24 
Tertiary is if anything more pronounced than in the 
counties to the north. Heavy deposits of altered glau- 
conitic sands, sandstones and laminated ores belonging 
to the marine or Claiborne stage of the Eocene form a 
ridge extending through the centre of the county from 
nearly five miles east of Marshall to beyond the western 
line of the county and for over amile into Gregg, where 
it is separated from the same class of deposits lying fur- 
ther west, by the broad bottom lands. of the Sabine 
River. These deposits are more or less fossiliferous, 
containing the characteristic fauna of the marine beds 
found farther south and west, and rest directly upon the 
uppermost lignitic, exposures of which may be seen 
near Willow Switchin Gregg and at many places north 
and east of Marshall, in Harrison. Laminated and 
nodular ores occur scattered everywhere throughout 
this region. The yellow sand with its contained nodules 
occurs capping many of the secondary portions of the 
ridge and lies intermingled with fragments of laminated 
ore or forms portions of the ore deposits that lie scat- 
tered along the sides and around the base of the ridge. 
There is no use, however, to multiply instances 
in which the two varieties of ore lie associated 
and intermingled with each other. To merely recount 
the localities would be long and tedious and require a 
detailed account of the whole geology and geography 
of the country. 
It must, however, be admitted that as a general rule 
the heavier deposits of nodular ore occupy positions ly- 
ing at relatively lower levels than the heavy deposits of 
laminated ores, and it also appears to be a settled con- 
dition that while extensive deposits of nodular ore over- 
lie these beds, by far the most extensive and valuable 
of these nodular deposits occupy positions between the 
isolated ridges, or what may be said to form the broken 
ends of the marme beds. This, however, is to be ex- 
pected, if we are to assume that these geodes or nodules 
with their surrounding sands are the products, or the 
results of, erosion and consequent destruction of the 
glauconitic beds. That these glauconitic beds extended 
many miles farther north of the positions in which we 
now find the maiz bodies there can be no doubt. Not 
only the points already mentioned, but many others not 
nearly so prominent, still exist, bearing witness to this 
northward extension and the enormous erosion which 
has taken place in the past and is still going on. 
A careful examination of one or two of the most 
prominent of these deposits of nodular ore and the 
yellow and brownish-yellow sand will, I think, be suffi- 
cient to show that these are both the results of the 
degradation of the beds now forming the ridges. Ma- 
croscopically, thissandis the same as the heavy deposits 
found covering many portions of the regions —in 
Cherokee, Rusk and Anderson Counties, in which the 
laminated ores have 
The nodules of ore found among these sands do not 
occur promiscuously scattered over the face of the 
country, but usually occur in pockets or irregular 
deposits and at a noticeably higher elevation than the 
general level of the surrounding country. 
In saying that none of these ore deposits occurs be- 
neath the thinly stratified uppermost lignitic beds, I do 
not mean to affirm that no ore occurs within the lignitic 
series, but simply that none of the great deposits of 
nodular ore in east Texas which have hitherto been 
assigned to that series belongs to the lignitic. Small 
deposits of a nodular variety of ore as well as clay iron- 
stone do occur at several places within the lignitic beds. 
These, however, lie at considerable depths and are 
found amongst the clays and sand of that series in well 
digging and other deep excavations. These are not all 
SCIENCE. 
their greatest development. 
[Vol. XXIII. No. 571 
clay iron-stones nor carbonates, as has been asserted, 
and throughout the extensive areas of the eastern 
division of the State, in which the lignitic strata form 
the surface deposits, no ore of any kind has yet been 
found. The absence of these ores from the great lignitic 
areas of Limestone, Robertson, Smith, Harrison, 
Panola and other counties certainly appears remarkable 
if the nodular ores of Cass, Marion and others belong to 
these deposits. 
While the question of the age of the nodular ores may 
form a subject for discussion, no such doubt or diffi- 
culty besets the age of the laminated ores of the 
region. These are altogether from top to bottom of 
Tertiary age and of the lower Claiborne or marine 
Eocene wherever found. These ores are connected 
with, and form an integral part of, the marine beds, 
and while the heaviest deposits are always, or nearly 
always, found at or near the surface, the same character 
of ore occurs at more than one horizon and lies inter- 
stratified with the glauconitic or greensand beds. 
Borings, as well as numerous natural sections, have 
demonstrated this fact,—and by the same methods it has 
also been shown that these lower beds are always much 
thinner than the upper, or surface deposits. Besides 
being thus stratigraphically constructed with the green- 
sands, the ores themselves are also fossiliferous and 
carry the same fauna as that found in the greensand 
deposits. Numerous specimens gathered from deposits 
both overlying and underlying these ore deposits and 
from the ores themselves are to be seen in the cabinets 
of the Geological Survey of the State. 
Just why these ores should assume the forms in which 
we now find them is somewhat difficult to say. It is 
quite likely that the laminated ores were deposited with 
the glauconitic deposits as bog iron, and part of them, 
particularly the interstratified deposits, have been 
derived from the destruction of the glauconite, and 
again from the destruction of these deposits, through a 
process of solution, infiltration and segregation, the 
nodular ores have been derived. Dr. Hilgard ascribes 
the formation of the nodular ore found in the Orange 
Sand in Mississippi to the solution of the iron contained 
in the sand and its leaching and sinking through that 
deposit and segregation at the base where the solution 
met with an obstruction to its descent in the impervious 
clays of the underlying lignitic beds. If this theory 
holds good for the Mississippi ores it certainly has 
everything in its favor so far as the Texas ores are 
concerned. ‘There is at least one point in favor of such 
a theory everywhere throughout the Texas iron region. 
The waters found in nearly every spring and well in 
the country are highly charged with iron, many of 
them excessively so, and many of the streams crossing 
the ore-bearing ridges contain this impurity to such an 
extent that they are absolutely devoid of animal life. 
The waters of these streams are of a pale amber yellow 
color and excessively astringent taste. 
Dr. Penrose’s theory that these nodules are derived 
from nodules of clay iron-stone found in the underlying 
beds by oxidation—‘‘When the carbonate has been com- 
pletely oxidized the ore is either composed of concen- 
tric layers separated by cavities or is massive on the 
outside and hollow inside, forming geodes or iron pots. 
The clay or ochre often occurring in the geodes. doubt- 
less represents the residual product left after the oxi- 
dation of the impure carbonate’’—does not appear to 
hold good in all cases. Many of the nodules found in 
‘the regions under consideration are not filled with 
residual ochre, but with coarse white and yellow sand, 
having exactly the same texture as that in which the 
nodules lie ; besides some of the nodules found on the 
