HAYES AND 
KENNEDY. 
CHANGES OF LEVEL. 67 
This sinking appears to have been accompanied with a series of 
oscillations or tilting of the land, and it was probably during this 
period that a considerable part of the flexing or faulting of the beds 
which resulted in the formation of the anticlines, or lines of dome- 
shaped elevations, took place. 
Again the sea began to recede, and the Columbia sands were raised 
above the level of the water. High-level conditions again prevailed, 
and there followed a period of nearly stationary conditions with only 
a few slight oscillations. The flexing or folding that was active in the 
preceding period evidently continued through this also, and the domes 
were raised still higher, until probably their crests approached the 
surface of the water and formed reefs and islands occupied by such 
marine shallow-water life as the Ostrea. 
The land subsequently tilted seaward, and it was during this time 
that the disposition of the Beaumont clays took place. These clays 
and muddy deposits associated with them were evidently laid down 
in water comparatively shallow and subject to prolonged periods of 
alternate marsh and lake conditions. They are very generally filled 
with stumps and logs, and at a depth of from 45 to 100 feet appear to 
have had a period of vicissitudes very closely approaching those to 
which the overflow bottom lands of many of the present rivers are 
subject. Marshy conditions doubtless occurred, and during that time 
the cypress appears to have flourished. Floods brought down from 
the higher grounds the dead and fallen wood and other debris, and 
the small streams and rivers, upon entering the comparatively quiet 
waters covering these flats, dropped their burdens, which were after- 
wards assorted and distributed by the tide. 
A further slight rise took place and these clays became dry land, 
and the shore line was moved much farther southward, until it prob- 
ably stood about where the Trinity shoals are now situated. The 
final change followed this elevation and present conditions were 
inaugurated; the sea again began to encroach slowly upon the land, 
which it appears to be doing at the present time, at least in the region 
eastward of the Trinity, though west of that river the land is slowly 
rising. 
It appears that the area between the Brazos and Guadalupe rivers 
was less affected by these changes of level, and that even in Lafayette 
times this area formed a ridge extending seaward, and that through- 
out all the fluctuations it maintained a comparatively higher altitude 
than the regions on either side. 
Evidence pointing to the same conclusion is the presence of beds 
belonging to the Miocene and earl}'- Pliocene at the surface through- 
out several portions of the margin of the western Coastal Plain, while 
these beds do not appear anywhere throughout the eastern end, but 
lie buried to a depth of several hundred feet. 
