By James L. Erjavec

Copyright © 1996 by James L. Erjavec

(Notes and editing by Stanley V. McDaniel, author of The McDaniel Report)


ABOUT THE AUTHOR: James L. Erjavec has an M.S. in geology from The

University of Arizona, Tucson, Arizona, and a B.S. in geology from The

Cleveland State University, Cleveland, Ohio. He is a geologist and

Computer/Geographic Information System (GIS) Analyst with over 13

years experience in those fields. A specialist in mapping and computer

graphics, he has developed an extensive geomorphic feature map of the

Cydonia region to assist in the establishment of a geologic baseline

for continued studies.

The paper presented below is a shortened form of a longer piece titled

"A Geologic and Geomorphic Investigative Approach to some of the

Enigmatic Cydonia Landforms." It is important to consider Erjavec's

paper in relation to NASA's claim that the debated landforms at

Cydonia have already been subjected to a thorough scientific study.

From Erjavec's discussion it would appear that NASA geomorphologists

who maintain that the debated Cydonian objects are simply a result of

"differential erosion" have not had the last word on this subject and

that there is much to learn. For further information regarding the

longer version of this paper or the accompanying geologic map of the

Cydonia area, write The McDaniel Report, 1055 W. College Ave. #273,

Santa Rosa CA 95401.


NASA's Position Based on Differential Erosion

Broad generalizations by NASA, which have been based in part on

previous geologic studies of the Cydonia region of Mars, have been

inadequate to definitively explain the origins of the varied surface

features of Cydonia. During the development of a geomorphic feature

map of the area of Cydonia bounded approximately by the 40N to 41.5N

degree latitude lines and the 11W to 7W longitude lines (an area

covered by Viking Frames 70A11, 70A12, 70A13, 70A14, 70A15, 35A72 and

35A74), a preliminary study of the landforms has been conducted,

including both anomalous and "ordinary" forms.

The argument that NASA has evidently relied on to debate the anomalous

nature of the morphologies of the Face and other enigmatic Cydonian

landforms is based on the premise that the Martian northern lowland

plains were at one time covered with a kilometer or more of "erodible

sediment." The origin of the landforms has been attributed to a

differential erosion process that removed an overlying cratered

plateau material, leaving a knobby terrain that is a combination of

exhumed remnants of cratered terrain, igneous intrusives or cratered

plateau material (Guest, 1977).

Inasmuch as popular scientific literature appears to have accepted

this view without reservation, it is not uncommon to find references

to Cydonian landforms that typically cite their origins as the

exclusive result of wind erosion (Henbest, 1992) without considering

the validity of the data and assumptions that support such claims.

Differential Erosion not a Likely Cause

But more recent evidence (McGill, 1989) has been provided that refutes

claims that over a kilometer of sediment was eroded from the Martian

northern lowland plains. McGill has used crater dimensional equations

to conclude that only a slight to modest erosion of the northern

lowland plains could have occurred since Noachian times and that at

best, 200 meters of material may have been stripped off the plains.

This is corroborated by Maxwell (1989) who shows that there is little

correlation between the Martian landform dichotomy (northern lowland

plains and southern cratered uplands) and the trends of scarps and

ridges of the landforms.

Cattermole (1992) states that because a series of closely related

geologic events have affected the northern plains (McGill, 1987;

Phillips, 1988; Frey and others, 1988; Wilhelms and Baldwin, 1989) and

because there is a lack of evidence for where the 2 to 3 kilometers of

eroded sediment has been transported, there is little probability that

erosion was the driving mechanism for the lowering event. Instead he

believes that the evidence suggests the lowering of the northern

plains was a result of some (to-date) uncertain internal mechanisms.

This study corroborates the findings of the above-mentioned authors on

the basis of geomorphological and geological analysis of Cydonian

landforms. To start with, the dimorphic distribution of impact craters

between the knobby terrain and cratered plain in this area of Cydonia

weakens support for an extensive pre-plain overburden. The knobby

terrain contains several large impacts greater than 1 km in diameter,

but relatively few craters below this threshold. The pediment surface,

situated mostly eastward of the knobby terrain, has a similar

distribution of large impacts (> 1 km), but contains a significantly

greater number of smaller craters (< 1 km).

On its most basic level, this dimorphism suggests there is a distinct

geomorphic difference between the cratered and knobby terrains that

cannot be accounted for if exhumation by erosive forces has been the

primary factor in this area's morphological development. If one rules

out random impacts alone as a means of origin for this dimorphism (and

statistically there is no reason to attribute it to random cratering

because age determination for Martian surfaces have been based on

impact crater rates and densities (Carr, 1981, Tanaka, 1986), either

different geologic/erosional processes have been at work in these two

terrains or the two surfaces had origins in markedly different

morphologies or more likely a combination of both have occurred.

To verify the authenticity of this apparent cratering dimorphism,

crater counts (<1 km) were performed for the knobby and cratered

terrains with the following results: The average for the cratered

plain: 8800 craters/100,000 sq. km The average for the knobby terrain:

2000 craters/100,000 sq. km Ratio cratered/knobby: 4.4/1.

