As we contemplate the inescapable significance of the many complex and thick sequences of sedimentary rock layers on the earth, we must take special note of one fundamental problem in all "Flood geology" explanations of the strata. Those who have set forth such attempted explanations have, without exception, failed to take into consideration the processes which are absolutely necessary in the conversion of sediments into hard, indurated* rock.

1. Misconceptions of Far-reaching Proportions

To the best of my knowledge, all such authors assume either (a) that the lithification of sediments is a simple process similar to the baking of brick or the hardening of concrete, or (b) that, if the process is more elaborate than that, some unknown provisions must have existed by which the steps in lithification could have been accomplished during the short time since the flood. The latter group invariably fails to face the problem of how soft sediments could remain amassed together in vertical sequences even several miles thick without either amalgamating the many thin layers or crushing the fossils—and without literally flowing off the high elevations into the low ones. Everyone who stands looking at even a road bank of hundreds of repeating alternations of shale and sandstone, or of shale and limestone, should contemplate the significance of the fact that these remained distinct after their deposition. Then they should go to a State Geological Survey Office and examine deep-well cores of similar sets of layers which are also distinct, even though they are from 2 to 5 miles deep in the subsurface. Obviously, these had to be strongly cemented* before the enormous weight of the overburden was added, and before the tectonic adjustments of position occurred.

2. Rock Cementation Processes

We must face not only the fact that the lower parts of the sedimentary cover had to be lithified before the upper were deposited, but also that the lithification of practically all kinds of sedimentary rock is of necessity a slow change—slow because of the very nature of the several processes involved. None of the proposals that the sedimentary rock strata of the earth could have been formed rapidly are based upon scientific observations. On the contrary, these proposals ignore the whole field of sedimentary rock petrology and the thousands of careful scientific observations which it has recorded. Some of the creationist leaders have made a few scientific observations of how sediments can be moved and re-deposited by water in local floods. But observing the moving of sediments is a far cry from making scientific observations on how the many types of rock layers are deposited and have actually lithified.

In the case of igneous* rocks the crystalline structure which binds the particles together is formed as molten rock material cools and solidifies. But in the formation of most sedimentary rock types, already-solidified particles are the basic raw material, and these must be cemented together by the precipitation of layers of minute crystals around the solid particles. The substances for forming these delicate microlayers of crystals have to be carried by circulating water, in ionic form, to the surfaces of the sediment grains. The most common cementing substances which are thus carried and precipitated are calcium carbonate, silicon dioxide, and various types of iron oxide. It is possible for extremely fine-grained sediments such as clay to be indurated to a considerable extent without much cementation as a result of the establishing of attractive forces between the closely fitting particles when compaction takes place (Blatt, et al., 1972, p. 353). This has often resulted in the formation of layers of shale. But unless the shales are either heated hot enough to become slate or cemented at some later time, they remain soft enough to be broken between one's fingers—as is true of at least most of the vast bodies of shale which we find in the Devonian through Pennsylvanian strata systems in the Appalachian Region. (Thick sequences of shales similar to these are found in most of the great geosynclinal areas of the earth.) In formations which have layers of sandstone alternating with the layers of shale, the sandstone became strongly cemented because water could circulate horizontally through it. But since oniy small amounts of water could pass between the particles of the shale, oniy a weak cementation could develop in it.

To come back a moment to the popular idea that if bricks and concrete can become hard in a short time, then perhaps layers of naturally-deposited sediments could have lithified rapidly, we point out the following. First, the binding materials which hold the particles of a brick or a block of concrete together are entirelydifferent in arrangement from those which hold limestones, quartz sandstones and siltstones together. If we make a standard thin-section* of a brick or piece of concrete for microscopic observation, we find nothingsimilar to the rows upon rows of calcite crystals that are in a thin-section of limestone, or of silicon dioxide crystals in sandstone or sihstone. The section of limestone will usually show a few to several known typesof crystals, according to the physical conditions under which the crystals were formed—a great contrast to the monotonous, hastily-formed binding substance of concrete. (For photomicrographs of several types of cementing crystals actually in place in the limestone where they were formed, see Scholle, 1978, pp. 160-167.)

We also need to contrast the splendid durability and almost indestructible nature of many sedimentary rocks with lack of durability of bricks and concrete. Some bricks and carefully made concrete may last for 50 years before crumbling. But slabs of hard, quartz sandstone used by man for monument stones have stood in the weather for hundreds of years without appreciable wear or damage. Sandstone of this quality is very abundant in the sedimentary cover of the earth, and exposed strata of it are used extensively in most countries of the world.

