T 3 2 
THE GUIDE TO NATURE 
A MIOCENE CATASTROPHE. 
By David Starr Jordan, Stanford University, California. 
Chancellor Emeritus of Leland Stanford Junior University and Trustee of 
The Agassiz Association. 
[Text and cuts reprinted by courtesy of “Natural History,” New York City.] 
A GREAT many years ago, in 
round numbers let us say about 
2,000.000 B. C., in the age called 
Miocene, the coast line of California 
was in a formative stage. Great de- 
posits of sand and clay were being 
rolled up and folded as 'mountain 
chains, and their nascent peaks and 
ridges formed an archipelago of islands 
with sheltered bays. Here were de- 
veloped immense masses of diatoms, 
microscopic plants, each with a fine 
shell of silica, most of them having the 
form of a flat disk, adorned with thim- 
ble-like depressions and spinules of 
complicated sorts. The number of these 
creatures must be beyond conception 
for, in the locality mentioned below, 
they are piled up solidly to the average 
depth of fourteen hundred feet over a 
territory two and one half miles long, 
and more than a mile and a half in 
breadth. 
In this locality the deposits are free 
from sand, which shows that no fresh 
water came in ; but in other places, over 
dozens or hundreds of miles, from Kern 
County to Orange, the diatom masses 
are interspersed with sand and clay 
and at times completely buried under 
them. From above these buried masses 
exudes the oil called petroleum. It is 
known that each diatom when alive se- 
cretes a minute droplet of this oil. But 
this is a theory ; now to a concrete fact. 
In a little bay on the north side of 
the Sierra Santa Ynez in Santa Bar- 
bara County, just above the present 
town of Lompoc were measureless 
masses of diatoms, covering the bottom 
at first to a depth of about 950 feet. For 
some reason this bay was chosen as the 
spawning ground for a herring of those 
days, known now by the name of Xync 
grcx . 1 This fish was much like a mod- 
1 Fossil Fishes of Southern California. By David 
Starr Jordan and James Zacclieus Gilbert, 1919, pp. 
25-26. 
ern herring, except that its surface 
bones were covered with enamel, a 
ganoid fashion of those Miocene years 
long since gone out of date, so far as 
herrings are concerned. This species 
had, moreover, a row of sharp enameled 
spines along the edge of its belly. 
Something like this still persists in 
many forms of herring — as the men- 
haden and other so-called “saw-bellies,” 
but these are plain nowadays, the 
enamel all off. 
Into the bay at one time came mil- 
lions on millions of these herring — all 
of a size — -six to eight inches long, 
doubtless for spawning purposes. But 
they covered the whole bottom of the 
bay — four square miles — and very even- 
ly' at that. That is the marvel, and 
now comes the catastrophe. For none 
ever got away ; they all lay down and 
died and were promptly buried under 
the diatoms — 350 feet of diatoms at 
least. But the erosion of the years has 
cut into these masses in different places, 
laying bare the strata in which the Xyne 
lie. And whenever one strikes that 
horizon, there are the fish, all in the 
same stratum, none below, nor for 
many feet above. The skeletons are 
all well preserved, not much crowded, 
and the organic part of the skeleton is 
carbonized so that the bones are all 
dark brown or black. 
The accompanying photograph 
shows a slab of diatom rock, 
twenty inches by sixteen, with thirteen 
of these fishes upon it. besides parts of 
others. This seems to be a fair aver- 
age for the whole stratum, and indi- 
cates that the total number in the bay 
1 ,33y, i 95.6° 0 , a mighty school of fish 1 
on the day of the holocaust was about 
About six feet above this deposit of 
Xyne, throughout the basin, there lies 
a thin layer of transparent volcanic 