Even factoring in craters that appear to have suspect impact origin

(i.e. craters following distinct linear trends or fractures, crater

morphologies signifying possible origin from liquefaction(?) or

volcanic(?) processes, etc.) the following results have been obtained:

Cratered plain: 9700 craters/100,000 sq. km. Knobby terrain: 4900

craters/100,000 sq. km. Ratio: 2/1

Since this study is still preliminary in nature, definitive

conclusions as to the origin of this cratering ratio have not been

drawn at this time, but the cratering bimodal distribution appears to

cast doubt on claims that this area was subjected to a differential

erosion of at least 1 kilometer of soft, overlying sediment and that

the landform morphologies (knobs, hills, ridges, etc.) are primarily

the result of that process.

Using NASA's view one would have to accept that differential erosion

selectively eliminated nearly all evidence of small impacts on the

knobby terrain while leaving the cratered plain nearly untouched. A

more likely answer (from the evidence at Cydonia) is that landform

development was the result of a geologically interrelated set of

processes of both constructive and destructive nature which provided

the present character of the Cydonian surface.

Cydonia Landforms Remain Enigmatic

NASA's geological interpretation of Cydonia is even inadequate to

explain the definitive "natural features." Furthermore despite NASA's

approach, the particular Cydonian landforms in question have retained

their anomalous character.

The Face

The Face has been argued to be nothing more than an optical illusion

or a trick of shadows. Those arguments appear to be based more on

conjecture than on substantive geomorphic or geologic evidence. Since

the two images (Viking frames 35A72 and 70A13) containing the Face

were taken under a 17 degree difference in solar lighting angle, the

persistence of internal features in the Face precludes the latter

possibility. Thus the questions remaining are the authenticity of the

morphology of the Face and its possible origin.

After considerable review of the Face and other Cydonia landforms, the

conclusion can be drawn that the morphology of the Face is not a

result of an optical illusion. To the contrary, under the variation in

illumination angles between images 70A13 and 35A72, the features of

the Face change little, indicating that the origins of the "eyes,"

"mouth" and other features are likely the result of a variation in

surface morphology rather than shadows cast by as of yet indeterminate

protruding surfaces.

A comparison of the Face in frames 70A13 and 35A72 to some nearby

mesas also depicted in those frames corroborates the validity of the

Face's morphology. Using one mesa approximately 13 km due east of the

Face as an example, NASA's argument that the Face's morphology is an

illusion is further contradicted. This mesa has a steep-walled ridge

running lengthwise through its center and appears to contain a remnant

impact crater (1 km diameter) in its northern half. Because of the low

solar angle in 35A72 the shadows are heavy, obscuring some of the

central features on the eastern slope of the landform. In 70A13, the

greater solar angle allows for more of the shadowed eastern side in

35A72 to be discerned.

Though it is apparent that the two images of this mesa are slightly

different due to shadowing effects, the general trends within the mesa

are persistent. Not only does the definition of the sunward side of

the mesa appear to change little between images 35A72 and 70A13, the

definition of the ridge becomes more pronounced, revealing the

ruggedness of its eastern slope.

It is obvious that in viewing the images of this mesa, its general

morphology is authentic despite slight definition changes between the

images. Similar observations of the definition changes in the Face

between those images indicates that the same logic can be applied.

Thus to conclude that the morphology of the mesa is authentic (and it

is difficult to dispute that) after inspection of the images, it

follows that the morphology of the Face must be authentic as well. In

fact, there are less visual changes in the morphology of the Face

between images 35A72 and 70A13 than are noted in the mesa. Using

NASA's arguments of light and shadow or optical illusion, one might be

predisposed to conclude that the features of the mesa are more

suspicious than those of the Face.

An analysis of other landforms in this area supports the above

conclusions, but could the morphology of the Face be the result of a

random series of geologic events? Undoubtedly that is a possibility,

but the landform's obvious humanoid characteristics and societal

implications, in combination with other enigmatic landforms at

Cydonia, requires that a more thorough geologic evaluation of Cydonia

be pursued to acquire a resolution to this problem.

The "Cliff"

The "Cliff" is actually an elongate mesa 18 km NE of the Face,

apparently overlaying an ejecta blanket of a 3 km impact crater. The

Cliff contains a thin, almost linear central ridge running the length

of it. NASA has relied on the Cliff's relation to the nearby impact

crater in an attempt to explain its origins. Anonymous NASA evaluator

"Mr Q" (see The McDaniel Report, page 109) has stated the adjacent

crater to be a tuff ring or similar volcanic feature.

This statement is erroneous on even the most basic level. Cursory

observation of this crater immediately indicates its formation from

impact. The impact is surrounded by rampart-style ejecta ("Yuty-type")

and displays all of the features of a rampart crater, including

characteristic overlapping sheets of ejecta with lobate margins,

raised rims along the ejectamenta's outer edges and the extension of

ejecta about two crater diameters away from the impact. Though it has

been determined to date in this analysis of Cydonia that there is more

geomorphic evidence suggesting (at least isolated) volcanic activity

than recognized in previous studies, this crater is of unquestionable

impact origin.

