December i, 1893.] 



SCIENCE. 



299 



miles in width along the coast, and comprise a series of 

 blue, brown, yellow and variously colored clays, many of 

 which are highly calcareous. 



With probably the exception of the basal beds, which, 

 as has already been stated, appear to be somewhat irregu- 

 larly distributed along the contact between the Tertiary 

 and the underlying Cretaceous, the whole of these depos- 

 its may be considered ag lying in a series of irregular 

 belts roughly parallel to the present coastal line, while a 

 section drawn across them almost anywhere would show 

 each to have an abrupt exposure towards the northwest. 

 In other words, while the dip is approximately southeast, 

 the northwestern edge aiDjjears usually as an escarpment 

 showing the broken ends of the beds, and in places these 

 escarpments have deflected the courses of several of the 

 rivers crossing the Tertiary area. These rivers also appear 

 to be working southward, showing high steep bluffs along 

 their southern sides, while broad fiat bottom lands appear 

 along their northern banks. Such also appears to be the 

 course of operations with all the larger streams running 

 in an easterly or westerly direction. 



A peculiarity noticeable among the lower divisions of 

 these deposits is a flexing or bending of the beds, begin- 

 ning in the lignitic, and, so far as at present known, 

 reaching the culminating j)oint towards the top of the 

 marine beds. This flexing has resulted in making many 

 of the higher hills hills of erosion and the tops portions 

 of the synclines. 



From this brief outline it will be seen that the greater 

 portion of the Tertiary areas is made up of extensive beds 

 of clays and sands. 



The analyses of these clays made by the different chem- 

 ists of the Geological Survey show them to have the 

 peculiarity of having the proportions of the alkalies pot- 

 ash and soda reversed. ' In the greater number of clay 

 analyses which I have had occasion to refer to, the pro- 

 portion or percentage of potash exceeds that of the soda. 

 In the Tertiary clays of Texas the proportions of soda ex- 

 ceed the potash as 3.19 of soda to 1.18 of potash. These 

 proportions vary in the different stages, as will be seen in 

 the following: 



Potash. Soda. 



1. Basal beds, - - - . 



2. Lignitic beds, - - - - 



3. Marine beds, - . . . 



4. Yegua beds, - . . - 



5. Fayette beds, - . . . 



6. Fleming (Freo) beds, no analyses made. 



7. Coastal clays, - . - . 1.56 5_52 



From this it will be seen that there is a gradual decline 

 of the two alkalies as we ascend until the coastal clays are 

 reached, when the soda shows a sudden increase over the 

 basal beds almost equal to the sum of the losses it sus- 

 tains in the other members of the series, while its actual 

 increase over the Fayette beds amounts to 3 55. The pot- 

 ash also shows an increase in these beds over the basal 

 clays of only 0.03, and over the Fayette beds of 0.88, or 

 about equal to the sum of the losses sustained in its 

 course through the deposits from the lignitic to the Fay- 

 ette. 



The question of the origin of these clays involves the 

 existence of an extensive land area of deposits in which 

 the alkalies were strongly represented, and, assuming the 

 solubility of the two to be approximately similar (as a 

 matter of fact the potash is slightly more soluble), one in 

 which the soda was considerably more abundant than the 

 potash. Again, throughout the dejjosits and interbedded 

 wilh the clays we have heavy beds of sand, many of them 

 almost pure quartz, and the greater portion of the clavs 

 themselves are highly silieious. In addition, the immense 

 deposits of limonite found interstratified with and cover- 



ing the marine stage of these deposits will require to be 

 accounted for. 



It appears to me that the most probable immediate 

 sources of the materials entering into the composition of 

 these Tertiary deposits are the underlying cretaceous beds 

 for the lowermost or basal Tertiary, and a partial rework- 

 ing of the older Tertiary with the cretaceous materials for 

 the upijer or newer deposits. These cretaceous marls and 

 marly claj-s corresijond very closely to the Tertiary depos- 

 its, as will be seen from the following analyses: 



100.15 100.04 100.04 



The third column shows the average of the Cretaceous 

 analyses re-calculated without the carbonate of lime and 

 carbonic acid and omitting a portion of the sulphuric 

 acid, which would undoubtedly be lost during the course 

 of erosion and deposition, and which we might expect to 

 find farther to the south among the more recent of the 

 Tertiary deposits as well as in the coastal clays. The per- 

 centages of lime and sulphuric acid shown in this analy- 

 sis are the averages shown in the Tertiary deposits. The 

 course of the lime through the different sets of beds 

 appears to be thus: 



Basal beds, 

 Lignitic beds, 

 Marine beds, 

 Yegua beds, 

 Fayette beds, 



2.05 

 0.77 

 1.97 

 0-43 

 10.75 



Many of these Fayette clays contain as high as 24.42 

 jjer cent of lime and 18.91 per cent of carbonic acid. 

 Among the sandstones belonging to the upper division 

 there are many beds which might be classified as calcare- 

 ous sandstones, some of them containing enough lime to 

 have made it profitable at one time to use them as a 

 source of lime for building purposes. Their derivation 

 from Cretaceous deposits is also indicated by the exist- 

 ence of numerous water- worn Cretaceous shells. 



The coastal clays contain immense quantities of lime at 

 different points, and nothing short of an immense number 

 of analyses could give us anything like a fair average. 

 They have not been included in any of the above analy- 

 ses. 



The basal beds of the Tertiary so strongly resemble the 

 upper and contiguous beds of the Cretaceous in lithologi- 

 cal as well as chemical structure that it is very difficult to 

 tell them apart, and in many portions nothing but a 

 study of the fauna will enable anyone to differentiate the 

 two, and in many places the Tertiary beds contain boul- 

 ders and fragments of Cretaceous limestones containing 

 Cretaceous fossils. 



It would thus appear that the structural conditions of 

 the Basal beds and the Fayette deposits, apart from any 

 chemical evidence whatever, bears out the assumption of 

 these two divisions being derived from the Cretaceous. If 

 we accept Dr. Penrose's theory that the iron ores and 

 glauconite of the marine beds are largely due to the de- 

 struction of the upper glauconitic division or the green- 

 sand of the Cretaceous, and in this theory, from a long 

 period of work among these beds, I am inclined to believe 

 for several reasons — one of which being the close affinity 

 chemically and otherwise of these beds. Then that will in 



