124 
IOWA ACADEMY OF SCIENCE Vor. XXIX, 1922 
Pleistocene geology in the future, myself included, use greater 
caution in assigning this and similar material to any given age, 
without first having well considered the subject matter from all of 
its various aspects. 
The fact that they are found beyond the northern limits of the 
state eliminates the possibility of their belonging to the Paleozoic 
strata of Iowa ; and the writer being unfamiliar with the physical 
character of the Paleozoic as it occurs in Minnesota and Canada 
cannot therefore throw any light on the question of their true 
age and the location of their parent ledge, other than by means of 
such information as may be gleaned from descriptive matter which 
has previously been published through the various agencies. 
It may also be properly noted that these boulders possess every 
appearance of having been transported an exceedingly great dis- 
tance, as they are of extreme hardness and in spite of that fact 
are well-rounded and worn, all of the edges having been ground 
down by the polishing influence of the ice. By way of comparison 
a large block of Sioux Quartzite lying a few feet away, which is 
about of like hardness shows little if any wear, its angles being 
keen and sharp as though it had just been broken from the parent 
ledge. Assuming that an equal or approximately equal ratio of 
hardness exists between these two specimens, their respective con- 
dition would indicate that the conglomerates had come from far to 
the north of the Algonkian area. A heavy coat of concretionary 
brown iron oxide is evident in splotches upon the surface of the 
boulders, which is also indicative of great age. 
My first interest in the boulders was purely in the nature of a 
Pleistocene study, and after having visited them several times for 
the purpose of making a minute examination of the character of 
the component pebbles in order to be able if possible to determine 
by actual comparison the approximate location of the parent ledge, 
with the view of estimating the direction of the imaginary cross 
country striation made by these boulders in their Kansan journey, 
imagine my intense surprise on finding nestled in a little protected 
nook on the surface of one of them, caused by a concave place 
where a fracture had at one time occurred, a fine little group of 
clean-cut fossil casts of well developed Brachiopoda, in a small 
yellow jasper-like pebble. Owing to the nature of their location 
on the surface and the extreme* hardness and brittleness of their 
matrix, they could not be removed without totally destroying 
them. I therefore made photographs and plaster casts of them 
