RECOMMENDED LESSONS: Runoff Runoff is precipitation that did not get (infiltrated) absorbed into the soil, or did not evaporate, and therefore made its way from the ground surface into places that water collect. Runoff causes erosion, and also carry chemicals and substances on the ground surface along to the rivers where the water ends up.
Noun. 1. obelisk-a stone pillar having a rectangular cross section tapering towards a pyramidal top. pillar, column-a vertical cylindrical structure standing alone and not supporting anything (such as a monument).
The tapered shaft, or obelisk, is made of stone and is covered with white marble. The monument stands just over 555 feet. Memorial stones from the 50 States, foreign countries and organizations line the inside walls. The top of the monument, which you can get to only by elevator, provides a panoramic view of the city.