Lansing Pleistocene Geology. — JJ^incheH. 289 
continued since the spreading of the lovvan glaciation ; but 
since Wisconsin glaciation the normal action of the river and 
of the creek has not risen above its present plane of effective- 
ness and never higher, even in greatest flood-stage, than the 
floor of the tunnel. The date of burial, therefore, is to be de- 
termined approximately by the length of time elapsed since the 
spreading of the lowan loess, which, compared with the age 
of the K'ansan drift seen scantily spread on the highlands was 
an event much nearer the end than the commencement of the 
Glacial period. 
What events may have taken place after the spreading of 
the lowan loess, during the period of surface degradation an- 
terior to Wisconsin glaciation, it is not necessary, at the pres- 
ent time, to enquire, although they may have been competent, 
perhaps under some such process as urged by professor Cham- 
berlin, in covering these remains where they were found. That 
would make their burial pre-Wisconsin and post-Iowan. 
Concise statement of the tioo -views. 
Professor Chamberlin's interpretation of the facts requires: 
1. A floodplain built by the united action of the creek, the 
river, and the wash from the adjoining bluffs, in post-Wis- 
consin time, thirty-two feet more or less above the present 
floodplain. 
2. In order to that, the interpretation assumes that the 
river flowed, in post-Wisconsin time, at low water stage at 18 
feet above the present floodplain, and eroded the shale over- 
lying the rock constituting the floor of the tunnel. 
3. It reqiiires a heterogeneous mixture of floodplain com- 
position, made by the agents specified, rising from the floor of 
the tunnel to the top of "the little relic-bearing deposit," such 
deposit being different in date, origin and composition from 
the lowan loess covering the uplands adjacent, and about 
twenty feet thick. 
Those three points comprise the essentials in his theory, 
all other attendants being of the class of academic statements 
or intended to establish these three. 
The writer's explanation requires : 
I. The identity of the bulk of "the little relic-bearing de- 
posit" with the Towan loess of the region. 
