This visualization presents a 2D heatmap of the Old Faithful Dataset, using Vega-Lite’s binned rectangle marks to show the distribution of eruptions across four repeated dimensions (rows and columns labeled "1" and "2"). It layers two heatmap specs—one for overall counts and one filtered by a user-driven interval brush—with an outlier field controlling conditional coloring. The code uses vegaEmbed, vega-lite, and d3.csv to load data from a remote CSV, configures a green heatmap color scheme, and places the legend offset left.