Stevenson.]

THE RIVER TERRACES.

[Aug. 15,

The river terraces fall down stream and are covered by irregularly bedded sand, clay or gravel, containing transported fragments which have been rounded by the action of running water. When followed up the streams these terraces show differences among themselves in degree of slope, so that each is merged successively into the next higher, until that, which at the mouth of the stream is the river "bottom," becomes the only terrace and is lost at last in one of the lower horizontal benches.

For the most part the terraces occur at the same elevation on both sides of the stream, being divided by the channel-way just as the present "bottom" is divided. Sometimes a single terrace and occasionally the whole series of terraces is wanting on one side of the stream. In such a case it is clear enough that erosion was confined to one side so as to remove all traces of the terrace or to prevent the formation of the terraces, just as is seen in the present channel-way, the "bottom" being present often on only one side while stratified rocks reach to the water's edge on the opposite side.

As stated in my report on the Greene and Washington district of Pennsylvania (1875), these terraces are merely shelves in the rock, on which a thin coat of detritus rests. Mr. G. K. Gilbert, in his Memoir on the Geology of the Henry Mountains, describes the occurrence of similar terraces in those mountains.*

These terraces then do not fall in the same category with those described by Dr. Hitchcock in his "Illustrations of Surface Geology," for those had been eroded from valleys previously filled by gravels. No evidence has been found suggesting that any valleys of that sort exist in the region under consideration, while there is good reason for believing that the valleys lined by the river terraces, described in this paper, were not in existence to be filled with gravels.

The terraces below Pittsburgh on the Ohio river are covered by a deposit consisting largely of northern drift brought down by the Alleghany and Beaver rivers. No such material is found along the Monongahela and other rivers south from the Ohio, as they flow altogether beyond the southern limits of the drift. But their age is as clearly shown as is that of the terraces on the Ohio. The fifth terrace, at New Geneva, on the Monongahela, has a layer known as the "Swamp Clay," which contains much halfrotted wood. With the wood are berries like those of the black haw and in the same clay a well-preserved acorn cupule was found. In the same vicinity, as well as near Morgantown in West Virginia, the third terrace shows many Unio shells in an advanced stage of decay, while at Belvernon, on the Monongahela, much wood is found on this terrace. That the third terrace is older than the second and that this is older than the river

*This work has not been published at the time of writing, but Mr. Gilbert has very kindly given me a set of plate files for use during the preparation of this paper. It contains an elaborate discussion of the whole subject of land sculpture, embracing the results obtained by Mr. Gilbert during his long study of the Colorado Plateau.

bottom," is sufficiently proved by the condition of the Unio shells on the several terraces. For those on the first are fresher than those on the second, and those on the second are fresher than those on the third; while the species on all are apparently the same with those now existing in the river.

Since the deposits on the first, second, third and fifth terraces are distinctly of recent origin, there would seem to be good reason for supposing that the valleys below the highest of the terraces are also of recent origin. It has been suggested, however, that the terraces resulted only from reworking of the sides of valleys which had been digged out previously. But this suggestion seems to be hardly in accord with the facts.

It must be remembered that the streams flow on a rock bottom, so that the beds are now at the lowest point ever reached by them; that there is no evidence thus far, going to show that any gravel deposits ever existed along the Monongahela, so as to make its valley like that of the Ohio at Wheeling or Steubenville; that the deposits on the terrace shelves are not remains of valley gravels, but simply accumulations of material brought down by the streams and distributed as the matter has been distributed on the present bottom." Rocky banks are shown at the mouths of tributary streams. Had the valley been filled by gravels, it is incredible that even the most comprehensive erosion could have failed to leave some trace of their exist

ence.

The structure of the valleys below the highest terrace is very different from that observed above it; for in the upper portion the sides are gently sloping, whereas below the highest terrace they become steep almost at once. Above the line of that terrace, the valleys of the smaller streams are broad swales, with smooth sides, while below that line the streams usually flow in gorges. The abruptness of this transition from gentle to abrupt walls shows that erosion had been long at work on the upper part of the valleys and that it began in the lower part at a comparatively recent period; in other words, that the lower portion was eroded after the upper portion had acquired its present form.

