```r
library(ggplot2)
g1 = ggplot() + geom_sf(data = nz, aes(fill = Median_income)) +
  geom_sf(data = nz_height) +
  scale_x_continuous(breaks = c(170, 175))
g1
```

<div class="figure" style="text-align: center">
<img src="figures/nz-gg-1.png" alt="Map of New Zealand created with ggplot2." width="576" />
<p class="caption">(\#fig:nz-gg)Map of New Zealand created with ggplot2.</p>
</div>