24 JOURNAL AND PROCEEDINGS 



4. The Medina Shale. 



In a direction N. 20° E. from this exposure, eleven feet in ver- 

 tical height lower and six hundred feet in horizontal distance, we 

 have : — 



1. Red and green sandy clays with a few Hudson River bould- 

 ers — 3 feet 1 1 inches. 



2. Reddish-brown clay impregnated with sodium sulphate--! 

 foot. 



Following the strike of this bed for forty feet six inches in a 

 direction N. 60° W. we reach a stretch of sixty-two feet, measures 

 concealed, then an outcrop of reddish clay, averaging from three to 

 four feet, in a direction N. 40° E., then, at a distance of one- 

 sixteenth of a mile north of the second outcrop, on a section striking 

 N. 40° E. for seventy-two feet, we have in descending order : — 



1. Red-brown sandy clay— 3 feet 2 inches. 



2. Red-brown clay with pebbles — 4 feet. 



3. Red-brown clay, strongly impregnated with calcium chloride, 

 intersected by joints N. 60" E. and N. 41° W. — 4 feet. 



This last outcrop lies about twenty-three feet below the first, 

 showing thus a small dip towards the lake. 



Except for the presence of sodium sulphate and of calcium 

 chloride, the foregomg may be taken as a fairly typical section, as 

 has been already stated, and from the point last mentioned about a 

 quarter of a mile of lacustrine sand overlies the clay as far as the 

 lake shore. On the lake shore the banks are composed of brown 

 clay, stratified yet unfossiliferous, capped with sand. It may be 

 here added, too, that about a quarter of a mile of sand and clay 

 beds has been, within the last fifty years, washed into the lake — 

 that the lake margin then was nearly a quarter of a mile seaward 

 from the present position. But this account is merely traditional, 

 and must be received as such ; and a far more interesting fact 

 awaits us on turning our looks towards the land. For about fifty feet 

 above the lake and about a mile and a-quarter south of the present 

 margin, there extends a true boulder pavement — a ridge of boulders 

 or " field stones," rising about three to six feet above the general 

 level, parallel to the present lake margin. Its material has evidently 

 been derived from a lake terrace, to be noted immediately. It is 

 distinctly stratified and corresponds to Burlington Beach of to-day. 

 It is worthy of note that the deposits to the south of the boulder 



