232 IOWA ACADEMY OF SCIENCE 
loess and had it not been for the ditches their presence would not 
have been suspected. 
About the year 1873 the writer’s father dug a well near the 
center of the northeast quarter of section 33, township 96, range 
6 west, on the divide between Turkey and Yellow rivers along 
which ran the Old Military Road from McGregor to Fort Atkinson, 
and about one mile northeast of Postville. We have a very dis- 
tinct recollection of the formations encountered but can only give 
the thickness of each approximately. 
After penetrating the usual soil and perhaps 8 feet of loess, 
yellow boulder clay was struck. The well was dug to a depth of 
50 feet when bedded limestone rock was struck. (Bed No. 8, Ma- 
quoketa Shales. See page 484, Vol. XV, Iowa Geol. Survey.) The 
well was a dry one, but was subsequently drilled 15 feet deeper 
through the limestone into the blue clay (Bed No. 6) where an 
abundance of water was found. 
About half way down, i. e., at 25 feet, a “forest bed” was struck. 
This bed was several inches in thickness of black earth containing 
much decayed wood and twigs. One piece about a foot long which 
had the appearance of a root prong from an old stump was taken 
out. This was kept as a curiosity for a year or two until it finally 
fell to pieces. 
Beuw the “forest bed” the clay was blue, and in addition to 
the granite pebbles and boulders of the yellow clay, there were 
boulders of quartz and various other kinds of blue, green and red 
stone, new and strange to the boys who were engaged in the rather 
hard labor of hauling it out with windlass and chain. 
There can be little doubt that the two clay formations struck 
were the Iowan and Kansan drift with forest bed between. A 
number of years later a town well was dug at Postville. In dig- 
ging, the same yellow and blue boulder clay formations with forest 
bed between were encountered. We can not give even approxi- 
mately the thickness of the two beds of till, but the forest bed must 
have been quite thick as a wagon load of black earth and decayed 
wood was thrown out but no large pieces were found. 
In later years hogs rooting at a springy place on the hillside 
about 80 rods north of the well first mentioned, exposed clay with 
small boulders. 
Eighty rods southeast of the same well, in a slough, the top of 
a large granite boulder, 2 feet across, is exposed. Three-quarters 
of a mile southeast in the ditch by the roadside 10 or 12 feet of 
yellow boulder clay is exposed, and at a quarter of a mile further 
