[[underline]] 1892 [[/underline]] 
[[underline]] December 5. - Continued [[/underline]] 
rest of the exposures show only Columbia brick clay, and this is also the 
case with all between here and the White House Bluff proper, which 
begins just west of the extreme easterly point of land on this neck. 
Here the Potomac suddenly rises up with first only the Columbia, but 
soon with a heavy bed of Marine Tertiary, mostly Chesapeake overlying 
it. The boundary between this latter and the Potomac has furnished one 
of the most difficult problems I have encountered. The entire extent of 
the Potomac along the shore above this point is less than half a mile, 
and it terminates as abruptly as it begins immediately above the original 
plant bed of Prof. Fontaine Midway of its extent there is a log-slide, and 
the bluff has here reached a height of some 70 or 75 feet. The white 
kaolinic sand rock at the base is here hardened into free-stone, less firm 
than but generally similar to that of Aquia Cr. and Point of Rocks. The 
following is a section at and below the log-slide: 
[[end page]] 
[[start page]] 
[[three columns, indicated in transcription by |]] 
6 | Columbia brick clay | 6 feet 
5 j " [[Ditto for: Columbia]] gravel and cobble | 5 " [[Ditto for: feet]] 
4 j Clay, light colored weathering red or mottled, and cracking into small 
square blocks, greenish and less broken below, clearly Chesapeake | 4 
" [[Ditto for: feet]] 
3 | Coarse orfirmish stratified and cross-bedded sands, yellow, brown, 
gray, blueish, or jet black, with thin sheets of ferruginous rock or shale, 
sometimes 
tending towards concretions and rarely 
horizontal, with many green clayey pellets, pockets, lenses, or strata, 
the 
latter sometimes reduced to lines of fine lumps | 3 " [[Ditto for: feet]] 
2 | Coarse sand with less inclusions, but otherwise not distinguishable 
from No. 3 | 10 " [[Ditto for: feet]] 
1 | Coarse kaolinic white lithified sand or 
freestone rock with clay balls, lenses 
&c., some of them green and glauconitic, also rounded quartz pebbles | 
20 " [[Ditto for: feet]] 
[[line indicating addition]] 
Total 75 " [[Ditto for: feet]] 
Local field note-book of Lester Ward 
Transcribed and Reviewed by Digital Volunteers 
Extracted Oct-11-2015 07:35:03 
Smithsonian Institution Transcription Center, Smithsonian Institution Archives 