The river terraces are relics of river beds, such are the present “bottom;" and the valleys below the line of the highest river terrace have been eroded since the drainage system was re-established by withdrawal of the submerging flood to below the line of the former stream beds.

CONCLUSIONS.

The general conclusions which seem to flow readily from the facts recorded are :

First. That the erosion, to which is due the general configuration of the surface above the line of the highest river terrace, began even before the elevation of the anticlinal axes and continued until the region was submerged in post-glacial time.

Second. That the horizontal benches are due to the re-working of pre-existing valleys, and that they mark stages of rest during the emergence of the continent from the submerging flood.

Third. That the river terraces and the valleys, which they line, were formed after the drainage system had been re-established by withdrawal of the water to a level below that at which the streams had previously flowed. It will be seen that the last conclusion leads to one of wider application. So long time had elapsed between the beginning of this drainage and the coming of the great flood, that deepening of the water-ways had become not more rapid than the general wasting of the adjacent country; for we find comparatively gentle slopes down to the line of the highest river terBut after the drainage had been re-established, the rate of flow must have been more rapid than before, so as to increase the corrasive power of the streams to far beyond what it had been, for in the newer parts of the valleys the sides are abrupt. There must, therefore, have been a change of altitude with respect to tide-level, to lead to this increased rate of flow and the consequent increased speed with which the channel-ways were deepened.

race.

It would appear then, that, after the submergence following the glacial period, the continent rose to a greater height than it had before the submergence, or that the ocean was drawn off to a lower level than before; the result in either case being the same-to depress the mouths of the great rivers, to increase the fall of the streams, and therefore to cause the deepening of the channel-ways.

The Philosophy of the Biblical Account of Creation.

By Aug. R. Grote, A. M.

(Read before the American Philosophical Society, September 19, 1879.) Mr. Grote introduced his subject with a list of works which he had consulted, by the following authors: Keil, Kuenen, Colenso, Bleek, Sharpe, Haverick, Geiger, Goldziher, Geo. Smith, Delitzsch, Cory, H. C. Rawlinson, Geo. Rawlinson, Von Herder, Arnold, Spiegel, Simrock, Max Müller, and Prof. Adolf Duschak.

He then gave in brief the historical distribution of the Shemitic languages and their literary remains; following this with the Hebrew text (in English letters) of the first two chapters of Genesis, and in opposite columns his own translation, with that of the authorized English version in parenthesis, thus:

20. Vayyomer Elohim Yishr'tzu hammayim sheretz nefesh chayyah v'of y'ofef alla aretz, al p'nay rakeeah hashamayim.*

20. And Elohim (God) said: Let the waters abound with (bring forth abundantly) creeping (the moving) creature living (that hath life) and fowl shall fly (that may fly) above the earth in the face (in the open) of the expanse (firmament) of hea

ven.

*Syntactically the word "v'of" (and fowl) besides being the subject of "y'ofer" (shall fly) may be the object of “Yishr'tzu" (abound with). The common English version gives it exclusively as the object, and supposes a relative pronoun understood.

1879.]

[Grote.

And to this verse he drew special attention, subsequently, as showing that in the Elohistic Genesis the fowls were described as created out of the waters; whereas in the Jehovistic Genesis (2:19) it is said:

Vayyitzer Yahveh Elohim min ha-Adamah kol chayyath hassadaih v’aith kol of kashshamayim vayyabhai el ha-adam, &c.

And out of the ground Yahveh Elohim (the Lord God) formed every beast of the field and every fowl of the heaven (air) and brought (them) before the man (unto Adam), &c.

The "literary criticism" with which the author follows these chapters discusses the evident distinctness of the two narratives.

They differ in almost every particular, in the arrangement, in the facts, in the name of the Deity, in their object, and lastly, in the language used. The different arrangements of the two accounts need hardly be pointed out.

