. " The character of the soil of the mounds, 
and of the surrounding region, precludes this theory. It would 
seem that no careful observer can entertain either of the above 
views. 
The remaining theory, and the only one which commands seri- 
ous thought, is that of Prof. Joseph Le Conte,* of California, 
whose opinions should always be approached and viewed with the 
highest respect. He says, referring to the prairie tracts, often 
called "everglades," on which the tumuli are situated: 
*Proceedings of the California Academy of Sciences, Dec. 15, 1873; 
Am. Jour. Sci., Ill, vol.vii, pp. 365-7, April, 1874. See also descriptions 
and discussions of the origin of these and similar natural mounds, by 
A. R. Wallace, G. H. Kinahan, J. Le Conte, W. M. Williams, J. Dur- 
ham, and W. M. Gabb, in Nature, 1877, vol. xv, pp. 274, 379, 431, 530; 
vol. xvi, pp. 6, 7, 34, 183. 
