Association of American Geologists and Naturalists. 327 
plain. He would ask of Mr. Redfield whether in his opinion 
there was any reason to suppose that the currents in the ocean 
below the surface, always tended towards the equator. 
Mr. Redjfield replied at some length, explaining the geograph- 
ical system of currents observed in the ocean. ‘These were main- 
ly independent of the atmosphere and winds. ‘The whole of the 
evaporation at the equator, let it be as much as it may, would 
have no sensible effect in producing a current from the polar 
regions to supply its place. The Mississippi, through its numer- 
ous branches, received the drainage of many thousands of square 
miles, and some had contended that the influence of its current 
must materially affect the force of the Gulf Stream. He would 
not undertake to say but what some effect was produced, but he 
could say, that it had never yet been perceptible to observation. . 
In reply to a question of Mr. Horsford, Prof- Espy stated that 
the evaporation at the equator could not be the cause of the polar 
currents towards that point. A current of one mile per hour 
would fill up the entire deficiency caused by the evaporation, in 
one hour. It was idle therefore to look to that cause for the 
effect. He thought the mean temperature at the poles and equa- 
tor, a sufficient cause to explain the phenomena of the currents. 
Mr. E. explained this point at some length. The specific grav- 
ity of the water, caused by the difference of temperature, would 
give a current from the poles to the equator. At the equator, the 
temperature of the water at the surface was about 70°, while at 
the depth of one thousand fathoms it was but 37° or 38°, and. 
remained at about that temperature as you went to a greater 
depth. 'This could only be accounted for by supposing that the 
Water at that depth was supplied by a current from the polar 
regions. 7 — . Se pattie 
Mr. Hall read a short paper and presented a natural section of 
& portion of the shore of Lake Erie, exposing the broken and 
contorted strata and intermingled drift. ‘ . 
"This section was exhibited to the Association last year, with a view 
to elicit similar facts and to enable us to draw some inference as to the 
cause producing the phenomena. : : 
_ He stated that the subject of drift had. occupied but a small portion 
of his attention, having been engaged mainly in the study of ‘the older 
rocks and their contents. In the outcropping edges of the limestones 
and other firm strata, he had frequently noticed the separation of the 
layers, one being eleyated at a much higher angle than the next below, 