Some persons might be tempted to say that the sedimentary petrologists only know about cementation from looking at thin-sections, and not from observing actual cementation processes. This is not at all the case, however. In many parts of the world, sedimentologists are now observing and taking samples of rock in various stages of lithification. These samples come from shallow sea floors, coral reefs, lake bottoms, caves, and other places where stationary sediments are being permeated by water flowing through the pores of the sediment mass. Also we have access to many different bodies of sediment, e.g., Pleistocene carbonate sand accumulations, which show varying degrees of cementation, depending on how well they have been supplied with the necessary mineral ions for forming the cement crystals. Thus the production of rock from sediments has been observed to be a dynamic, ongoing, and orderly process which involves many sequential steps.

3. Methods and Rates of Rock Cementation

Mention has already been made of the precipitation of cement crystals between the particles or grains of sediment in sedimentary rocks. This precipitation is dependent upon the transport of the necessary ions of the precipitating mineral by water percolating through the sediment mass. In order for the process of cement formation to proceed, the pore water passing through the sediments must not only contain the right kinds of ions, but the concentration of those ions must be sufficiently high for precipitation of the cementing mineral (usually calcium carbonate or silicon dioxide) to occur. This precipitation of cement crystals must occur in an orderly manner onthe surfaces of the mineral grains—a process which does require substantial amounts of time. This is especially true for hard limestone and dolostone, where frequently 50% of the composition is the cement crystals themselves (Friedman and Sanders, 1978, pp. 147-148). Thus the enormous amount of mineral which has to be carried in solutionin order to complete the cementation process demands considerable periods of time, and favorable conditions for cement precipitation have to continue throughout these time periods. The concentrations of several kinds of ions, as well as other factors such as temperature and pressure, must remain at the proper levels, or precipitation of the cement crystals will not take place.

Many detailed studies of both present-day and ancient cementation have been made. It has long been known that carbonate sands lying at the surface on tropical beaches can sometimes be cemented into hard rock within a mere few years. However, the resulting "beachrock" is readily identifiable microscopically because of the distinctive types of fibrous and micritic* cement within in. Only a small percentage of ancient limestones show these types and arrangement of cement or other distinctive characteristics of beachrock, so we know that the formation of beachrock was very limited. The formation and occurrence of beachrock on many coasts has been known for over a century, though the precise conditions for its production are only now being learned. The formation of this type of rock is almost entirely restricted to the warm climatic belts of the earth, and occurs only at very shallow depthson the beach. Friedman (1975, p. 389) states,

The exact means by which this water is brought to the necessary supersaturated state, and precipitation of the beachrock cement induced, have not yet been discovered with certainty. Friedman (1975, p. 389) states that the precipitation is likely due, to supersaturation caused by periodic evaporation of water near the surface of the accumulated sediments. J. S. Hanor (1978) made a detailed study of beachrock formation in the Virgin Islands and concluded that the precipitation of beachrock cement is induced mainly by the loss of dissolved carbon dioxide gas from the water present in the pores of the carbonate sediment. The solubility of CaCO3 in the pore water is governed in part by the amount of dissolved CO2 gas. The periodic loss of CO2 gas decreases the CaCO3 solubility, and the precipitation of calcium carbonate cement ensues.

The main point for us to note regarding these events is that in any casethe precipitation of beachrock cement is dependent upon chemical processes which are maintained only at or very near the surface of the shore sediments. Thus we must not expect to find rapid formation of cement taking place after sediments become deeply buried. For this reason no "Flood geology" proposal, that great thicknesses of sediments were deposited during the Flood and then rapidly cemented, can find support in the process of beachrock formation.

Carbonate sediments which have been buried to an appreciable depth are lithified by a set of controlling factors different from those which cement beachrock. Bathurst and others have determined the approximate rate of normal cementation of thick masses of buried carbonate sediments found beneath beaches in semi-tropical latitudes. From these known cementation rates they have calculated that 80,000 to 90,000 years are necessary for normal filling in of the spaces between the sediment grains in a deposit of carbonate sediment 10 meters thick if the deposit is receiving a constant flow of ion- bearing water from top to bottom of the mass (Bathurst, 1975, pp. 439-441; 1983, pp. 355, 367-369). That means that 80,000 years are required, under very goodcementation conditions, to convert a 10-meter deposit of sediment into hard limestone. Notice here that this is a thickness of sediment through which a continuous flow of water can conceivably be maintained, without its being subjected to an early sealing off from percolating seawater by clay-sized sediment. Thus, while the upper 10 meters of sediment are receiving a good flow of water between the grains, the sediment which is deeper down below that particular deposit will likely receive an inadequate flow most of the time.

