Google Earth is a fun tool for exploring places to go hiking or riding – or for general aerial exploration. Recently, I was looking for hiking places accessible by a short bike ride from my house, and noticed something curious about the nearby Phoenix Mountain Preserve:
Notice the two distinct colors of the ground along the small drainage between the mountain peaks. The ground nearest to the small arroyo is grayish, while the ground further from the drainage is orange. This could be due to many reasons:
1) The different colors represent different bedrock types comprising the ground surface. The mountains are various types of metamorphic rocks that exhibit different colors. This is apparent in the imagery near the mountain peaks, with the color bands having a general southwest to northeast trend.
2) The colors could represent different age surfaces, as older surfaces may exhibit a different patina due to weathering or pedogenic processes.
3) Assuming the ground is sediment, the colors could represent different depositional processes, with alluvium exhibiting a different color than colluvium.
4) Again assuming sediment, the colors could be due to different rock types that comprise the sediment.
Or, it could be a combination of the above. Hopefully, as the weather is nice over the next few weeks I will get some time to check things out, and post back with an answer.