"In the first account we have an orderly progression, a subdivision of the whole drama into acts. After each act, occupying a day, the curtain drops; the work must have been done in the night, as the day begins with the evening, although we are somewhat puzzled to understand how the author could have imagined 'evening and morning' before the creation of the sun.

"The second account, on the other hand, beginning Ch. II, 4, has no division of time at all, nor is there an orderly subdivision of events; all events are only told with reference to one central fact, the creation of man. A comparison of the facts narrated in each shows the following differences:

"The first account begins with Chaos, as in the Greek Cosmogony, the first differentiation being between light and darkness on the first day. The second day brings about the division between heaven and earth. On the third, land appears.

"The second account opens with the earth as a dry arid plain without vegetation and animal life.

In the first account the earth is made to produce the herbs bearing seed and the trees bearing fruit with sced, independently of rain and human interference.

"In the second account the herb of the field does not grow until it has rained and man has tilled the ground, though we are not told whence he obtained the seed to plant, nor how the uncultivated plants originated. Man, however, appears first on the ground, while in the first account he is the last object of creation. In this act itself a variety of divergencies may be noted.

"In the first account man is made in the image of Elohim, in the second no mention is made of his "god-likeness," on the contrary we find that it was quite against the will of the Deity that he should become so. And after he had become so by the advice of the serpent and the curiosity of Eve, he PROC. AMER. PHILOS. SOC. XVIII. 104. 20.

PRINTED NOV. 5, 1879.

is driven from the Garden of Eden for, says Yahveh Elohim (Ch. III, 22), 'Behold the man has become like one of us to know good and evil," exactly as the serpent had foretold in the same chapter (verse 5): "for Elohim knows that on the day of your eating therefrom, your eyes will be opened and you will be like Elohim knowing good and evil.

"In Chap. II, 27, man is created, male and female.

"In the second account woman appears only after a surgical operation. "In the first account the birds appear on the fifth day, the wild beast and domesticated cattle at the beginning of the sixth day, after which follows the creation of man, male and female.

"In the second account Adam is first made alone, in a manner to which we find no reference in the first account. Then the beast of the field and the fowls of the Heaven' are made by Yahveh Elohim from the ground before woman is created. Mark also, that first beasts and then fowls are

made by Yahveh Elohim himself, out of the ground, in the same way as Man; but in the first account the fowls are produced, at command on the fifth day, out of the water, and beast and cattle are brought forth by the earth on the sixth day.

"The first account knows nothing of the Garden of Eden, of the four rivers, of forbidden fruit, of the naming process and of matrimony.

"The second does not mention the creation of heavenly bodies, of the fishes and whales,' and of creeping things. It knows nothing of 'festive seasons' and of the Sabbath.

"In the first account Man is given unlimited control over the whole earth and all animal creation; in the second he is simply the gardener of Eden."

He next discusses the difference between Elohim and Yahveh Elohim as names for the Creator, and infers that the first account was penned by an Ephraimite, and the second by a Levite, who omitted mention of the Sabbath because the Levitic tendency was to refer all festivals to the Exodus, the Sabbath included (see Deut. 5: 15); whereas the Elohistic Sabbath was an adaptation from the planetary (Saturn) worship of pre-Levitic times. "The Hebrews were undoubtedly Zabeans in the early stages of their development; in evidence of which we have the word Shabbah, to swear, from Shebbah, seven; i. e., swearing meant to call the seven stars or gods to witness. We find Amos (5: 26) reproaching them with worship of Keeyun, Saturn."

"The Yahvistic account has a different object in view. When it was committed to writing the priestly dominion must have been already very pronounced." "We hear Yahveh declare (6: 5) that the wickedness of man was great on the earth, and the instinct of the imaginations of his heart was only evil day by day." "Cain and Abel bring sacrifices" (4: 3,4). "In the history of Noah we find the distinction of clean and unclean beasts."

"From the geographical notices (v. 10, 14) we may learn that the trade