4. Postulating an Unnatural "Plumbing System"

An understanding of some of the principles of cementation such as the above will cause us to realize that young-earth creationists have been completely unrealistic in proposing that the great thicknesses of sedimentary cover of the earth were formed rapidly, only a few thousand years ago. Even if one could surmount the problem of how rapidly-amassed sediment layers could have been maintained as distinct, without amalgamating into one another and without crushing the fossils and various ephemeral sedimentary structures, the great problem of cementation would remain. How could the vast expanses of thousands of square miles of sedimentary layers, often piled 3 to 5 miles deep, receive the proper flowof pore water for cementation—especially if the cementation were to be accomplished in a minute fraction of the normal time? We are not asking how all of that sediment could be rapidly cemented into one solidmass—though even that would require a supply of pore water too elaborate to contemplate. Instead we are faced with the fact that practically any area of sedimentary cover with a thickness such as this—as in the Appalachian Region—contains an orderly sequence of many distinct typesof cemented rock layers. When one considers the entire vertical column at any point, such as in West Virginia or central Pennsylvania, he finds hundreds of changes in rock type per mile of thickness. Each of these rock units usually extends for some miles horizon tally in all directions, and samples of these layers are readily correlated from different deep wells drilled within a large radius.

This means that each type of rock layer—whether it be sandstone, siltstone, graywacke, or one of the different types of limestone—during the time it was being cemented, had to be receiving its own properkind of ion-bearing pore water. And this supply of special pore water had to be furnished to the sediment layer over a wide areal extent.This is possible so long as there is a large body of water nearby and the burial depth of the sediments being supplied with pore water is not great. Then there is the fact that quartz sandstones are nearly always cemented by pore water rich in silica (rather than calcium carbonate), resulting in the formation of silicon dioxide cement crystals, whereas limestones are practically always cemented with crystals of calcium carbonate or dolomite. This is no problem so long as the cementation is occurring in a near-surface location, with water passing over or near the sediment mass. But how can one logically postulate some sort of unimaginably elaborate "plumbing system" which would have supplied each of the deeply-buried layers, over all those thousands of square miles, with the types and amountsof pore water needed for rapidly cementing them into distinct types of rock?

One cannot solve this problem by saying that the water was circulating vertically up or down through all the sediment beds (even if such were possible through 3 to 5 miles of sediment) and that the quartz sand and silt layers were cemented with silica* ions from their own grains, and the carbonate layers with calcium, magnesium and carbonate ions from theirs. The fact is that we regularly find such distinctly different layers in direct contactwith each other, each with its own kind of cement. If the flow of water had been passing from one type of layer into the next above or below, there would have been an intermingling of cement-types throughout the column. Also, it is necessary to face the fact that the physical conditions for silica cementation are very different from those for carbonate cementation. There seems to be no way the two sets of physical conditions could have been maintained adjacent to one another in alternating, repeating, and often thinlayers. The only really logical conclusion concerning the formation of such strata is that the limestone layers achieved their original primary cementation while they were within reach of the type of pore water they needed, and that the sandstones and siltstones were cemented at a time when a non-carbonate-producing environment was prevailing in the area.

Postulating rapid cementation due to a supply of mineral-laden water from hydrothermal springs or volcanoes, as some creationists have done, is also futile. Such localized sources could not provide a horizontally-moving, uniform supply of the needed kinds of ions (or even of pure water) to produce the distribution of cement we find in these 3 to 5 mile columns of layers. Young-earth creationists hypothesize that all of that cementation has occurred in the short time since the Flood, but both the necessarily-slow character of the process and the insuperable problem of distribution of the proper kinds of ionic solutions makes this impossible. The difficulty of fluids from hydrothermal springs providing a uniform and rapid supply of ion-bearing water to far-away sediments is further complicated by the presence of many hundreds of layers of tightly compacted clay (now shale and claystone). These, being distributed throughout much of the 3 to 5 mile-thick mass of sediments, would have almost completely blocked vertical movement of water to strata above or below.

In thinking about the origin of the thousands of orderly strata in such a sedimen tary column, we need to realize that there is a pronounced lateral uniformity of layers over broad areas. This uniformity is of course not always a uniformity of thicknessfrom one mile to the next, but it usually is an impressive uniformity of cement type, grain type, and chemical composition. And most cement types are those of natural marine or fresh water cementation, rather than types produced under the influence of volcanic brines.

Catastrophist creationists who learn of these problems are invariably thrown into a confused set of speculations in attempting to explain them, advocating hypotheses for which they have no relevant observed data. For example, they cannot cite even one cubic kilometer of limestone and sandstone sequences which have been cemented by circulation from hydrothermal springs or other rapid means. Furthermore, such explanations will never work, since fluids from hydrothermal springs and volcanoes could not produce cementation of the marine and fresh-water types, even if there were some way for them to be evenly distributed to the sediment layers. We should remember that God has never asked us to defend his truth with irrational explanations, or by postulating processes which contradict or violate the natural laws He has created.