Topography of Hoivard Co., la. — Calvin. 375 
CONCRETE EXAMPLES FROM THE TOPOGRAPHY 
OF HOWARD CO., IOWA. 
By S. Calvin, Iowa City, la. 
PLATE XXVir. 
With reference to the distribution of geological formations, 
the location of Howard county, Iowa, is one of unusual inter- 
est. Along the Upper, Iowa, or Oneota river, in Alb-ion town- 
ship, the county possesses, topographically, some of the char- 
acteristics of the Driftless Area, an area from which it is sep- 
arated by a comparatively narrow- marginal zone of Kansan 
drift. The margin of the lowan drift passes through the north- 
eastern part of the county, and so northeast of a certain def- 
inite line which can be easily traced, the country is rolling 
Kansan drift covered with loess ; while by far the larger part 
of the county — the part lying southwest of the line referred 
to — belongs to the level or gently undulating, uneroded, loess- 
less lowan plain. One of the interesting geological features 
of this region is the absence of the Niagara limestone or any 
representative of the Silurian system, for here the Devonian 
overlaps upon the shales and shaly limestones of the Ordovic- 
ian. But it is with the topography of the county that this pa- 
per will specifically deal. 
What Norton calls the loess margin or loess moraine of the 
lowan drift passes through the northeast part of Howard and 
divides the county into two very distinct topographic areas, 
each of which is again divided into smaller areas according 
to the extent to which glacial deposits are developed. The 
line separating the two principal areas passes from Minnesota 
into Iowa near the northwest corner of section 11, Forest City 
township, from which point it bends to the west and then turns 
nearly due south, traversing the eastern edge of section 10. 
After passing into section 15 the line makes an abrupt bend 
to the east, passes through the northern part of section 14, 
whence, veering southward, it maintains, with some minor de- 
flections and sinuosities, a general southeasternly course until 
it leaves the county a few rods south of the northeast corner of 
section 36, Albion township. The area north and east of this 
line is comparatively small ; only about 22 square miles, all 
told, are here included ; but within this limited space there is 
