Results and Discussion of the Broad Cove Baseline Data 2006

Entering into this project, I and my peers had no clue as to what to expect.  Nobody had used this technology to make a profile of an intertidal zone before, and so the problems and the results that could be expected were, shall we say, “known unknowns.”  This is a generic breakdown of the results of this unique form of intertidal profiling.  First, the generic discussion of what each profile means. 

Elevation Profiles for Broad Cove

This is a histogram of the north profile of Broad Cove.

It begins on a fairly steep slope, and then begins to shallow out around the intertidal area.  This seems to be fairly logical, since the tide would deposit particles in large sizes and amounts during storms, and then steadily erode them away during the rest of the time due to the constant wave action.

This is a graph of the southern profile of Broad Cove.  It follows the same general pattern as can be seen in the northern profile.  It starts at a high slope, and then shallows out around the area of mean high tide.  There are, however, a few differences between the two that will be discussed in more detail later.

This cross-section follows a vastly different pattern from the longitudinal profiles.  It begins on the left, which is the northern side, and ends with a sharp, jagged gradient on the south side.   The middle is characterized by an extremely flat gradient.  This is most easily explained by the fact that this is the eastern edge of the cove, and this particular transect was taken entirely under the high tide mark.  Therefore, in relation to the other two graphs, it shows the comparatively    shallow slope  caused by the constant motion of the tides.

And this is the graph representing the western cross-section.  Since this was further away from the shore, it will display the slope differences that we noted earlier between the north and south profiles.  Therefore, the upward grade going from the north to the south profile is quite reasonable, discounting the steep bedrock on either side.

So, the general shape of the cove floor is beginning to come into shape.  The cove begins on a fairly shallow slope, and then, at the high tide mark, begins to shift toward a generally steeper slope.  This slope is steeper on one side than on another, however, and will therefore lead to a sort of “tilted” upper layer.  The relationship between the north and south profiles can more easily be seen by looking at this figure.

The south profile follows a much steeper path than the northern profile does.  The south starts at a higher point, and ends at very nearly the same height.  This means that somehow, the south is being affected by the ocean differently than the north.  Maybe some more information will prove helpful in determining exactly what kind of difference.

The following information is graphs detailing the summary for the pebble counts in each of the previously defined areas.  This information could prove useful in determining the type of forces that molded the general shape of the cove bed, because those same forces will affect the types of particles that will be found in the different levels.

First, I’ll make a comparison between the two latitudinal profiles, since they are the simplest and the easiest to explain.  The eastern cross section was taken along the high tide line, so all of the larger particles that were deposited by the constant motion of the tides will be found along the line.  But since it is along the high tide line, it is fairly uniform due to the constant action of the tides.  The west, however, experiences an extremely sharp division in particle size between the north and the south ends of the profile.  The north is characterized by a much larger number of much smaller particles.  This means that the southern end of the profile has much larger particles along this cross section.

But does this characterization hold true for the entire northern and southern profiles?  Looking at our data, we were able to see that it does.  The southern profile, in general, has a much larger number of large particles, large particles being 64 mm and above.  The north has almost its entire stock of particles focused below the 64 mm mark, while the south has almost no particles smaller than 64 mm. 

But, what does this all mean?  In this section, I will discuss the results of this particular experiment, and some of my surmises as to why it happened, along with thoughts about possible uses for this information.

Discussion of the Results

First, to recap the general profile of Broad Cove.  In general, it starts at a steep slope, and then shallows out around the high tide mark.  The south side has a much steeper slope than the north, and has, in general, a larger particle size.  In physics, there is a simple law that characterizes the relationship between an object’s size and the power needed to move it.  It is F=ma, or Force is equal to Mass times Acceleration.  In our situation, we want to know how much force it takes to move a larger particle the same distance as a smaller one.  Therefore, acceleration is constant.  So, our new relationship looks like this: a=F/m.  So, as the mass of the object goes up, the force must increase to keep the acceleration at a constant value.  Basically, the bigger an object is the more force it will take to move it.  This may seem like a basic law, but it requires proving, for it is central in the discussion ahead.  

As we saw previously, the south side of the cove had more large particles.  As we proved in the previous paragraph, larger particles take more force to move them.  So, the reason there are less particles of a large side along the north, given the previous information, is that there is less force on the north side than on the south.  And, as was also stated previously, the only affect that can be made on the area above the tide zone must be done by a storm.  So, storms are putting more force on the south side than on the north side.  The possible reasons for this are widely varied, including the shape of the cove, the prevailing winds, land versus ocean, shape of the island, etc.  But, a few of these factors can be excluded.  For example, this particular cove faces east.  The layout of Appledore island is in such a way that the only land to the east of Broad Cove is Lisbon, Portugal.  Therefore, the island is not interfering in wave force, and neither is the mainland.  That leaves the shape of the cove, and prevailing winds for the factors listed.  As there are no pictures of the cove, the only information I can offer is a reassurance that the cove is not fashioned asymmetrically, so the ocean is free to affect either side equally.  Therefore, the only conclusion that I can come to at this time is that the prevailing winds are blowing toward the southwestern edge of the cove, and therefore are depositing the larger particles there.  This would also cause many small particles to be deposited, forming a base substrate that is higher in elevation than the rest of the cove.  So, all of our evidence is consistent with the idea that the winds are prevailing from the northeast.

But, as the Lutheran that I am, I must ask the question “what does this mean”?  What possible purpose could this type of profile serve?  Who will it benefit?  How will it advance humanity?    This, in my opinion, can serve several functions, both in the short and in the long term.

This is one possibility:  if a group was determining where to place a long-term testing site, such as some sort of station or expensive testing equipment, they would want to place it in as sheltered of a place as possible.  That would mean, in this case, placing it in the northwest corner of the cove. 

Another, possibly more applicable, option would involve many tests taken over a period of years.  If a new sample were taken every month, or even every year, over a period of time, an interested scientist could have hard data on the changing effects of the environment on a particular area.  So, if larger particles are being pushed higher up Broad Cove every year, that would indicate that storm forces are increasing in the area.  Or, if the particles are being shifted to the north or south end of the cove, or becoming evenly distributed, that would mean that the prevailing winds of the area are shifting.  This particular method of sampling, taken over a long-term period, could have huge effects for watching the changes in the environment.

With every new invention, a trial period must follow before acceptance, and therefore use, occurs.  Something must be used many times and seen in action often in order to understand the full uses for it.  Steam was converted to rotary power in the first century as a toy, but it took until 1690 for people to see that it might have a use beyond entertainment.  At the moment, this method seems to have many possibilities, but who knows what the future might bring?  Who can possibly claim to know what some future ecologist, or biologist, or physicist, or chemist, or artist, or engineer, or historian, or archaeologist, etc. might find for this?  All I can say right now is this:  laser level profiling is going somewhere.  And we were the ones that started it.

Noah Johnson

last updated 9 August 2006

More Information

• Baseline M&M 2006
• Baseline Results 2006