Article: The development of writing is counted among the many achievements and innovations of pre-Columbian American cultures. Independent from the development of writing in other areas of the world, the Mesoamerican region produced several indigenous writing systems beginning in the 1st millennium BCE. What may be the earliest-known example in the Americas of an extensive text thought to be writing is by the Cascajal Block. The Olmec hieroglyphs tablet has been indirectly dated from ceramic shards found in the same context to approximately 900 BCE, around the time that Olmec occupation of San Lorenzo Tenochtitlán began to wane.

Now answer this question: What is presumed to be written upon the Cascajal Block?
extensive text