Malin (see The McDaniel Report, pp. 109-110) indicates that the Cliff

is a product of stratigraphic superposition and differential erosion.

In this current study, the detailed analysis of the variety of

geomorphic features in Cydonia does not support a primary reliance on

differential erosion as a means of landform development. Evidence of

differential erosion is present in Cydonia, but not to the degree that

Malin suggests. Additionally, if the Cliff is a relic mesa derived

from an extensive preexisting surface, there is no supporting evidence

for that, either in the crater or on its ejectamenta.

Also, no evidence has been found for the remnants of this preexisting

surface in association with any of the other ejecta blankets of

significant impact craters (> 1 km) in this area. To date, the "Cliff"

appears to be an isolated event. Another argument might be that only

this impact had any of the preexisting surface deposited on it, but

without sediment deposition in the impact crater itself. Is such a

restrictive solution geologically plausible or provable? And what

questions would that pose for the feasibility of the depositional


A third possibility is that the "Cliff" existed before the impact, but

there is no evidence of the ejecta having overlain the Cliff, though

the ejecta flow extends beyond the Cliff for at least a kilometer.

There is also no evidence to imply that the Cliff is associated with

the impact event itself. If the Cliff predated the impact, it would

seem logical for some of the impact's ejecta to have overlain the

Cliff or at least to have flowed around the base of the Cliff as is

known to have occurred in other landforms/impact associations in

Cydonia, but there is no evidence for that either.

Since ejecta appears to resist erosion as shown by the numerous

pedestal craters on Mars, if ejecta had been thrown on the Cliff,

trace evidence of that event might be expected to be found. Again,

nothing. Because of the general lack of evidence for any definitive

explanation for the Cliff's origin and its timing in relation to that

of the adjacent impact, the Cliff and associated cratering event

remains enigmatic.

Other evidence that undermines the Cliff's origin as a differential

erosion product are the trends within the various groupings of small

pedestal craters (< 1 km) that dot the cratered plain. These groupings

suggest that this area was not buried with soft sediment to the degree

that Malin claims. The alignments and groupings of pedestal craters

moreover provides evidence of a preexisting topographical surface that

was much thinner than that suggested by Malin.

The Tholus

The Tholus at Cydonia (name not to be confused with other "Tholus"

names designating volcanic vents on Mars) is an isolated,

semi-circular, mound-like landform that lies in the cratered plain

(J-12). The mound ("tholus" means "mound") is of relatively low relief

in relation to the knobby terrain to the west. It appears to contain a

thin depression or groove that circles the landform at its base and

spirals up toward the landform's peak in a clockwise fashion cutting

through the mound.

Another similar mound, Tholus-A, lies approximately 20 km to the south

of the Tholus and is about one-third the size of the Tholus. It too

contains a groove that spirals from its base to the peak, but the

spiral is counterclockwise. The smooth gradation in elevation present

in the Tholus is less evident in Tholus-A. The spiral almost appears

to be the result of a low escarpment which winds up the feature.

A third elliptical hill lying about 8 km of the Tholus sits on the

edge of what appears to be a meandering scarp line that runs

southwest/northeast. Though the general shape is similar to the Tholus

and Tholus-A, this landform has a steeper gradient. A fourth

low-relief mound (F,G-14) is located about 25 kilometers southeast of

the Tholus in a line with the above mentioned landform. This mound

appears to be eroded remnants of a larger landform and does not

exhibit any of the symmetry of the Tholus.

These features are surrounded by a number of small impact craters in

various stages of degradation. Some are fresh, others eroded into

pedestal craters and others eroded to remnants of their original form.

The Tholus, and to a lesser degree Tholus-A, stand in stark contrast

to the surrounding landforms. They display no evidence of volcanism,

are not impact-related and are difficult to explain as remnants of

larger non-distinct landforms because of their symmetrical shapes and

uniform, low gradients. Their lack of ruggedness or mesa-like

appearance makes both landforms enigmatic and problematic to other

landforms in this area.


The above-discussed Cydonia landforms are but a few of the problematic

landforms in this area. To lessen their possible significance by

explaining them as erosional remnants of a preexisting surface,

without supporting evidence, is clearly not a rigorous scientific

approach. To the contrary, what exactly is needed are "more rigorous

geologic evaluations" to determine the origins of these controversial


This review has pointed out inconsistencies in previous geologic

arguments and indicates, at the very least, that geologic

generalizations are not an acceptable method to explain surface

features in Cydonia, enigmatic or not. Such "ballpark" solutions add

little to the resolution of the landforms under study. The Cydonia

landforms may ultimately turn out to be no more than an odd assortment

of enigmatic natural features, formed by random geologic processes,

but they may as well turn out to have significant implications for

humanity. An unbiased approach assumes neither, but strives for the



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