Scientific Argument - What Created a Channel on Mars

 For my science class, we are wrapping up our first unit (geology on Mars), and were given the task to write a scientific argument "letter" about a specific channel on Mars based on all of the information we learned during the unit.

Dear Universal Space Agency, 

I have figured out what formed the mystery channel on Mars. The evidence we discovered supports the claim that flowing water created the channel. Below is my evidence & reasoning to support the flowing water claim.

My first piece of evidence are the satellite images of channels formed on Earth by flowing water. The images of the Earth channels show curves and branches, similar to how the mystery channel on Mars looks. As both Mars & Earth are similar rocky planets, having a similar shaped channel could mean that they were created by the same geologic process (in this case, water).

My second piece of evidence is the flowing water model lab, and how the water channel held its shape even after water stopped flowing down the stream. Since the model showed that flowing water holds a channel shape even after water stopped flowing, it is an indicator that the Mars channel could have been formed by water, and held its shape afterwards, just like the model. 

Another piece of evidence I have gathered is an image of the type of rock at the end of the channel. The image shows that there is sediment pebbles & rock, a type of rock only seen near water channels on Earth. If sediment is only found near water on Earth, it has to be the same on Mars, as both are similar rocky planets. Also, if the channel were created by lava (another possible option), the rock would not be sediment, it would be dark, cooled lava (which it is not). 

My final piece of evidence is the flowing lava model, specifically how the channel ended up looking in comparison to the channel on Mars. The lava model created a channel that was straight and had no branching, completely different than the channel on Mars in terms of shape & looks. Though it is possible for channels to look different, both should have similar shape & features, which they do not (this eliminates that the channel could have been created by lava).

Based on all of the evidence gathered, it is clear that flowing water formed that channel on the surface of Mars.